Article

Heart Rate Variability Biofeedback Decreases Blood Pressure in Prehypertensive Subjects by Improving Autonomic Function and Baroreflex

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Abstract

Individuals with prehypertension are at risk of hypertension and cardiovascular diseases, and yet efficient interventions are lagging behind. Studies indicate that heart rate variability-biofeedback (HRV-BF) increases HRV and baroreflex sensitivity (BRS) as well as reduces related pathological symptoms, suggesting potentially beneficial effects of HRV-BF on prehypertension, but little is known about these effects. In this study, these effects were investigated and their mechanisms were explored. The effect of HRV-BF on prehypertension in young adults and its potential mechanism were explored. Forty-three (43) individuals with prehypertension were recruited and classified into three categories: HRV-BF group, slow abdominal breathing group, and control group. All groups were assessed with measurements of noninvasive blood pressure (BP), BRS, respiration, and galvanic skin response (GSR) at pre-intervention, in the entire process of each session, at postintervention, as well as at a 3-month follow-up. Interventions: Subjects participated in a 10-session HRV-BF protocol or simple slow abdominal breathing protocol conducted over 5 weeks. A 3-month follow-up was also performed on these individuals. The incidence of prehypertension was as high as 14.5% in young college students. Individuals with prehypertension were lower in BRS (7.5±5.2 ms/mm Hg) and HRV (log10-transformed of the standard deviation of normal-to-normal beats [SDNN]=1.62±0.13 ms, lgTotal power of spectral density in the range of frequencies between 0 and 0.4Hz (TP)=8.02±0.55 ms2) than those with normal blood pressure (BRS=18.4±7.4 ms/mm Hg, lgSDNN=1.79±0.10 ms, lgTP=8.68±0.85 ms2). HRV-BF reduced blood pressure (from 131.7±8.7/79.3±4.7 mm Hg to 118.9±7.3 mm Hg/71.9±4.9 mm Hg, p<0.01), increased BRS (from 7.0±5.9 ms/mm Hg to 15.8±5.3 ms/mm Hg, p<0.01) and increased HRV (lgSDNN from 1.61±0.11 to 1.75±0.05 ms, and lgTP from 8.07±0.54 to 9.08±0.41 ms2, p<0.01). These effects were more obvious than those of the slow-breathing group, and remained for at least 3 months. HRV-BF also significantly increased vagus-associated HRV indices and decreased GSR (indices of sympathetic tone). These effects suggest that HRV-BF, a novel behavioral neurocardiac intervention, could enhance BRS, improve the cardiac autonomic tone, and facilitate BP adjustment for individuals with prehypertension.

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... La RSA es la variación de la frecuencia cardiaca que acompaña a la respiración, es decir, las oscilaciones correspondientes a la frecuencia cardiaca que pueden interpretarse como influencias de la respiración en el nodo sinoauricular del corazón 10,12 . La frecuencia cardiaca aumenta durante la inhalación, cuando el aire dentro de los pulmones es rico en oxígeno; disminuye durante la exhalación, cuando aumenta la concentración de dióxido de carbono dentro de los pulmones 10,14 . La inhalación suprime temporalmente la actividad vagal, causando una disminución en el intervalo entre latidos y un aumento en la FC; la exhalación activa la actividad vagal, causando un aumento en el intervalo entre latidos y una disminución de la FC 10,15 . ...
... Es una oscilación natural entre el ciclo de respiración y la FC. Esto maximiza el RSA y aumenta notablemente la VFC 10,14 . Exhalaciones más prolongadas y respiraciones más lentas pueden aumentar la amplitud de la RSA debido a amplitudes de mayor tamaño alcanzables. ...
... Los resultados sobre la VFC en los sujetos prehipertensivos mostraron LH y HF inferiores a las de los sujetos normotensos. Estas diferencias indicaron que tanto la sensibilidad barorrefleja como la VFC presentaban una alteración en sujetos prehipertensos 14 . El estudio de Chen también encontró diferencias en sus hallazgos entre los sujetos normotensos y prehipertensivos. ...
Article
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El biofeedback de la variabilidad de la frecuencia cardiaca (VFC-BF) consiste en una variedad de retroalimentación cuyo objetivo es el restablecimiento del equilibrio del sistema nervioso autónomo (SNA) a través del control respiratorio en aquellos sujetos que padez-can disfunción autonómica. El objetivo principal de esta revisión fue analizar la evidencia científica disponible recientemente sobre la VFC-BF, así como explicar sus mecanismos de acción involucrados. Se llevó a cabo una revisión bibliográfica de tipo narrativo. Se utiliza-ron revisiones sistemáticas preferentemente para contrastar evidencia sobre su mecanismo de acción. A partir de ahí se examinaron ensayos clínicos controlados aleatorizados para evaluar y comparar resultados recientes sobre VFC-BF. Tras este análisis, comprobamos que el mecanismo de acción de dicho abordaje terapéutico no resulta aún concluyente, ya que los distintos estudios discrepan en la interpretación de los parámetros de la variabilidad de la frecuencia cardiaca (VFC). Por su parte, las revisiones sistemáticas consultadas coinciden en que la aplicación de la VFC-BF provoca una mejora de la disfunción autonómica a través del reforzamiento del sistema barorreflejo. Sin embargo, los efectos específicos que tiene este procedimiento sobre el SNA parasimpático aún no están claros. Por otro lado, la distinta
... Gross et al. 17 also performed a test-retest as regards the RF, but they found an RF stability consisting of a range of 0.5 similar to the RFE variable. Finally, Hallman et al. 33 , following a similar approach as Lin et al. 18 , checked the RF for each session in a posteriori analysis and found stability between ten sessions. Therefore, our results confirmed the previous outcomes reported by Lin et al. 18 . ...
... Finally, Hallman et al. 33 , following a similar approach as Lin et al. 18 , checked the RF for each session in a posteriori analysis and found stability between ten sessions. Therefore, our results confirmed the previous outcomes reported by Lin et al. 18 . On pooling participants, the RF was around 6 b/m (0.1 Hz), which is the most common rate. ...
... Previous studies have shown that HRVB, assessing the individual RF only at the beginning of the intervention, enhanced HRV time domain parameters compared to controls 42 and to baseline 35,36,43 . Lin et al. 18 , who also found RF changes over time, found that HRVB increased HRV parameters and baroreflex sensitivity, as well as reduced BP in pre-hypertension participants. On the other hand, there are also studies that find no significant differences or partial benefits of HRVB 6,37,44 . ...
Article
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Heart Rate Variability Biofeedback (HRVB) is based on breathing at an optimal rate (or resonance frequency, RF) corresponding to the respiratory sinus arrhythmia (RSA). Our aim is to check whether the RF is a stable factor and analyse the HRV parameters individually per each breathing rate, comparing it with free slow breathing. A sample of 21 participants were trained in a test–retest HRVB protocol. The results indicated that RF changed between Test and Retest sessions in 66.7% of participants. This instability could be related to the average of interbeat interval (IBI). HRV time domain parameters (SDNN and RMSSD) were significantly higher for RF than for other breathing rates, including 6 breath/min and free slow breathing. Free slow breathing showed a lower heart rate averages than RF and other slow breathing rates. Overall, our study suggests the relevance of assessing RF individually and before each HRVB session, because the maximum cardiovascular benefits in terms of increasing HRV were found only at RF. Thus, breathing at the individualized and momentary frequency of resonance increases cardiac variability.
... A small HRV-biofeedback (HRV-BF) device called "Qiu" (Biosign GmbH, Ottenhofen, Germany) can indicate HRV by showing a green or red light, depending on the variability. By learning relaxed breathing of about 5-7 breaths per minute 14 including a feedback of the measured HRV parameters, it is possible to influence the HRV and inner tensions; blood pressure can be reduced 15,16 and asthma symptoms can be improved, 17,18 thus stress and pain can be alleviated. [19][20][21] An important step of therapy is to understand the patient's perception of symptoms. ...
... (M-EK05: 8) "And then the legs were especially quite painful and it actually went right into the feet." (B-RD07: 15) Limitations in daily life "When it starts, the pain builds up and it cramps more and more, and the point can come where the pain is so strong that I cannot move anymore, my cycle collapses, I feel like vomiting, I sweat, I'm cold, I shake and I can't speak." (K-ML14: 2) "(My girlfriend) (…) could not come to me, because that would not have brought anything. ...
... Through the convulsions in the abdomen they described an inward contracting, thus a narrower body silhouette, but at the same time also the feeling of a pain that pushed outwards. A widened body silhouette has also been described, often linked to a feeling of puffiness (ML14: [15][16][17][18][19]; (M-FP06:10). Body drawings helped in perceiving and describing the changed body schema: The ability to recognize the body's limitations was reported as a changing aspect (Figs. ...
Article
Objective: The purpose was to involve women's personal experiences of daily life with primary dysmenorrhea (PD) and their body perceptions of the dysmenorrhea-related symptoms in relation to the treatment procedure and to explore the perception of Heart Rate Variability Biofeedback (HRV-BF) or Rhythmical Massage (RM) according to Ita Wegman as a therapeutic intervention within the framework of Anthroposophic Medicine (AM). Design: From 60 women who participated in our randomized controlled trial analyzing the effects of HRV-BF or RM, we examined 14 women to get an in-depth understanding of this prevalent disease, using a qualitative design. The women drew their body image before and after the 3-month-intervention on body silhouette diagrams and described their body-perceptions. Semi-structured interviews were conducted and analyzed using content analysis. Results: Women perceive dysmenorrhea as a disturbance of their daily lives. The body images showed the variations of experience, from misbalances of body perception to overwhelming attacks of pain hindering a normal life for several days per month. Perception of therapeutic interventions range from relaxing without effects on complaints to important changes and benefits on the physical, emotional, and/or social level. Both therapies can support stronger self-awareness through enabling a more differentiated sense of body-awareness, sometimes resulting in women experiencing fewer limitations in their daily lives. Effects may be influenced by the readiness to resonate with the therapeutic process. Qualitative interviews and body images can serve as tools to integrate individuality and help to integrate embodied more or less conscious aspects of complaints. Conclusions: The body silhouette diagram could be used systematically to include reflections of embodiment in the therapeutic and research settings and help to diagnose in advance the ability of participants to resonate with interventions. RM and HRV-BF influence self-awareness and may enable salutogenic and self-management capacities. For more effective treatment it may be helpful to make treatment suggestions based on an integrative individual history that includes preferences, expectations and a body silhouette diagram.
