Fabio Leonelli

• Professor (Associate) at University of South Florida

Atrial flutter (AFL) is a macro-reentrant arrhythmia characterized, in a 12 lead ECG, by the continuous oscillation of the isoelectric line in at least one lead. In the typical form of AFL, the oscillation is most obvious in the inferior leads, due to a macro-reentrant circuit localized in the right atrium, with the cavo-tricuspid isthmus as a crit...

Isthmus-dependent flutter represents a defeated arrhythmia. Possibly one of the most outstanding successes in terms of understanding the mechanism behind it has led to an effective, relatively simple, and safe targeted therapy. Technology, fulfilling a number of the clinical electrophysiologist's dreams, has linked diagnosis and therapy in computer...

Aims: The aim of this study is to quantify healthcare resource utilization among non-responders to cardiac resynchronization therapy (CRT-NR) by heart failure (HF) events and influence of comorbidities. Methods and results: The ADVANCE CRT registry (2013-2015) prospectively identified responders/CRT-NRs 6 months post-implant using the clinical c...

In some cases, atrioventricular reentrant arrhythmias are sustained by accessory pathways with peculiar electrophysiologic properties related to their specific anatomy. Most of these fibers, which may be responsible for variants of ventricular preexcitation, show decremental conduction properties due to a nodelike aspect or a peculiar tortuous anat...

Although catheter ablation of accessory pathways is deemed highly safe and effective, peculiar location of these pathways might lead to complex and potentially hazardous procedures requiring ablation in anatomic regions such as para-Hisian area, coronary sinus, and epicardial surface. The electrophysiologist should know these possible scenarios to...

Despite extensive knowledge of the physiopathology of ventricular pre-excitation, management of asymptomatic patients with this condition remains controversial.

Ventricular preexcitation is a depolarization of the ventricles that occurs before the conventional sequence, and the electrocardiogram is the specific test for diagnosis. A Kent bundle is the paradigm of ventricular preexcitation, and it is associated with short PR, wide QRS and delta wave. This finding is not always very evident, as it can have d...

Over the last decades, the approach to the Wolff-Parkinson-White syndrome, as well as its treatment, has substantially changed, leading to improvement in the prognosis and quality of life of these patients. From the first diagnostic electrophysiologic studies to the most recent evaluations, important data on pathophysiologic and clinical aspects ha...

An accessory pathway (AP) could manifest its presence exclusively during an orthodromic supraventricular tachycardia or with preexcitation during sinus rhythm (SR). The manifestations of the presence of an AP depend on its ability to conduct antegradely from atrium (A) to ventricle (V), retrogradely (V to A), or both. AP retrograde conduction is ne...

An accessory pathway (AP) can be apparent during sinus rhythm if it depolarizes part of the ventricles ahead of the normal wave front from the conduction system. An AP can generate an anatomic circuit able to sustain a macroreentrant atrioventricular reentrant tachycardia. This arrhythmia can engage the normal conducting system in an antegrade dire...

The Atrio Ventricular Junction (AVJ) is a well-defined anatomical region of the heart the physiology of which, despite extensive and numerous observations, it is not fully understood. The aim of this review is to present an up to date summary of old and more recent findings on histology, cellular electrophysiology and intracellular connectivity of...

Background: "Nonresponse" to cardiac resynchronization therapy (CRT) is recognized, but definition(s) applied in practice, treatment(s), and their consequences are little known. Objectives: The authors sought to assess nonresponse in the prospective, international, ADVANCE CRT registry (Advance Cardiac Resynchronization Therapy Registry). Metho...

Abnormalities in cardiac rhythm are caused by disorders of impulse generation, conduction, or a combination of the 2, and may be life-threatening because of a reduction in cardiac output or myocardial oxygenation. Cardiac arrhythmias are commonly classified as tachycardias (supraventricular or ventricular)or bradycardias. Bradycardias are uncommon...

Classic ECG interpretation is based on identification of waveforms and deductive analysis of the electrical events the waveforms represent. The more in depth the understanding of electrophysiologic cellular interactions, the more precise the interpretation of ECG tracing. Surface ECG has limitations; yet, it is accurate in representing myocytes’ pa...