... La RSA es la variación de la frecuencia cardiaca que acompaña a la respiración, es decir, las oscilaciones correspondientes a la frecuencia cardiaca que pueden interpretarse como influencias de la respiración en el nodo sinoauricular del corazón 10,12 . La frecuencia cardiaca aumenta durante la inhalación, cuando el aire dentro de los pulmones es rico en oxígeno; disminuye durante la exhalación, cuando aumenta la concentración de dióxido de carbono dentro de los pulmones 10,14 . La inhalación suprime temporalmente la actividad vagal, causando una disminución en el intervalo entre latidos y un aumento en la FC; la exhalación activa la actividad vagal, causando un aumento en el intervalo entre latidos y una disminución de la FC 10,15 . ...
... Es una oscilación natural entre el ciclo de respiración y la FC. Esto maximiza el RSA y aumenta notablemente la VFC 10,14 . Exhalaciones más prolongadas y respiraciones más lentas pueden aumentar la amplitud de la RSA debido a amplitudes de mayor tamaño alcanzables. ...
... Los resultados sobre la VFC en los sujetos prehipertensivos mostraron LH y HF inferiores a las de los sujetos normotensos. Estas diferencias indicaron que tanto la sensibilidad barorrefleja como la VFC presentaban una alteración en sujetos prehipertensos 14 . El estudio de Chen también encontró diferencias en sus hallazgos entre los sujetos normotensos y prehipertensivos. ...
Article
Full-text available
El biofeedback de la variabilidad de la frecuencia cardiaca (VFC-BF) consiste en una variedad de retroalimentación cuyo objetivo es el restablecimiento del equilibrio del sistema nervioso autónomo (SNA) a través del control respiratorio en aquellos sujetos que padez-can disfunción autonómica. El objetivo principal de esta revisión fue analizar la evidencia científica disponible recientemente sobre la VFC-BF, así como explicar sus mecanismos de acción involucrados. Se llevó a cabo una revisión bibliográfica de tipo narrativo. Se utiliza-ron revisiones sistemáticas preferentemente para contrastar evidencia sobre su mecanismo de acción. A partir de ahí se examinaron ensayos clínicos controlados aleatorizados para evaluar y comparar resultados recientes sobre VFC-BF. Tras este análisis, comprobamos que el mecanismo de acción de dicho abordaje terapéutico no resulta aún concluyente, ya que los distintos estudios discrepan en la interpretación de los parámetros de la variabilidad de la frecuencia cardiaca (VFC). Por su parte, las revisiones sistemáticas consultadas coinciden en que la aplicación de la VFC-BF provoca una mejora de la disfunción autonómica a través del reforzamiento del sistema barorreflejo. Sin embargo, los efectos específicos que tiene este procedimiento sobre el SNA parasimpático aún no están claros. Por otro lado, la distinta
... Breathing at RF maximizes HR oscillations by creating a 0 degree phase shift between HR and respiration, while BP response from HR exhibit a 180 degree phase shift occurring at approximately 5-s delay as a result of mechanical response (Vaschillo, Vaschillo, & Lehrer, 2006). Similar to slow breathing at a set pace, RF breathing has emerged as a promising tool to enhance performance, reduce stress and anxiety (Jester, Rozek, & McKelley, 2019;Lehrer & Gevirtz, 2014) and positively influence clinical symptoms in a number of disorders including depression (Lin et al., 2019), asthma (Taghizadeh, Eslaminejad, & Raoufy, 2019), and prehypertension (Lin et al., 2012). ...
... This raises the question as to whether precise measurement of the RF is essential for the reported beneficial clinical effects of individualized RF or a standardized paced breathing at 5-7 breaths per min is all that is required. Lin et al. (Lin et al., 2012) investigated the effects or either paced breathing at RF compared to slow breathing (6 breaths/min) in individuals with prehypertension and found that both schemes of breathing resulted in a decrease in BP over a period of 5 weeks and that the decrease in BP was more marked in those breathing at RF except for the first session where the BP fall was identical with either RF or RF + 1. They also found that RF induced stronger changes in HRV indices and in the baroreflex function compared with slow breathing which may explain better hemodynamic changes. ...
Article
Full-text available
Abstract Acute slow breathing may have beneficial effects on cardiovascular regulation by affecting hemodynamics and the autonomic nervous system. Whether breathing at the resonance frequency (RF), a breathing rate that maximizes heart rate oscillations, induces differential effects to that of slow breathing is unknown. We compared the acute effects of breathing at either RF and RF + 1 breaths per minute on muscle sympathetic nervous activity (MSNA) and baroreflex function. Ten healthy men underwent MSNA, blood pressure (BP), and heart rate (HR) recordings while breathing for 10 min at their spontaneous breathing (SB) rate followed by 10 min at both RF and RF + 1 randomly assigned and separated by a 10‐min recovery. Breathing at either RF or RF + 1 induced similar changes in HR and HR variability, with increased low frequency and decreased high frequency oscillations (p
... The effects of HRV-BF were found to decrease stress and anxiety in healthy populations (Lee et al. 2015;Sarwari and Wahab 2018) and high-stress students (Aritzeta et al. 2017;Larson et al. 2010;Ratanasiripong et al. 2015;Vitasari et al. 2011). HRV also decreased breathing rates and increased cardiac autonomic activations after five to 11 sessions for patients with physical illnesses, such as asthma (Lehrer et al. 2004), hypertension/prehypertension (Lin et al. 2012;Wang et al. 2010), coronary artery disease (Cowan et al. 2001;Del Pozo et al. 2004;Lin et al. 2015a, b;Nolan et al. 2005;Swanson et al. 2009), and irritable bowel syndrome (Stern et al. 2014). Some studies also applied HRV-BF to patients with mental disorders, such as anxiety disorders (Tabachnick 2015), and major depressive disorders (Karavidas et al. 2007). ...
Article
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Heart rate variability biofeedback (HRV-BF) has been confirmed to increase heart rate variability (HRV) and cardiac outflows by baroreflex in healthy populations and clinical patients. Autogenic training (AT) is common used in the psychological intervention. This study integrates a single-session of HRV-BF and AT into a high-technology mobile application (app), and examines the effects on HRV indices, breathing rates, and subjective relaxation scores. Healthy college students were recruited and assigned to the single-session HRV-BF group or AT group. Participants in the HRV-BF group received HRV-BF combined with paced breathing training, which gradually stepped down their breathing rates from 12, to 8, to 6 breaths/per min; and received feedback of HRV indices from the app. Participants in the AT group received autogenic training and feedback of heart rate from the app. A chest belt Zephyr BioHarness was connected through Bluetooth to a Zenfone5 mobile phone, it collected the signals of interbeat intervals and breathing rates at pre-training, mid-training, and post-training stages. The Kubios HRV software was used to analyze HRV indices. The results reveal higher HRV indices and lower breathing rates during mid-training and post-training in the HRV-BF group compared to the AT group. There were higher high-frequency of HRV at post-training than pre-training in the AT group. Participants of both groups increased their subjective relaxation scores after training. The HRV-BF protocol increased cardiac outflows by baroreflex and decreased breathing rates, and the AT protocol increased high-frequency of HRV. These high-technology wearable devices combined with psychological interventions will apply to various populations in the future.
... The ANB and RNB showed a temporary withdrawal of parasympathetic activity and a concomitant increase in HR that can be linked to higher baroreflex sensitivity and oxygen saturation (Mason et al., 2013). Further, slow breathing studies have demonstrated beneficial effects on cardiorespiratory functions in patients with cardiac surgery, prehypertension, asthma, and major depressive disorder (Karavidas et al., 2007;Lin et al., 2012). The findings of the present study are consistent with the previous study (Lin et al., 2014) which implies that slow yoga breathing practices may be beneficial for the physical and mental health of clinically healthy individuals, mainly due to improvements in the subjective feeling of relaxation. ...
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This study investigated the immediate effect of slow yoga breathing (SYB) at 6 breaths per minute (bpm) simultaneously on working memory performance and heart rate variability (HRV) in yoga practitioners. A total of 40 healthy male volunteers performed a working memory task, ‘n-back’, consisting of three levels of difficulty, 0-back, 1-back, and 2-back, separately, before and after three SYB sessions on different days. The SYB sessions included alternate nostril breathing (ANB), right nostril breathing (RNB), and breath awareness (BAW). Repeated measures analysis of variance showed a significant reduction in reaction time (ms) in 2-back condition immediately after ANB (−8%), RNB (−8%) and BAW (−5%) practices. Similarly, the accuracy was improved in the 0-back condition after RNB (4%), and in the 2-back condition after ANB (6%) and RNB (6%) practices. These results suggest that SYB practice enhances cognitive abilities (8–9%) related to memory load and improves the functioning of cardiac autonomic activity, which is required for the successful completion of mental tasks.Trial registered in the Clinical Trials Registry of India (CTRI/2018/01/011132).
... The HRV signal is a noninvasive marker of the performance of autonomic nervous and cardiovascular systems. It has been shown that the BP is correlated with the time-domain and frequency-domain properties of HRV [30][31] [32]. HRV can be used to estimate the stress level of a person [33]. ...
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In this paper, we present a machine learning model to estimate the blood pressure (BP) of a person using only his photoplethysmogram (PPG) signal. We propose algorithms to better detect some critical points of the PPG signal, such as systolic and diastolic peaks, dicrotic notch and inflection point. These algorithms are applicable to different PPG signal morphologies and improve the precision of feature extraction. We show that the logarithm of dicrotic notch reflection index, the ratio of low-to high-frequency components of heart rate (HR) variability signal, and the product of HR multiplied by the modified Normalized Pulse Volume (mNPV) are the key features in accurately estimating the BP using PPG signal. Our proposed method has achieved higher accuracies in estimating BP compared to the previously reported methods that only use PPG signal. For the systolic BP, the achieved correlation coefficient between the estimated values and the real values is 0.78, the mean absolute error of the estimated values is 8.22 mmHg, and their standard deviation is 10.38 mmHg. For the diastolic BP, the achieved correlation coefficient between the estimated and the real values is 0.72, the mean absolute error of the estimated values is 4.17 mmHg, and their standard deviation is 4.22 mmHg. The achieved results fall within Grade A for diastolic, Grade C for systolic and Grade B for mean BP based on BHS standard.