Implantable loop recorders allow prolonged and continuous single-lead electrocardiogram recording, with the pivotal addition of remote monitoring. They have significantly shortened time to electrocardiographic diagnosis and appropriate therapy of many bradyarrhythmias/tachyarrhythmias and proved helpful in arrhythmia burden definition, offering inv...

Electrocardiography (ECG) in all its forms, from 12-lead ECG to long-term monitoring, is considered, an old and increasingly irrelevant test in this high technology era. This article reviews the clinical utility of this tool and argues that the obsolescence is due to an increasing inability to read electrocardiographic tracings. The usual interpret...

Pacemakers, cardioverter/defibrillators, and implantable loop recorders with their continuously improved diagnostic capabilities offer detailed information that can help interpreting a cardiac arrhythmia in implanted patients. Nevertheless, in some cases, analysis of the electrical signals stored in the device memory may not be easy. An accurate kn...

Several arrhythmogenic substrates may generate narrow QRS complex tachycardia, frequently encountered in clinical practice. Some narrow QRS complex tachycardias, however, are sustained by an uncommon arrhythmogenic mechanism. Although rare, these forms should be taken into account in the differential diagnosis to avoid misdiagnosis and improper pat...

Electrocardiographic algorithms are particularly useful to differentiate, in the presence of a wide complex tachycardia, between supraventricular aberrancy and ventricular tachycardias (VT). There are numerous limitations to the sensitivity and specificity of these algorithms including the presence of accessory pathways, use of antiarrhythmic drugs...

The 12-lead standard electrocardiogram (ECG) is a 10 second recording of human myocytes electrical activity. Filters and oversampling are necessary in order to acquire a smooth signal without distortion. ECG recordings may display ongoing arrhythmias, and some leads may be helpful in formulating the diagnosis. Advanced modalities of baseline ECG re...

Electrocardiogram (ECG) analysis trying to understand the mechanisms of QRS widening is often problematic. During WCTs, identification of P waves and atrioventricular relationship is often difficult and increasingly so if the number of recording leads available for examination is limited. For this reason, it is necessary to use every information av...

Polymorphic wide QRS complex tachycardia is defined as a tachyarrhythmia showing variable and frequently alternating morphologies of the QRS complex with irregular R-R intervals. It may present with a specific and reproducible pattern including torsade de pointes and bidirectional ventricular tachycardia or with a nonspecific and very irregular pat...

When faced with an electrocardiographic recoding of a complex arrhythmia, we often use inflexible algorithms or try to recall patterns already seen, which is often insufficient to explain the mechanisms of difficult bradycardias and tachycardias. We propose an approach to these situations where, starting from basic observations, the behavior of the...

Sinus node dysfunction or atrioventricular blocks are the causes of bradycardias. Diagnosis and management begin with evaluation of patient's hemodynamic status and diagnosis of bradycardia's cause. This is followed by an in depth evaluation of pathophysiology of the arrhythmia, its severity, and likelihood of progression. Implementing emergent mea...

Current ECG imaging (ECGi) systems deploy a large number of ECG sensors so as to provide the high-resolution body surface potential mapping (BSPM). The availability of BSPM was shown to substantially improve the early detection of life-threatening heart disease. However, most of existing ECGi systems employ an approximately uniform distribution of...

Atrioventricular node reentrant tachycardia (AVNRT) is a supraventricular arrhythmia easily diagnosed by 12-lead electrocardiogram. What is far more challenging, is the understanding of the reentrant circuit in its typical and atypical presentations. The function of the atrioventricular node is still incomplete and this knowledge gap is reflected i...

The sick sinus syndrome includes symptoms and signs related to sinus node dysfunction. This can be caused by intrinsic abnormal impulse formation and/or propagation from the sinus node or, in some cases, by extrinsic reversible causes. Careful evaluation of symptoms and of the electrocardiogram is of crucial importance, because diagnosis is mainly...