... The mechanisms responsible for the BP lowering induced by biofeedback when it occurs are incompletely described. There is some evidence that biofeedback alters the autonomic nervous system balance and increases baroreceptor sensitivity (105,108,110,111). ...
Article
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Background: African Americans have disproportionately high rates of cardiovascular disease (CVD). Left ventricular hypertrophy (LVH) is an independent risk factor for CVD and may contribute to this disparity. Psychological stress contributes to LVH in African Americans and other populations. Objective: This study evaluated the effects of stress reduction with the Transcendental Meditation (TM) technique on preventing LVH in African American adults with hypertension. Setting: Martin Luther King Hospital - Charles R. Drew University of Medicine and Science, Los Angeles, CA. Method: In this trial, 85 African American adults (average 52.8 years) were randomly assigned to either TM program or health education (HE) control group and completed posttesting. Participants were tested at baseline and after six months for left ventricular mass index (LVMI) by M-mode echocardiography, blood pressure, psychosocial stress and behavioral factors. Change in outcomes was analyzed between groups by ANCOVA and within groups by paired t-test. Results: The TM group had significantly lower LVMI compared with the HE group (-7.55gm/m2, 95% CI -14.78 to -.34 gm/m2, P=.040). Both interventions showed significant within group reductions in BP, (SBP/DBP changes for TM: -5/ -3 mm Hg, and for HE: -7/-6 mm Hg, P=.028 to <.001) although between group changes were not significant. In addition, both groups showed significant reductions in anger (P=.002 to .001). There were no other changes in lifestyle factors. Conclusions: These findings indicate that stress reduction with TM was effective in preventing LVMI progression and thus may prevent LVH and associated CVD in high-risk African American patients.
... The mechanisms responsible for the BP lowering induced by biofeedback when it occurs are incompletely described. There is some evidence that biofeedback alters the autonomic nervous system balance and increases baroreceptor sensitivity (105,108,110,111). ...
Article
The multifactorial pathogenesis of hypertension cannot be completely elucidated by physiological, genetic and conventional lifestyle risk factors. Growing evidence suggests the role of psychological stress in the pathogenesis of hypertension (1–3). Although over the last few decades, studies of psychosocial risk factors for hypertension have increased exponentially, questions about the underlying mechanisms, susceptibility and prevention have remained. Hence the present review explores the recent findings on psychosocial risk factors, underlying mechanisms of the stress-hypertension relationship and the evidence for stress reduction interventions for hypertension so that this knowledge may be translated into clinical prevention and management of hypertension. If actual or perceived environmental demands surpass an individual’s capacity to cope, this results in psychological stress (4). This may have acute or lasting effect on emotional, behavioural and physiological responses that predispose an individual to disease, or may affect the course of disease, such as hypertension (5–7). In a 2017 meta-analysis of 11 studies encompassing 5696 participants, Liu et al. found psychosocial stress associated with an increased risk of hypertension (OR = 2.40, 95% CI = 1.65–3.49). The authors proposed cardiovascular reactivity as one of the underlying mechanisms of the stress-hypertension relationship (7). Gasperin et al., in the meta-analysis of six cohort studies including 23 comparison groups and 34,556 subjects, reported 21% more likelihood of developing hypertension in individuals who had greater responses to stressor tasks compared to those with lessor responses (1). Carroll et al. found high systolic blood pressure (SBP) reactivity to acute mental stress associated with increased risk of developing hypertension after a 12-year follow up (8). It has been suggested that repeated episodes of exaggerated cardiovascular reactivity could contribute to hypertension by promoting vascular remodelling (9). Along with increased cardiovascular reactivity, the delayed recovery to the pre-stress level is considered another possible pathway to high blood pressure (BP). In a meta-analysis of 31 cohort studies, Chida and Steptoe found that greater stress reactivity and poor stress recovery are associated longitudinally with elevated BP, hypertension, left ventricular mass, subclinical atherosclerosis and clinical cardiac events (10). Based on 30 years of epidemiological studies, there is a range of well-documented psychosocial stress risk factors for hypertension. These include anxiety (11), depression (12,13), anger (14), posttraumatic stress (15), low social support (16,17), occupational stress (18,19), low socioeconomic status (20), racial discrimination (21,22) and marital distress (23,24). These psychosocial risk factors are discussed in detail in Chapter 18 in this volume
... Il Biofeedback è stato adoperato in generale nella riabilitazione cardiologica (Climov et al. 2017) nonchè per la riduzione della pressione arteriosa in pazienti affetti da Ipertensione (Lin et al. 2012). In questi casi lo strumento è stato adoperato per modulare il battito car-diaco, lavorando direttamente sul sistema nervoso autonomo ed in particolare sulla variabilità del battito cardiaco (HRV-Biofeedback) secondo il metodo classico. ...
Article
This article presents the results of a research conducted on 18 patients with Acute Coronary Syndrome (SCA). These subjects, divided into two groups, received, besides clinical treatment, an educational–rehabilitative intervention through the use of Biofeedback. In particular, the control group received a "traditional bio–feedback treatment", while the experimental group was equally subjected to the biofeedback technique, but with an "educational protocols aimed at wellness education". The biofeedback technique, aimed to controlling the activation of the Autonomic Nervous System in stressful conditions, has proved to be partly useful in the treatment of patients. In line with pedagogy of Wellness (Iavarone 2007), subjects educated to promote their own personal wellness improve compliance with therapies, structure more adequate coping strategies, manifest greater resilience. Results show that both groups had an equal benefit from the physiological point of view, moreover, subjects of the experimental group has modified their own body awareness, confirming the validity of an educational approach "body–centered" aimed at the patient's well– being. Italiano Questo articolo presenta i risultati di una ricerca condotta su 18 pazienti affetti da Sindrome Coronarica Acuta (SCA). I soggetti, suddivisi in due gruppi, hanno ricevuto, oltre il trattamento clinico, un intervento educativo–riabilitativo mediante impiego del Biofeedback. In particolare, il gruppo controllo ha ricevuto un “trattamento bio–feedback tradizionale”, mentre il gruppo sperimentale è stato ugualmente sottoposto alla tecnica del biofeedback, ma con un “protocollo educativo finalizzato all’educazione al benessere”. La tecnica del biofeedback, finalizzata a controllare l’attivazione del Sistema Nervoso Autonomo in condizioni di stress, si è rivelata particolarmente utile nel trattamento dei pazienti. In coerenza al modello della Pedagogia del Benessere (Iavarone 2007) soggetti educati a promuovere il proprio personale benessere migliorano la compliance alle terapie, strutturano più adeguate strategie di coping, manifestano maggiore resilienza. I risultati mostrano che, nonostante entrambi i gruppi abbiano ottenuto un uguale beneficio dal punto di vista fisiologico, il gruppo sperimentale ha, non solo potenziato le competenze descritte, ma complessivamente aumentato la propria consapevolezza corporea, ribadendo la validità di un approccio educativo–terapeutico embodied– centred. volto al benessere del paziente.
... Importantly, decreased HRV has been linked to poor general health in a population-based study of middle-aged men and women (18), and multiple reports have demonstrated an independent link between lower cardiac PNS activity and increased cardiovascular risk (18,36,57). In the general non-PTSD population, prehypertension is characterized by decreased HRV compared with normotension (13,37,39,50) and by a decline in cardiac parasympathetic tone and an increase in norepinephrine secretion (17). Although prehypertension as defined by JNC 7 is currently not treated pharmacologically in the clinical setting, there is growing recognition that even the modest elevations in resting BP characteristics of prehypertension are independently linked to an increased risk for development of overt hypertension and CVD (1,38). ...
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Posttraumatic stress disorder (PTSD) is characterized by increased sympathetic nervous system (SNS) activity, blunted parasympathetic nervous system (PNS) activity, and impaired baroreflex sensitivity (BRS) that contribute to accelerated cardiovascular disease (CVD). PTSD patients also have chronic stress-related elevations in resting blood pressure (BP), often in the prehypertensive range; yet, it is unclear if elevated resting blood pressure (ERBP) augments these autonomic derangements in PTSD. We hypothesized that compared to normotensive PTSD (N-PTSD), those with ERBP (E-PTSD) have further increased SNS, decreased PNS activity and impaired BRS at rest, and exaggerated SNS reactivity, PNS withdrawal, and pressor responses during stress. In 16 E-PTSD and 17 matched N-PTSD, we measured continuous BP, ECG, muscle sympathetic nerve activity (MSNA), and heart rate variability (HRV) markers reflecting cardiac PNS activity (standard deviation of R-R intervals (SDNN), root mean square of differences in successive R-R intervals (RMSSD), and high frequency power (HF)) during five minutes of rest and three minutes of mental arithmetic. Resting MSNA (p=0.943), sympathetic BRS (p=0.189) and cardiovagal BRS (p=0.332) were similar between groups. However, baseline SDNN (56±6 vs 78±8ms, p=0.019), RMSSD (39±6 vs 63±9 ms, p=0.018), and HF (378±103 vs 693±92 ms2, p=0.015) were lower in E-PTSD vs. N-PTSD. During mental stress, the systolic blood pressure response (p=0.011) was augmented in E-PTSD. While MSNA reactivity was not different (p>0.05), the E-PTSD group had an exaggerated reduction in HRV during mental stress (p<0.05). PTSD with ERBP have attenuated resting cardiac PNS activity, coupled with exaggerated BP reactivity and PNS withdrawal during stress.
... 97 HRVB has been found to reduce blood pressure in prehypertensive individuals and proved to be superior to slow abdominal breathing. 98 In another group of prehypertensive patients, beneficial effects on blood pressure and HRV parameters of HRVB were maintained when stressors were applied. 99 However, in an early study in mildly hypertensive patients, the HRVB has been found to be ineffective in reducing blood pressure values. ...
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Depressive disorders are among the most important health problems and are predicted to constitute the leading cause of disease burden by the year 2030. Aside significant impact on quality of life, psychosocial well-being and socioeconomic status of affected patients, depression is associated with impaired cardiovascular health and increased mortality. The link between affective and cardiovascular disease has largely been attributed to dysregulation of the autonomic nervous system resulting in a chronic shift toward increased sympathetic and decreased parasympathetic activity and, consecutively, cardiac dysautonomia. Among proposed surrogate parameters to capture and quantitatively analyze this shift, heart rate variability (HRV) and baroreflex sensitivity have emerged as reliable tools. Attenuation of these parameters is frequently seen in patients suffering from depression and is closely linked to cardiovascular morbidity and mortality. Therefore, diagnostic and therapeutic strategies were designed to assess and counteract cardiac dysautonomia. While psychopharmacological treatment can effectively improve affective symptoms of depression, its effect on cardiac dysautonomia is limited. HRV biofeedback is a non-invasive technique which is based on a metronomic breathing technique to increase parasympathetic tone. While some small studies observed beneficial effects of HRV biofeedback on dysautonomia in patients with depressive disorders, larger confirmatory trials are lacking. We reviewed the current literature on cardiac dysautonomia in patients suffering from depression with a focus on the underlying pathophysiology as well as diagnostic workup and treatment.