The common arrhythmia atrial fibrillation (AF) is incompletely understood. The mechanism of initiation and the perpetuation of AF remain speculative. This article summarizes current knowledge of the complex relationship between arrhythmias triggering AF and their long-term effects on atrial tissue, leading to perpetuation of tachycardia. It focuses...

This article describes the different anatomic structures involved in normal atrioventricular conduction and their pathologic states. It defines their effects on the electrocardiogram, and describes how to localize the level and evaluate the severity of conduction disease by electrocardiographic analysis. It illustrates the relevance of intracavitar...

From the atrioventricular node, electrical activation is propagated to both ventricles by a system of specialized conducting fibers, His Purkinje System (HPS), guaranteeing a fast, synchronous depolarization of both ventricles. From the predivisional common stem, a right and left branch separate, subdividing further in a fairly predictable fashion....

Atrial flutter, atrial tachycardias, and atrial fibrillation are the main sustained atrial tachycardias. Reentry, increased automaticity, and triggered activity are atrial arrhythmia's main mechanisms. Atrial flutter is the clinical and theoretical model of reentry. Its classification is based on the atrial chamber involved and the arrhythmia's ana...

The sinus node is the primary cardiac pacemaker from which the wavefront of activation proceeds through bundles of atrial fibers to the atrioventricular node. Left atrial activation proceeds along the Bachmann bundle and lower right atrium, determining P-wave morphology. Electrocardiogram reveals ectopic or retrograde atrial activation, wandering p...

QRS morphology is commonly used in the electrocardiographic diagnosis of ventricular depolarization such as left bundle branch block (LBBB) and ventricular septal infarction. We investigated whether pattern matching of QRS loops in the 3-dimensional vectorcardiogram (VCG) will improve the grouping of patients whose space-time electrical activity ak...

Cardiac electrical activities are varying in both space and time. Human heart consists of a fractal network of muscle cells, Purkinje fibers, arteries and veins. Whole-heart modeling of electrical wave conduction and propagation involves a greater level of complexity. Our previous work developed a computer model of the anatomically realistic heart...

Rapid advancements of sensing and mobile technology provide an unprecedented opportunity to empower smart and connected healthcare. Realizing the full potential of connected care depends, however, to a great extent on the capability of data analytics. Our previous study proposed a next-generation mobile health system, namely, the Internet of Heart...

Nonlinear dynamics arise whenever multifarious entities of a system cooperate, compete, or interfere. For example, cardiovascular system involves a great level of complexity. Multilead electrocardiogram (ECG) signals are generated through orchestrated depolarization and repolarization of cells and manifest significant nonlinear dynamics. Nonlinear...

In this chapter, we explore the use of data mining techniques to analyze patient-doctor communication and identify patterns in the communication that may be associated with patient's satisfaction. This is crucial in improving shared medical decision making, which allows doctors and patients to make effective decisions together. We explore clusterin...

Nonlinear dynamics arise whenever multifarious entities of a system cooperate, compete, or interfere. For example, cardiovascular system involves a great level of complexity. Multi-lead electrocardiogram (ECG) signals are generated through orchestrated depolarization and repolarization of cells and manifest significant nonlinear dynamics. Nonlinear...

Internet of Things (IoT) provides an unprecedented opportunity to realize smart automated systems such as smart manufacturing, smart city and smart home in the past few years. Pervasive sensing and mobile technology deployed in large-scale IoT systems lead to the accumulation of big data. In particular, wearable biosensing accelerates human-centere...

In clinical practice, Atrial Fibrillation (AF) is the most common and critical cardiac arrhythmia encountered. The treatment that can ensure permanent AF removal is catheter ablation, where cardiologists destroy the affected cardiac muscle cells with RF or Laser. In this procedure it is necessary to know exactly from which part of the heart AF trig...

Persistent Left Superior Vena Cava (PLSVC) has an estimated incidence of 0.2-0.8% in the general population and 3-10% in patients with known congenital heart disease [1]. A rare anatomic variation of LSVC occurs in up to 0.13% of otherwise normal individuals where both brachiocephalic venous systems drain into a persistent LSVC [1]. We describe a p...