... Heart rate variability (HRV) is a naturally occurring variation in heart rate, which is modulated by the ANS and the higher brain centers that connect with it. Based on the connection between emotions and these physiological mechanisms, HRV can reflect an individual's emotional state (14), and furthermore, there is evidence that manipulation of HRV via HRV-BF can have beneficial clinical effects on conditions such as hypertension (15)(16)(17), and aspects of emotional dysregulation such as anxiety (18)(19)(20)(21)(22)(23)(24)(25)(26), hostility (27,28), and depression (25, [29][30][31]. Individuals with greater ability to regulate emotions have been shown to have greater levels of resting HRV (32,33), a phenomenon referred to as resonance (34), and this high amplitude oscillation of heart rate is attained only at the system's resonant frequencies (35). ...
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Primary objective: To examine the efficacy of heart rate variability biofeedback (HRV-BF) to treat emotional dysregulation in persons with acquired brain injury. Design: A secondary analysis of a quasi-experimental study which enrolled 13 individuals with severe chronic acquired brain injury participating in a community-based programme. Response-to-treatment was measured with two HRV resonance indices (low frequency activity [LF] and low frequency/high frequency ratio [LF/HF]). Main outcome: Behavior Rating Inventory of Executive Function-informant report (emotional control subscale [EC]). Results: Results show significant correlation between LF and EC with higher LF activity associated with greater emotional control; the association between LF/HF pre-post-change score and EC is not statistically significant. A moderation model, however, demonstrates a significant influence of attention on the relation between LF/HF change and EC when attention level is high, with an increase in LF/HF activity associated with greater emotional control. Conclusions: HRV-BF is associated with large increases in HRV, and it appears to be useful for the treatment of emotional dysregulation in individuals with severe acquired brain injury. Attention training may enhance an individual's emotional control.
... Lower HRV is connected with impaired glucose and lipid metabolism 16 . In contrary to previous findings of connection of lowered HRV even in the early stage on hypertension 17 , no correlation was found in this study regarding increased blood pressure and HRV, after adjustment for age. Previous data is showing that HRV is decreasing with age 18 . ...
... Grandjean introduced the concept of mental fatigue 2 , which Thiffault et al. 3 expounded upon further. Mental fatigue can be described as reduced motivation caused by factors such as lethargy and cognitive impairment [4][5][6][7][8] resulting from heavy mental work, excessive nervous system tension, or long durations of monotonous and tedious work 4,[9][10][11][12][13] . Mental fatigue leads to reduced goal-directed attention and flexibility of behavioral responses, as well as an increase in automatic behavior 14 , negatively impacting the training time required to achieve manual dexterity 15 . ...
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Mental fatigue increases risk-taking behavior. Using data collected between June 15 and August 6, 2020, this study investigates the impact of miners’ mental fatigue on risk decision-making to improve risk prevention and prediction abilities, and to reduce the occurrence of coal mine safety accidents. A total of 273 and 33 people participated in the preliminary and formal experiments, respectively. The participants, coal miners, visited a lab thrice to complete the pre-experiment, Balloon Analog Risk Task (BART), and Iowa Gambling Task (IGT). On the BART, mental fatigue displayed a significantly positive association with risk preference. On the IGT, as mental fatigue increased, net scores continuously decreased, while the frequency of making unfavorable decisions and the probability of taking risks increased. The BART value had no or weak correlations with the net score. Results suggest that mental fatigue leads to an increasing propensity to take risks. Therefore, regarding coal mine safety management, further attention is necessary concerning miners’ mental health, addressing mental fatigue, increasing rest time, and reducing night work. Furthermore, reasonable diet, improved working environments, and a positive attitude toward work should be promoted to reduce or eliminate mental fatigue and avoid decision-making errors that could cause accidents.
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Volitional control of breathing often leads to excessive ventilation (hyperventilation) among untrained individuals, which disrupts CO2 homeostasis and may elicit a set of undesirable symptoms. The present study investigated whether seven days of training without any anti-hyperventilation instructions improves CO2 homeostasis during paced breathing at a frequency of 0.1 Hz (6 breaths/minute). Furthermore, the present study investigated the effects of training on breathing-related changes in affective state to examine the hypothesis that training improves the influence of slow paced breathing on affect. A total of 16 participants performed ten minutes of paced breathing every day for seven days. Partial pressure of end-tidal CO2 (PetCO2), symptoms of hyperventilation, affective state (before and after breathing), and pleasantness of the task were measured on the first, fourth, and seventh days of training. Results showed that the drop in PetCO2 significantly decreased with training and none of the participants experienced a drop in PetCO2 below 30 mmHg by day seven of training (except one participant who already had PetCO2 below 30 mmHg during baseline), in comparison to 37.5% of participants on the first day. Paced breathing produced hyperventilation symptoms of mild intensity which did not decrease with training. This suggests that some participants still experienced a drop of PetCO2 that was deep enough to produce noticeable symptoms. Affective state was shifted towards calmness and relaxation during the second and third laboratory measurements, but not during the first measurement. Additionally, the breathing task was perceived as more pleasant during subsequent laboratory measurements. The obtained results showed that training paced breathing at 0.1 Hz led to decrease in hyperventilation. Furthermore, the present study suggests that training paced breathing is necessary to make the task more pleasant and relaxing.
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Limitations of current depression treatments may arise from a lack of knowledge about unique psychophysiological processes that contribute to depression across the full range of presentations. This study examined how individual variations in heart rate (HR) and heart rate variability (HRV) are related to depressive symptoms across normative and clinical populations in152 young adults (aged 18-35 years). Moderating effects of sex and antidepressant medication status were considered. Electrocardiogram data were collected during “vanilla” baseline and in response to positive and negative emotional cues. Linear regressions and repeated-measures mixed models were used to assess the relationships between Beck Depression Inventory-II (BDI-II) scores, sex, antidepressant use, and cardiovascular outcomes. Baseline models yielded significant main effects of BDI-II and sex on HR and significant interactions between antidepressant medication status and BDI-II on HRV outcomes. The main effects of BDI-II and sex on HR were no longer significant after controlling for cardiorespiratory fitness. Participants who denied current antidepressant use (n=15) exhibited a negative association and participants who endorsed current antidepressant (n=137) use exhibited a positive association between BDI-II scores and HRV. Emotional reactivity models were largely non-significant with the exception of a significant main effect of antidepressant medication status on high-frequency HRV reactivity. Results indicated antidepressant medication use may moderate the relationship between depression severity and cardiovascular functioning, but this requires replication given the modest proportion of medicated individuals in this study. Overall, findings suggest cardiovascular processes and cardiorespiratory fitness are linked to depression symptomatology and may be important to consider in depression treatment.
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Effects of a behavioral intervention using biofeedback on myocardial blood flow changes during mental stress in patients with coronary artery disease. Protocol document provides detailed description of each intervention applied to patients with CAD. (PDF)
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Slow breathing (SLOWB) is recommended for use as an adjuvant treatment for hypertension. However, the extent to which blood pressure (BP) responses to SLOWB differ between men and women are not well-established. Therefore, we tested the hypothesis that an acute bout of SLOWB would induce larger decreases in BP in males than females, given that males typically have higher resting BP. We also examined autonomic contributors to reduced BP during SLOWB, that is, muscle sympathetic nerve activity (MSNA), and spontaneous cardiovagal (sequence method) and vascular sympathetic baroreflex sensitivity (BRS). We tested normotensive females (n=10, age: 22±2y, BMI: 22±2kg/m ² ) and males (n=12, 23±3y, 26±4kg/m ² ). Subjects were tested at baseline and during the last 5-min of a 15-min RESPeRATE-guided SLOWB session. Overall, SLOWB reduced systolic BP (SBP) by 3.2±0.8 mmHg (main effect, p<.01). Females had lower SBP (main effect, p=.02); we observed no interaction between sex and SLOWB. SLOWB also reduced MSNA burst incidence by -5.0±1.4 bursts/100hb (main effect, p<.01). Although females tended to have lower burst incidence (main effect, p=.1), there was no interaction between sex and SLOWB. Cardiovagal BRS improved during SLOWB (21.0 vs 36.0 ms/mmHg, p=.03) with no effect of sex. Despite lower overall BP in females, our data support a lack of basement effect on SLOWB-induced reductions in BP, as SLOWB was equally effective in reducing BP in males and females. Our findings support the efficacy of the RESPeRATE device for reducing BP in both sexes, even in young, normotensive individuals.
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Background and Objectives Though reduced cardiovagal modulation accompanies adult IBS, adolescents with functional gastrointestinal disorders (FGID) have not been studied. We aim to investigate whether adolescents with FGID have reduced cardiovagal modulation. Methods After 10‐minute supine rest, we recorded ECG for 5‐minute supine and 5‐minute standing without support in healthy and FGID‐affected adolescents. After analysis with Kubios 2.2 for high‐frequency (hf) and low‐frequency (lf) heart rate variability (HRV), Wilcoxon signed‐ranks test compared individual paired supine and standing HRV data, while Kruskal‐Wallis and Mann‐Whitney U tests compared HRV across groups. Results A total of 50 FGID subjects (90% females; median age 17 years [range 11‐21]) and 22 healthy comparison group (HC) (59% females; median age 14 years [range 10‐18]) participated. Both absolute and relative supine hfHRV exceeded standing in both groups. Absolute supine lfHRV was higher than standing in FGID patients and not in HCs, while relative supine lfHRV power was actually lower in both groups. Compared to HC, FGID group showed significantly lower absolute HRV, while relative HRV did not differ between groups. Conclusions Cardiovagal modulation is lower in adolescents with FGID. This difference impacts these subjects significantly. Whether this finding reflects a cause or a consequence of FGID is unknown.
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We performed a systematic and meta analytic review of heart rate variability biofeedback (HRVB) for various symptoms and human functioning. We analyzed all problems addressed by HRVB and all outcome measures in all studies, whether or not relevant to the studied population, among randomly controlled studies. Targets included various biological and psychological problems and issues with athletic, cognitive, and artistic performance. Our initial review yielded 1868 papers, from which 58 met inclusion criteria. A significant small to moderate effect size was found favoring HRVB, which does not differ from that of other effective treatments. With a small number of studies for each, HRVB has the largest effect sizes for anxiety, depression, anger and athletic/artistic performance and the smallest effect sizes on PTSD, sleep and quality of life. We found no significant differences for number of treatment sessions or weeks between pretest and post-test, whether the outcome measure was targeted to the population, or year of publication. Effect sizes are larger in comparison to inactive than active control conditions although significant for both. HRVB improves symptoms and functioning in many areas, both in the normal and pathological ranges. It appears useful as a complementary treatment. Further research is needed to confirm its efficacy for particular applications.
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The quantitative analysis of electroencephalogram (qEEG) is a suitable tool for mental fatigue (MF) assessment. Here, we evaluated the effects of MF on behavioral performance and alpha power spectral density (PSD) and the association between early alpha PSD reactivity and long-term behavioral MF impairments. Nineteen right-handed adults (21.21 ± 1.77 years old) had their EEG measured during five blocks of the visual oddball paradigm (~ 60 min). A paired t-test was used to compare first and last block values of cognitive performance and alpha PSD. The sample was divided into high (HAG) and low alpha group (LAG) by early alpha PSD median values. The behavioral performance of the HAG and LAG was compared across the blocks by a two-way ANOVA with repeated measures (groups and blocks). MF impairs general behavioral performance and increases alpha PSD. The HAG presents more behavioral impairment when compared to LAG across the task. Simple linear regression between early alpha PSD and behavioral performance across the task can predict 19 to 39% of variation in general behavior impairment by MF. In conclusion, MF induction impairs general behavioral and increases alpha PSD. The other finding was that higher alpha PSD reactivity is associated to higher long-term behavioral impairments of MF. This work contributes to existing knowledge of MF by providing evidence that the possibility of investigating early electrophysiological biomarkers to predict long-term MF impairments.
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Baroreceptors are mechanosensitive elements of the peripheral nervous system that maintain homeostasis by coordinating physiologic responses to external and internal stimuli. While it is recognized that carotid and cardiopulmonary baroreceptor reflexes modulate autonomic output to mitigate excessive fluctuations in arterial blood pressure and to maintain intravascular volume, increasing evidence suggests that baroreflex pathways also project to key regions of the central nervous system that regulate somatosensory, somatomotor, and central nervous system arousal. In addition to maintaining autonomic homeostasis, baroreceptor activity modulates the perception of pain, as well as neuroimmune, neuroendocrine, and cognitive responses to physical and psychologic stressors. This review summarizes the role that baroreceptor pathways play in modulating acute and chronic pain perception. The contribution of baroreceptor function to postoperative outcomes is also presented. Finally, methods that enhance baroreceptor function, which hold promise in improving postoperative and pain management outcomes, are presented.
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Objective: During voyages, seafarers experience psychological problems that act to decrease operational safety. Psychological problems in seafarers can lead to changes in functional brain networks. This study investigated the low-frequency brain effective connectivity (EC) in seafarers during voyages by using the coupling strength (CS) of functional near-infrared spectroscopy (fNIRS) imaging. Approach: This study recruited 15 seafarers (seafarer group) working on a container ship and 15 healthy age-matched controls (control group). The EC was assessed using dynamic Bayesian inference (DBI) of the oxygenated hemoglobin concentration (delta HbO2) as measured through a 14-channel fNIRS system. These channels covered the left and right prefrontal cortices (LPFC/RPFC), left and right motor cortices (LMC/RMC), and left and right occipital lobes (LOL/ROL). Main results: The EC levels of LPFC to RMC (F = 4.239, p = 0.049), LPFC to ROL (F = 5.385, p = 0.028), LOL to RPFC (F = 11.128, p = 0.002), ROL to RPFC (F = 10.714, p = 0.003) and LMC to ROL (F= 6.136, p = 0.02) were significantly lower in the seafarer group than in the control group. Correlation analysis revealed that the patient health questionnaire-9 (PHQ-9) scores were positively correlated with the systolic blood pressure (SBP) values, delta HbO2 values and EC levels, respectively. Meanwhile, the correlation analysis revealed that the SBP values significantly positively correlated with the CS values. Significance: Decreased EC levels may be a marker of psychological subhealth in seafarers. The approach combines fNIRS and PHQ-9 scores, providing a quantitative method for the assessment of mental health problems and further help with better rehabilitation designs in seafarers during voyages.
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This study examines whether twelve sessions of heart rate variability biofeedback training would improve vagally mediated heart rate variability. If so, it would go some way in explaining why breathing based interventions reduces clinical symptoms and improves non-clinical performance outcomes. Methods: Thirty participants (N = 30, Nfemale = 13) aged 14–13-year-old talented athletes from a sport specialist school in SE London UK, were randomly divided into three groups, a control group, a psychology skills training combined with heart rate variability biofeedback training group, and a heart rate variability biofeedback only group. For the combined group a variety of typical psychological skill training techniques were also used. Results: Paired participant t test and the Wilcoxon Signed Rank test found non-significant differences between pre- and post-intervention measurements of SDNN, HF Log, pNN50 and RMSSD Log heart rate variability. Non-significant results remained even after pooling the biofeedback training groups (n = 19). Conclusion: Our results do not indicate that beneficial effects associated with focused breathing training can be attributed to improved vagal tone. Further investigation into the underlying mechanisms of the benefits of focused breathing techniques is necessary to maximize clinical and non-clinical outcomes.
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Background: Deep diaphragmatic breathing, also called belly breathing, is a popular behavioral intervention that helps children cope with anxiety, stress, and their experience of pain. Combining physiological monitoring with accessible mobile technology can motivate children to comply with this intervention through biofeedback and gaming. These innovative technologies have the potential to improve patient experience and compliance with strategies that reduce anxiety, change the experience of pain, and enhance self-regulation during distressing medical procedures. Objective: The aim of this paper was to describe a simple biofeedback method for quantifying breathing compliance in a mobile smartphone app. Methods: A smartphone app was developed that combined pulse oximetry with an animated protocol for paced deep breathing. We collected photoplethysmogram data during spontaneous and subsequently paced deep breathing in children. Two measures, synchronized respiratory sinus arrhythmia (RSAsync) and the corresponding relative synchronized inspiration/expiration heart rate ratio (HR-I:Esync), were extracted from the photoplethysmogram. Results: Data collected from 80 children aged 5-17 years showed a positive RSAsync effect in all participants during paced deep breathing, with a median (IQR; range) HR-I:Esync ratio of 1.26 (1.16-1.35; 1.01-1.60) during paced deep breathing compared to 0.98 (0.96-1.02; 0.82-1.18) during spontaneous breathing (median difference 0.25, 95% CI 0.23-0.30; P<.001). The measured HR-I:Esync values appeared to be independent of age. Conclusions: An HR-I:Esync level of 1.1 was identified as an age-independent threshold for programming the breathing pattern for optimal compliance in biofeedback.
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Heart rate variability (HRV) biofeedback, referring to slow‐paced breathing (SPB) realized while visualizing a heart rate, HRV, and/or respiratory signal, has become an adjunct treatment for a large range of psychologic and medical conditions. However, the underlying mechanisms explaining the effectiveness of HRV biofeedback still need to be uncovered. This study aimed to disentangle the specific effects of HRV biofeedback from the effects of SPB realized alone. In total, 112 participants took part in the study. The parameters assessed were emotional (valence, arousal, and control) and perceived stress intensity as self‐report variables and the root mean square of the successive differences (RMSSD) as a physiologic variable. A main effect of condition was found for emotional valence only, valence being more positive overall in the SPB‐HRVB condition. A main effect of time was observed for all dependent variables. However, no main effects for the condition or time x condition interaction effects were observed. Results showed that for PRE and POST comparisons (referring, respectively, to before and after SPB), both SPB‐HRVB and SPB‐NoHRVB conditions resulted in a more negative emotional valence, lower emotional arousal, higher emotional control, and higher RMSSD. Future research might investigate psychophysiological differences between SPB‐HRVB and SPB‐NoHRVB across different time periods (e.g., long‐term interventions), and in response to diverse psychophysiological stressors. Slow‐paced breathing (SPB) is usually realized using a biofeedback device. Our findings show for the first time that a short SPB session (5 min) realized without any biofeedback device have mostly similar psychophysiological effects compared with SPB realized with biofeedback (i.e., displaying the heart rate signal), with the exception of a more positive emotional valence in the biofeedback condition.
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Atherosclerosis remains the leading cause of mortality and morbidity worldwide characterized by the deposition of lipids and fibrous elements in the form of atheroma plaques in vascular areas which are hemodynamically overloaded. The global burden of atherosclerotic cardiovascular disease is steadily increasing and is considered the largest known non-infectious pandemic. The management of atherosclerotic cardiovascular disease is increasing the cost of health care worldwide, which is a concern for researchers and physicians and has caused them to strive to find effective long-term strategies to improve the efficiency of treatments by managing conventional risk factors. Primary prevention of atherosclerotic cardiovascular disease is the preferred method to reduce cardiovascular risk. Fasting, a Mediterranean diet, and caloric restriction can be considered useful clinical tools. The protective impact of physical exercise over the cardiovascular system has been studied in recent years with the intention of explaining the mechanisms involved; the increase in heat shock proteins, antioxidant enzymes and regulators of cardiac myocyte proliferation concentration seem to be the molecular and biochemical shifts that are involved. Developing new therapeutic strategies such as vagus nerve stimulation, either to prevent or slow the disease’s onset and progression, will surely have a profound effect on the lives of millions of people. Keywords: endothelial dysfunction; sympathetic nervous system; caloric restriction; fasting; diet; physical exercise; vagus nerve stimulation
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Resonance breathing (RB) has been shown to benefit health and performance within clinical and non-clinical populations. This is attributed to its baroreflex stimulating effect and the concomitant increase in cardiac vagal activity (CVA). Hence, developing methods that strengthen the CVA boosting effect of RB could improve its clinical effectiveness. Therefore, we assessed whether supplementing RB with coherent pelvic floor activation (PRB), which has been shown to entrain the baroreflex, yields stronger CVA than standard RB. N = 32 participants performed 5-min of RB and PRB, which requires to recruit the pelvic floor during the complete inspiratory phase and release it at the initiation of the expiration. CVA was indexed via heart rate variability using RMSSD and LF-HRV. PRB induced significantly larger RMSSD (d = 1.04) and LF-HRV (d = 0.75, ps < .001) as compared to RB. Results indicate that PRB induced an additional boost in CVA relative to RB in healthy individuals. However, subsequent studies are warranted to evaluate whether these first findings can be replicated in individuals with compromised health, including a more comprehensive psychophysiological assessment to potentially elucidate the origin of the observed effects. Importantly, longitudinal studies need to address whether PRB translates to better treatment outcomes.