Atrial Fibrillation, a common arrhythmia accompanied by an increased morbidity and mortality remains difficult to treat either with medications or invasive procedures. Targeted destruction of atrial fibrillation triggers offers the best hope for permanent resolution of the arrhythmia. In this work, identification of atrial triggers is based on the...

Cardiotoxicity of aggressive chemotherapeutic regimens includes cardiomyopathy and arrhythmias. Although cardiomyopathy is a well-recognized entity, arrhythmias are poorly studied. Certain chemotherapeutic regimes are associated with supraventricular arrhythmias, particularly atrial fibrillation. We retrospectively reviewed the data on patients who...

Management of atrial fibrillation, by far the most common sustained arrhythmia seen in clinical practice, is undergoing a profound reshaping, with a better definition of the role of different therapeutic strategies and an increasing impetus directed toward nonpharmacologic approaches for maintenance of sinus rhythm. Medical management using a prima...

This study is to quantify time-varying dominant frequencies in electrocardiogram (ECG) during the ventricular fibrillation (VF). Orthogonal ECG (sagittal, x; transverse, y; and longitudinal, z) and the transvenous two-leads defibrillation systems were set in 19 dogs. Time-frequency analysis was used to assess changes in the dominant frequency withi...

Marked first-degree AV block (PR> or =0.30 s) can produce a clinical condition similar to that of the pacemaker syndrome. Clinical evaluation often requires a treadmill stress test because patients are more likely to become symptomatic with mild or moderate exercise when the PR interval cannot adapt appropriately. Uncontrolled studies have shown th...

The objective of this study is to evaluate the correlation between the absolute ventricular fibrillation voltage (AVFV) computed from electrocardiogram (ECG) and the outcome of defibrillation shocks. Orthogonal ECG (sagittal, x; transverse, y; and longitudinal, z) was recorded from 11 dogs during 10 seconds of electrically induced ventricular fibri...

PATWARDHAN, A., et al.: Correlation Between Defibrillation Shock Outcome and Coherence in Elec-trocardiograms. Cycle periods in ECG during VF are correlated with periods of reentrant activation. The ECGs recorded from different locations on the thorax were contributed to from electrical activations within the heart in approximately inverse proporti...

Catheter ablation of the cavo-tricuspid isthmus is rapidly becoming the first line of treatment in the management of atrial flutter. The standard procedure is usually performed under fluoroscopy guidance and relays on multisite endocardial recordings to assess the completeness of the isthmus conduction block. Despite the high rate of success there...

We conducted this study to assess long-term results of three-dimensional (3-D) mapping-guided radiofrequency ablation (RFA) of inappropriate sinus tachycardia (IST). Change in activation after the administration of esmolol was also assessed and compared to the shift documented with successful sinus node (SN) modification. The long-term results afte...

Incisional atrial reentrant tachycardias are macroreentrant arrhythmias in which surgical scars or prosthetic material constitute one of the constraining barriers of the circuit. Accurate reconstruction based on fluoroscopy-guided endocardial mapping of the reentrant circuit is often incomplete and time consuming explaining, at least in part, the m...

The autonomic nervous system drives variability in heart rate, vascular tone, cardiac ejection, and arterial pressure, but gender differences in autonomic regulation of the latter three parameters are not well documented. In addition to mean values, we used spectral analysis to calculate variability in arterial pressure, heart rate (R-R interval, R...

Healthy young people may become syncopal during standing, head up tilt (HUT) or lower body negative pressure (LBNP). To evaluate why this happens we measured hormonal indices of autonomic activity along with arterial pressure (AP), heart rate (HR), stroke volume (SV), cardiac output (CO), total peripheral resistance (TPR) and measures of plasma vol...

Cycle periods in ECG during VF are correlated with periods of reentrant activation. The ECGs recorded from different locations on the thorax were contributed to from electrical activations within the heart in approximately inverse proportion of their distance from the recording sites. Similarity in cycle periods between ECGs recorded from two locat...

Periods of reentrant activation and effective refractory periods are correlated with dominant frequency or reciprocal of cycle periods during ventricular fibrillation (VF). In the present study, we used an analysis technique based on Wigner transforms to quantify time-varying dominant frequencies in electrocardiograms (ECGs) during VF. We estimated...