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The aims of this study were to investigate the efficacy of heart rate variability biofeedback (HRVBFB) intervention in terms of reducing craving, severity of dependence, and rate of positive methamphetamine urine testing in men taking part in a methamphetamine use disorder outpatient treatment program. Sixty-one adult men received either HRVBFB treatment plus treatment as usual (TAU) over four weeks or TAU only. Men receiving HRVBFB showed significantly greater reductions in craving, dependence severity, and the rate of positive methamphetamine urine testing at the end of the intervention and four weeks of follow-up. The analyses further showed that the levels of craving and dependence severity at treatment entry were predictive of changes in craving and dependence severity at the end of treatment and follow-up, respectively. The baseline status of a positive methamphetamine urine test only predicted a positive methamphetamine urine test at the end of treatment, not at the end of the follow-up period. Our results showed HRVBFB intervention has merits as an adjunct treatment to ameliorate cravings and reduce the severity of dependence experienced by persons with methamphetamine use disorder. An added value of HRVBFB intervention is the fact that it can be easily and affordably implemented in everyday life.
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This paper reviews the published work of me along with my students and close colleagues on the topic of heart rate variability biofeedback (HRVB). It includes early research by Vaschillo documenting resonance characteristics of the baroreflex system that causes large oscillations in heart rate when breathing at resonance frequency, research on heart rate variability as a marker of parasympathetic stress response in asthma, and HRVB as a treatment for asthma and depression. Many questions about HRVB remain unresolved, and important questions for future research are listed.
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Resonance breathing (RB) has been shown to improve psychophysiological health and performance within clinical and non-clinical populations. This is attributed to its baroreflex stimulating effects and the concomitant increase in cardiac vagal activation (CVA). Hence, developing methods that strengthen the CVA boosting effect of RB could improve its clinical effectiveness. Therefore, we assessed whether supplementing RB with coherent pelvic floor activation (PRB), which has been shown to entrain the baroreflex, yields stronger CVA than standard RB. N = 32 participants performed 5-minutes of RB and PRB, which requires to recruit the pelvic floor during inhalation and release it at the initiation of the expiration. CVA was indexed via heart rate variability using RMSSD and LF-HRV. PRB induced significantly larger RMSSD (d = 1.04) and LF-HRV (d = 0.75, ps < .001) compared to RB. Our results indicate that coherent pelvic floor recruitment during RB enhances its CVA boosting effects in healthy individuals. However, subsequent studies are warranted to evaluate whether these first findings can be replicated in individuals with compromised health, including a more comprehensive psychophysiological assessment to potentially elucidate the origin of the promising effects. Importantly, longitudinal studies need to address whether the additional CVA during PRB translates to better treatment outcomes.
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Psychological stress is a well-established risk factor for cardiovascular disease (CVD). Heart rate variability (HRV)-biofeedback could significantly reduce stress levels and improve autonomic nervous system function and cardiovascular endpoints. We aimed to systematically review the literature to investigate the impact of HRV modulation through HRV-biofeedback on clinical outcomes in patients with CVD. A literature search was performed in the following databases: MEDLINE (PubMed), Embase, and Cochrane from the inception until 1 October 2021. Patients in the HRV-biofeedback group had significantly lower rates of all-cause readmissions than patients who received psychological education (respectively, p = 0.028 and p = 0.001). Heart failure following HRV-biofeedback displayed an inverse association with stress and depression (respectively, p = 0.022 and p = 0.033). When stratified according to left ventricular ejection fraction (LVEF), patients with LVEF ≥ 31% showed improved values of the 6 min walk test after HRV-biofeedback interventions (p = 0.05). A reduction in systolic and diastolic blood pressure associated with HRV-biofeedback was observed (p < 0.01) in pre-hypertensive patients. HRV-biofeedback had beneficial effects on different cardiovascular diseases documented in clinical trials, such as arterial hypertension, heart failure, and coronary artery disease. A standard breathing protocol should be applied in future studies to obtain equivalent results and outcomes. However, data regarding mortality in patients with coronary artery disease are scarce and need further research.
Article
Biofeedback is a technique that involves feedback of physiological and biomechanical parameters enabling the user to learn how to consciously regulate these responses. Biofeedback training has been a tool for helping students improve academic performance and aiding in the treatment of clinical conditions such as mental, behavioral, and neurodevelopmental disorders. This study aimed at conducting a systematic review of the literature published on the use of biofeedback techniques among students from elementary school, high school, and college. A bibliographic search was conducted in the electronic database MEDLINE. The descriptors “biofeedback” and “students” were used and only articles published between 2010 and 2020 were selected. After applying inclusion and exclusion criteria, 14 articles, all randomized controlled trials, were analyzed: four studies had students from elementary school as participants, one article had students from high school as volunteers, and nine studies had students from college as participants. Among the analyzed literature, eight articles made use of neurofeedback, heart rate variability (HRV) biofeedback was the instrument chosen in five of the examined studies, and one article made use of biomechanical feedback. Results suggest that biofeedback techniques are valuable tools in interventions involving students from all levels of formal education, both as a therapeutic instrument, and as a resource for healthy individuals to enhance performance and better quality of life.
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This study assessed the effects of aerobic exercise on cardiac autonomic nervous system function (based on heart rate variability [HRV]) and executive function among individuals with methamphetamine use disorder (MUD). We further examine the role of autonomic nervous system control in aerobic exercise (assessed via cardiopulmonary fitness) and executive function. A total of 330 individuals with MUD were randomly divided into exercise (n = 165) and control (n = 165) groups, who underwent eight-week aerobic exercise/health education program consisting of five 60–minute sessions a week. The outcome measures included cardiopulmonary fitness, HRV time-domain and frequency-domain parameters, and executive function. Our statistical analyses comprised repeated-measures analyses of variance, correlation analyses, and mediation and moderation effect tests. The results indicated that aerobic exercise could simultaneously improve autonomic nervous system function and executive function among individuals with MUD. Moreover, the changes in cardiopulmonary fitness, high frequency HRV, and executive function were positively correlated. HRV did not significantly mediate the relationship between aerobic exercise and executive function; however, it did have a moderating effect, which was eliminated after adjusting for demographic and drug-use covariates. Among the covariates, age was the greatest confounder and was inversely proportional to cardiopulmonary function, HRV, and executive function. Cardiac autonomic nervous system function exerted a moderating, rather than a mediating, effect on the relationship between aerobic exercise and executive function. However, this potential effect was largely influenced by covariates, particularly age.
Article
Objective: Currently, BP measurement devices are mainly cuff-based which are not portable or convenient for users. To simplify the measurement of BP, this paper proposed a new framework for noninvasive BP estimation using single-channel photoplethysmography (PPG) signal. Methods: Various PPG features that may be related to BP were extracted and a filter-wrapper collaborated feature selection method was used for rejecting irrelevant and redundant features. The features that maximize the correlation with BP were finally selected as the BP-oriented improved feature subset (IFS), and a new LASSO-LSTM model was designed to estimate BP from the IFS. Results: Experiments were conducted on a public dataset and a self-collected clinical dataset, respectively. Results demonstrated that the proposed method is superior to previously reported methods in the literature, giving a mean absolute error of 4.95 mmHg for systolic blood pressure (SBP) and 3.15 mmHg for diastolic blood pressure (DBP) which complies with the standard of AAMI. Conclusion: The proposed filter-wrapper collaborated feature selection method could effectively reject weak correlation and redundant features, and the designed LASSO-LSTM model is capable of learning complicated nonlinear relations between the selected IFS and BP. The proposed method shows improved accuracy of noninvasive BP estimation.
Article
Introduction Systemic arterial hypertension (SAH) is considered a multifactorial disease characterized by a persistent increase in blood pressure levels. Currently, the efficient control of blood pressure is achieved by both the use of pharmacological therapy and the control of risk factors. In addition, the use of biofeedback (BFB) as a non-pharmacological strategy represents a promising therapy. Objective: This study aims to evaluate the effects of BFB on systolic and diastolic blood pressure levels, as well as on environmental and psychosocial factors in patients with essential SAH. Methods: A systematic review (SR) of the literature was carried out in English and Portuguese using the following databases: SCIELO, LILACS, CINAHL, Cochrane, and PubMed. The search strategy included a mix of terms for the key concepts Biofeedback, Heart Rate Variability, Psychophysiological Feedback, and Heart Biofeedback. Studies were analyzed independently. Results: The included studies evaluated a total of 462 subjects of both sexes. The meta-analysis revealed that BFB significantly elicited greater blood pressure control, mainly improving DBP levels (Z = 2.15; P = 0.03). Discussion: Besides improvement in DBP readings post-intervention, BFB also resulted in better disease-related environmental and psychosocial factors, such as reduced stress levels. The magnitude of effect did not appear to depend on the type of BFB applied. Conclusion: This SR demonstrated that BFB with visual and/or auditory information is a complementary option to pharmacological treatment in the management of individuals with systolic and diastolic arterial hypertension. Moreover, the use of this adjuvant therapy seems to facilitate better DPB control.
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Purpose of Review: Addiction and excessive substance use contribute to poor mental and physical health. Much research focuses tightly on neural underpinnings and centrally-acting interventions. To broaden this perspective, this review focuses on bidirectional pathways between the brain and cardiovascular system that are well-documented and provide innovative, malleable targets to bolster recovery and alter substance use behaviors. Recent Findings: Cardiovascular signals are integrated via afferent pathways in networks of distributed brain regions that contribute to cognition, as well as emotion and behavior regulation, and are key antecedents and drivers of substance use behaviors. Heart rate variability (HRV), a biomarker of efficient neurocardiac regulatory control, is diminished by heavy substance use and substance use disorders. Promising evidence-based adjunctive interventions that enhance neurocardiac regulation include HRV biofeedback, resonance paced breathing, and some addiction medications. Summary: Cardiovascular communication with the brain through bidirectional pathways contributes to cognitive and emotional processing but is rarely discussed in addiction treatment. New evidence supports cardiovascular-focused adjunctive interventions for problematic substance use and addiction.
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We aimed to determine the efficacy of an 8-week direct blood pressure (BP) biofeedback training program for prehypertensive or stage I hypertensive patients with a particular focus on the impact of the authenticity of feedback signals on the efficacy of BP regulation. This study has a randomized, double-blind, parallel-group design. Fifty-nine individuals with ages from 18 to 64 years and who met the criteria for the diagnosis of prehypertenion or stage 1 hypertension participated in this study. The participants were referrals from physicians or community-dwelling volunteers. No participants had taken antihypertensive medication within the previous 2 months prior to enrollment. The participants were randomly assigned to the biofeedback group (n = 31) trained with real-time BP feedback signals or the control group (n = 28) trained with pseudofeedback signals. The primary outcome measures were systolic BP (SBP) and diastolic BP (DBP). Systolic BP and DBP were assessed at baseline, 1 week after training (week 9), and 8 weeks after training (week 16) in both groups. Only 54 participants had week 16 data. The changes in SBP and DBP from baseline to week 9, from baseline to week 16, and from week 9 to week 16 were not significantly different between the groups (All P > 0.05). Both groups were able to significantly decrease BP after completing the training. A percentage of 45.2% of the participants in the biofeedback group and 63.0% of the participants in the control group lowered their SBP by 5 mm Hg or more at week 9. The SBP-lowering effects were also maintained for at least 8 weeks after the completion of training. The equivalent magnitude of BP reduction between the 2 study groups suggests that repeated practice in BP self-regulation was more likely responsible for the efficacy of direct BP biofeedback training than was the type of feedback signals.
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Chronic fatigue syndrome (CFS) is characterized by profound fatigue anad an array of diffuse somatic symptoms. Our group has established that impaired activation of the hypothalamic-pituitary-adrenal (HPA) axis is an essential neuroendocrine feature of this condition. The relevance of this finding to the pathophysiology of CFS is supported by the observation that the onset and course of this illness is excerbated by physical and emotional stressors. It is also notable that this HPA dysregulation differs from that seen in melancholic depression, but shares features with other clinical syndromes (e.g., fibromyalgia). How the HPA axis dysfunction develops is unclear, though recent work suggests disturbances in serotonergic neurotransmission and alterations in the activity of AVP, an important co-secretagogue that, along with CRH, influences HPA axis function. In order to provide a more refined view of the nature of the HPA dusturbance in patients with CFS, we have studied the detailed, pulsatile characteristics of the HPA axis in a group of patients meeting the 1994 CDC case criteria for CFS. Results of that work are consistent with the view that patients with CFS have a reduction of HPA axis activity due, in part, to impaired central nervous system drive. These observations provide an important clue to the development of more effective treatment to this disabling condition.
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To assess the evidence for the long-term effectiveness of biofeedback for the treatment of essential hypertension in adults. A systematic review following accepted international guidelines was conducted. Randomized controlled trials that compared biofeedback procedures with antihypertensive medication, placebo (sham biofeedback treatment), no intervention or other behavioural treatments were included. The outcome measure was change in blood pressure. The inclusion criteria were fulfilled by 36 trials. Twenty-one trials employed biofeedback treatment with no adjunctive therapy, whereas 15 others used biofeedback treatment alongside another treatment. The majority of trials were small with no posttreatment follow-up or follow-up of less than 6 months. Qualitative heterogeneity of the included studies (e.g. poor quality of the trials, differences in interventions and inconsistencies in the measurement of outcomes) meant that it was inappropriate to pool data in the form of a meta-analysis. A narrative summary of the data based on trial authors' conclusions is presented. No studies reported long-term (>12 months) follow-up of patients. Data were grouped first by treatment type and then by comparator. Trial results were variable and conflicting, demonstrating no clear benefits of biofeedback in relation to moderation of hypertension. Although there may be other reported life benefits to its use, we found no convincing evidence that consistently demonstrates the effectiveness of the use of any particular biofeedback treatment in the control of essential hypertension when compared with pharmacotherapy, placebo, no intervention or other behavioural therapies. Any future research needs to be conducted using accepted quality standards and given current guidelines for the treatment of hypertension is likely to be considered only as an adjunct to pharmacological treatment.
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The term prehypertension was coined in 1939 in the context of early studies that linked high blood pressure recorded during physical examination for life insurance purposes to subsequent morbidity and mortality. These studies demonstrated that individuals with blood pressure >120/80 mmHg, but <140/90 mmHg--the accepted value for the lower limit of the hypertensive range--had an increased risk of hypertension, cardiovascular disease and early death from cardiovascular causes. The prehypertension classification of blood pressure was later used by the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure to define a group of individuals at increased risk of cardiovascular events because of elevated blood pressure, an increased burden of other risk factors such as obesity, diabetes mellitus, dyslipidemia, and inflammatory markers, and evidence of organ damage for example, microalbuminuria, retinal arteriolar narrowing, increased carotid arterial intima-media thickness, left ventricular hypertrophy and coronary artery disease. Nonpharmacological treatment with lifestyle modifications such as weight loss, dietary modification and increased physical activity is recommended for all patients with prehypertension as these approaches effectively reduce risk of cardiovascular events. Pharmacological therapy is indicated for some patients with prehypertension who have specific comorbidities, including diabetes mellitus, chronic kidney disease and coronary artery disease.
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Power spectral analysis of heart rate variability (HRV) has been used to indicate cardiac autonomic function. High-frequency power relates to respiratory sinus arrhythmia and therefore to parasympathetic cardiovagal tone; however, the relationship of low-frequency (LF) power to cardiac sympathetic innervation and function has been controversial. Alternatively, LF power might reflect baro reflexive modulation of autonomic outflows. We studied normal volunteers and chronic autonomic failure syndrome patients with and without loss of cardiac noradrenergic nerves to examine the relationships of LF power with cardiac sympathetic innervation and baroreflex function. We compared LF power of HRV in patients with cardiac sympathetic denervation, as indicated by low myocardial concentrations of 6-[(18)F]fluorodopamine-derived radioactivity or low rates of norepinephrine entry into coronary sinus plasma (cardiac norepinephrine spillover) to values in patients with intact innervation, at baseline, during infusion of yohimbine, which increases exocytotic norepinephrine release from sympathetic nerves, or during infusion of tyramine, which increases non-exocytotic release. Baroreflex-cardiovagal slope (BRS) was calculated from the cardiac interbeat interval and systolic pressure during the Valsalva maneuver. Results. LF power was unrelated to myocardial 6-[(18)F]fluorodopamine-derived radioactivity or cardiac norepinephrine spillover. In contrast, the log of LF power correlated positively with the log of BRS (r = 0.72, P < 0.0001). Patients with a low BRS (</=3 msec/mm Hg) had low LF power, regardless of cardiac innervation. Tyramine and yohimbine increased LF power in subjects with normal BRS but not in those with low BRS. BRS at baseline predicted LF responses to tyramine and yohimbine. LF power reflects baroreflex function, not cardiac sympathetic innervation.
Article
Decreased HRV has been consistently associated with increased cardiac mortality and morbidity in HF patients. The aim of this study is to determine if a 6-week course of heart rate variability (HRV) biofeedback and breathing retraining could increase exercise tolerance, HRV, and quality of life in patients with New York Heart Association Class I-III heart failure (HF). Participants (N = 29) were randomly assigned to either the treatment group consisting of six sessions of breathing retraining, HRV biofeedback and daily practice, or the comparison group consisting of six sessions of quasi-false alpha-theta biofeedback and daily practice. Exercise tolerance, measured by the 6-min walk test (6MWT), HRV, measured by the standard deviation of normal of normal beats (SDNN), and quality of life, measured by the Minnesota Living with Congestive Heart Failure Questionnaire, were measured baseline (week 0), post (week 6), and follow-up (week 18). Cardiorespiratory biofeedback significantly increased exercise tolerance (p = .05) for the treatment group in the high (>or=31%) left ventricular ejection fraction (LVEF) category between baseline and follow-up. Neither a significant difference in SDNN (p = .09) nor quality of life (p = .08), was found between baseline and follow-up. A combination of HRV biofeedback and breathing retraining may improve exercise tolerance in patients with HF with an LVEF of 31% or higher. Because exercise tolerance is considered a strong prognostic indicator, cardiorespiratory biofeedback has the potential to improve cardiac mortality and morbidity in HF patients.
Article
Decreased vagal activity and increased sympathetic arousal have been proposed as major contributors to the increased risk of cardiovascular mortality in patients with depression. It was aim of the present study to assess the feasibility of using heart rate variability (HRV) biofeedback to treat moderate to severe depression. This was an open-label study in which 14 patients with different degrees of depression (13 f, 1 m) aged 30 years (18-47; median; range) and 12 healthy volunteers attended 6 sessions of HRV biofeedback over two weeks. Another 12 healthy subjects were observed under an active control condition. At follow up BDI was found significantly decreased (BDI 6; 2-20; median 25%-75% quartile) as compared to baseline conditions (BDI 22;15-29) in patients with depression. In addition, depressed patients had reduced anxiety, decreased heart rate and increased HRV after conduction of biofeedback (p < 0.05). By contrast, no changes were noted in healthy subjects receiving biofeedback nor in normal controls. In conclusion, HRV biofeedback appears to be a useful adjunct for the treatment of depression, associated with increases in HRV.
Article
We studied the correlation of changes in gain sensitivity of the baroreceptors and the development of resetting of the baroreceptors 2 and 6 days after the onset of hypertension produced by subdiaphragmatic aortic constriction in rats. Mean arterial pressure of anesthetized rats was maintained at approximately the same level as that of conscious rats, and baroreceptor function curves were studied on a beat-to-beat basis by computer. After 2 days of hypertension, the difference between the systolic pressure threshold and the control diastolic pressure was -13 +/- 2 mm Hg (125 +/- 3 versus 138 +/- 4 mm Hg). Individual values showed that in seven of nine hypertensive rats, the difference was less than 15 mm Hg, indicating complete resetting. After 6 days of hypertension, all rats exhibited complete resetting, when the systolic pressure threshold was similar to control diastolic pressure (143 +/- 4 versus 141 +/- 2 mm Hg), indicating that more than 2 days of hypertension is necessary for full displacement of the pressure thresholds when all hypertensive rats are considered. Slopes of the baroreceptor curves after 2 and 6 days of hypertension showed that baroreceptor gain was depressed by 25% and 34%, respectively. The difference was not statistically significant (1.07 +/- 0.054% versus 0.94 +/- 0.049% and 1.43 +/- 0.075% in controls). When changes in pressure were circumscribed to a more physiological range, a depression of 25% in response to +10 mm Hg and 37% in response to -10 mm Hg was observed.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
Sinoaortic denervation (SAD) is accompanied by an increase in blood pressure (BP) and a reduction in pulse-interval (PI) variance. Little is known, however, about the effect of SAD on the complex BP and PI variability pattern, which is identified by spectral analysis. In nine unanesthetized cats in which intra-arterial BP was monitored before and 7-10 days after SAD, spectral powers (estimated by fast Fourier transform) were calculated for the low frequency (LF, 0.025-0.07 Hz), midfrequency (MF, 0.07-0.14 Hz), and high frequency (HF, 0.14-0.60 Hz) band. The very low frequency (VLF) BP and PI components (VLF less than 0.025 Hz) were also estimated. SAD increased systolic BP variance and decreased PI variance. The reduction of PI variance was paralleled by significant and marked reductions in all PI powers including the VLF components. In contrast, the increase in systolic BP variance was accompanied by a marked increase in LF power, a decrease in MF power, and no change in HF power. The VLF BP components increased after SAD for frequencies between 0.025 and 0.0012 Hz, whereas a sudden marked reduction was observed below 0.0012 Hz. Similar results were obtained for diastolic BP powers. Thus the reduction in PI variance induced by SAD is paralleled by a reduction in all PI fluctuations identified by spectral analysis. This is not the case for the SAD-related increase in BP variance, which is accompanied by an increase, no change, or even a reduction in the different BP spectral components.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
Psychophysiological theories on the development of essential hypertension are reviewed and evaluated. Two interconnected theories that relate behavior to essential hypertension and account for individual differences in susceptibility to disease are the "hyperreactivity" theory and "the symptom specificity" theory. The "hyperreactivity" theory identifies individual differences in autonomic nervous system reactivity as the pathophysiological mechanism and the "symptom specificity" theory suggests that inflexible, stereotypical responding increases the risk to develop hypertension. Based on a literature review, these theories are examined. There exist both case/control and prospective studies on autonomic nervous system reactivity and the development of hypertension. It is concluded that a neurogenically mediated hyperreactivity to stress is a precursor and not an effect of hypertension. Tasks that call for active but not passive coping efforts are more efficient elicitors of reactivity differences between those at high and low risk to develop hypertension in case/control studies. In prospective studies, active tasks may also have a predictive advantage over passive with respect to blood pressure development. In the early phase of hypertension, an increased cardiovascular reactivity is accompanied by increased neuroendocrine activation. In the later phase, heightened reactivity is confined to the cardiovascular system. This does not prove but is consistent with the notion that transient episodes of increased cardiac output translate into essential hypertension by causing vascular hypertrophy. Case/control studies suggest that an increased "symptom specificity", with stereotypical responding across multiple stressors, is independent of cardiovascular reactivity and a precursor of hypertension. The literature lacks prospective studies on the clinical relevance of stereotypical responding. It is suggested that the presence of both hyperreactivity and symptom specificity in a single individual increases the risk to develop essential hypertension.
Article
Animal studies have demonstrated that activation of the baroreflex by increases in arterial pressure inhibits cardiovascular and ventilatory responses to activation of peripheral chemoreceptors (PC) with hypoxia. In this study, we examined the influences of baroreflex activation on the sympathetic response to stimulation of PC and central chemoreceptors in humans. PC were stimulated by hypoxia (10% O2/90% N2) (n = 6) and central chemoreceptors by hypercapnia (7% CO2/93% O2) (n = 6). Responses to a cold pressor stimulus were also obtained as an internal reflex control to determine the selectivity of the interactive influence of baroreflex activation. Baroreflex activation was achieved by raising mean blood pressure by greater than 10 mmHg with intravenous infusion of phenylephrine (PE). Sympathetic nerve activity (SNA) to muscle was recorded from a peroneal nerve (microneurography). During hypoxia alone, SNA increased from 255 +/- 92 to 354 +/- 107 U/min (P less than 0.05). During PE alone, mean blood pressure increased and SNA decreased to 87 +/- 45 U/min (P less than 0.05). With hypoxia during baroreflex activation with PE, SNA did not increase (50 +/- 23 U/min). During hypercapnia alone, SNA increased from 116 +/- 39 to 234 +/- 72 U/min (P less than 0.01). Hypercapnia during baroreflex activation with PE increased SNA from 32 +/- 25 U/min during PE alone to 61 +/- 26 U/min during hypercapnia and PE (P less than 0.05). Like hypercapnia (but unlike hypoxia) the cold pressor test also increased SNA during PE. We conclude that baroreflex activation selectively abolishes the SNA response to hypoxia but not to hypercapnia or the cold pressor test. The inhibitory interaction of the baroreflex and the peripheral chemoreflex may be explained by convergence of baroreceptor and peripheral chemoreceptor afferents on neurons in the medulla.
Article
For more than twenty-four hundred years, people were seen to behave in given ways because of what they were feeling or thinking, and feelings and thoughts were therefore the things to study. However, it has always been difficult to do very much with feelings and thoughts because of their inaccessibility to outside observers. Further, important distinctions are obscured when behavior is attributed to a state of mind. As more and more of the variables of which behavior is a function are identified and their role analysed, less remains to be explained in mentalistic ways. The operant side of behavior therapy is illustrated by considering a few characteristic problems. Discussion includes the analysis of contingencies outside and inside the clinic, and the relationship between behavioral health and medical health.
Article
Study of voluntary autoregulation of the heart rate (HR) by means of artificial biofeedback (BFB) using a display, has revealed the possibility of changing the HR voluntarily within a wide range of (from 50 to 140 beats per minute). Respective fluctuations occurred in the arterial pressure. A decrease in the HR and reactive alarm, increase in the self-assessment of physical state, activity, mood and work level occurred in result of the HR-BFB training.
Article
1. It is often assumed that the power in the low-(around 0.10 Hz) and high-frequency (around 0.25 Hz) bands obtained by power spectral analysis of cardiovascular variables reflects vagal and sympathetic tone respectively. An alternative model attributes the low-frequency band to a resonance in the control system that is produced by the inefficiently slow time constant of the reflex response to beat-to-beat changes in blood pressure effected by the sympathetic (with or without the parasympathetic) arm(s) of the baroreflex (De Boer model). 2. We have applied the De Boer model of circulatory variability to patients with varying baroreflex sensitivity and one normal subject, and have shown that the main differences in spectral power (for both low and high frequency) between and within subjects are caused by changes in the arterial baroreflex gain, particularly for vagal control of heart rate (R—R interval) and left ventricular stroke output. We have computed the power spectrum at rest and during neck suction (to stimulate carotid baroreceptors). We stimulated the baroreceptors at two frequencies (0.1 and 0.2 Hz), which were both distinct from the controlled respiration rate (0.25 Hz), in both normal subjects and heart failure patients with either sensitive or poor baroreflex control. 3. The data broadly confirm the De Boer model. The low-frequency (0.1 Hz) peak in either R—R or blood pressure variability) was spontaneously generated only if the baroreflex control of the autonomic outflow was relatively intact. With a large stimulus to the carotid baroreceptor it was possible to influence the low-frequency R—R but not low-frequency blood pressure variability. This implies that it is too simplistic to use power spectral analysis as a simple measure of autonomic balance its underlying modulation is more complex than generally believed. 4. It may be that power spectral analysis is more a sensitive indicator of baroreflex control, particularly of vagal control, than direct evidence of autonomic balance. of course, there is often a correlation between the gain of the reflex and the autonomic balance of vagus and sympathetic. These considerations may help our understanding of some conditions, such as exercise or heart failure, when the power spectral analysis method fails to identify increased sympathetic discharge; this failure may partly be explained by the decrease in baroreflex sensitivity which occurs in these two conditions.
Article
Blood pressure variability includes rhythmic and nonrhythmic fluctuations that, with the use of spectral analysis, appear as clear peaks or broadband power, respectively. This review offers a concise and critical description of the spectral methods most commonly used (fast Fourier transform versus autoregressive modeling, time-varying versus broadband spectral analysis) and an evaluation of their advantages and disadvantages. It also provides insight into the problems that still affect the physiological and clinical interpretations of data provided by spectral analysis of blood pressure and heart rate variability. In particular, the assessment of blood pressure and heart rate spectra aimed at providing indexes of autonomic cardiovascular modulation is discussed. Evidence is given that multivariate models--which allow evaluation of the interactions between changes in blood pressure, heart rate, and other biological signals (such as respiratory activity) in the time or frequency domains--offer a more comprehensive approach to the assessment of cardiovascular regulation than that represented by the separate analysis of fluctuations in blood pressure or heart rate only.
Article
1. We have tested the hypothesis that the non-respiratory, low-frequency (around 0.1 Hz) fluctuations of heart rate variability are generated by the baroreflexes, but with a delay caused by the slower response of the efferent sympathetic arm, (compared with the vagus), in 11 healthy subjects (mean age ± SD 27 ± 5 years). 2. In random order, at the onset of 20 s of apnoea starting at end expiration, we applied either 600 ms neck suction (−40 mmHg) to the carotid sinus region, or no stimulus (anticipation control), or a loud whistle (alerting control), every 60s, for 30 min. (i.e. 10 of each ‘stimulus’). We recorded neck pressure, blood pressure (Finapres), R-R interval (ECG), infra-red plethysmographic skin blood flow and respiration (impedance). By subtracting the alerting response from the neck suction response we obtained the responses caused purely by baroreceptor stimulation. 3. The initial reflex bradycardia and hypotension was followed by arteriolar vasoconstriction, presumably due to recompensation by the baroreflex, and then by a further reflex bradycardia—producing a decaying oscillation of the R-R interval about the control R-R. The period of this damped oscillation was 0.103 ± 0.024 Hz, similar to the frequency of the low-frequency peak obtained by power spectral analysis of heart rate variability (0.093 ± 0.016 Hz, not significant) at rest. These two values were significantly correlated in individual subjects (r = 0.715, P < 0.025). 4. These findings support the hypothesis that the low-frequency waves of heart rate variability can be generated from baroreceptor sensed blood pressure fluctuations.