Despite the high success rate of radiofrequency (RF) ablation, pharmacologic therapy is still considered the standard initial therapeutic approach for atrial flutter. We prospectively compared the outcome at follow-up of patients with atrial flutter randomly assigned to drug therapy or RF ablation. Patients with at least two episodes of symptomatic...

Mapping and ablation of premature atrial contractions were performed in 48 patients with drug refractory persistent or chronic atrial fibrillation. At follow-up, 36 patients were arrhythmia free while continuing to take previously ineffective antiarrhythmic drugs. Thus, ablation of premature atrial contractions in combination with antiarrhythmic me...

In a series of 35 consecutive patients, the presence of a permanent pacemaker appears to be a strong risk factor for developing superior vena cava syndrome after radiofrequency modification of the sinus node. Treatment of this complication with balloon venoplasty is as effective as surgical repair.

We report the long-term follow-up of a right side only catheter ablation approach for paroxysmal AF. Eighteen patients with AF refractory to drugs entered the study. Ablation was attempted in the right atrium only by creating linear lesions based on a specific design including from two to four linear lesions. Induction of AF was attempted before ab...

In the present study we quantified changes in dominant frequency, which is reciprocal of activation interval or cycle period, during ventricular fibrillation (VF). We used a Smoothed Pseudo Wigner Distribution (SPWD) to estimate time-frequency representations of epicardial electrograms recorded in swines. We used a sock with 64 electrodes spaced eq...

Recent evidence suggests that the dominant frequencies during ventricular fibrillation (VF) may be used as indicators of dispersion in repolarization and in activation patterns. In the present study, we quantified dominant frequencies from multiple epicardial electrodes to investigate if there are differences in the averaged frequencies within the...

OBJECTIVES This study examined differences in mechanisms of head-up tilt (HUT)-induced syncope between normal controls and patients with neurocardiogenic syncope.BACKGROUNDA variable proportion of normal individuals experience syncope during HUT. Differences in the mechanisms of HUT-mediated syncope between this group and patients with neurocardiog...

OBJECTIVES This study examined differences in mechanisms of head-up tilt (HUT)-induced syncope between normal controls and patients with neurocardiogenic syncope.BACKGROUNDA variable proportion of normal individuals experience syncope during HUT. Differences in the mechanisms of HUT-mediated syncope between this group and patients with neurocardiog...

We assess whether AV node ablation and pacemaker implantation after discontinuation of effective rate-control medical therapy for chronic atrial fibrillation had a positive impact on quality of life and exercise performance. To assess the possibility of a placebo effect following pacemaker implantation, the study included three groups of patients....

We repeated direct-current cardioversion of atrial fibrillation after ibutilide injection in patients who failed conventional cardioversion. Eleven of 12 patients (92%) had successful cardioversion and avoided the need for internal cardioversion.

The optimal electrode configuration for endocardial defibrillation is still a matter of debate. Current data suggests that a two pathway configuration using the right ventricle (RV) as cathode and a common anode constituted by a superior vena cava (SVC) and a pectoral can (C) is the most effective combination. This may be related to the more unifor...

Radiofrequency (RF) ablation of the tricuspid valve-inferior vena cava isthmus is now the first line of treatment in the management of typical atrial flutter. Successful ablation is associated with conduction block in this region, although the histopathologic changes following this procedure have never been reported. We describe the pathologic chan...

We investigated whether the degree of phase coupling among orthogonal electrocardiograms during ventricular fibrillation (VF) was correlated with defibrillation shock outcome. We used cross bispectrum to estimate the degree of phase coupling. In dogs, VF was electrically induced and terminated with a defibrillation shock with a 50% probability of s...

In the present study the authors quantified the degree of changes in the dominant frequencies during ventricular fibrillation using Wigner transforms. They used auto-bispectra to quantify phase coupling between the different dominant rhythms. Results of 427 trials in 10 dogs showed substantial frequency modulation within ECGs, up to ±14% from the m...

The authors hypothesized that spatio-temporal anisotropy may lead to changes in critical interval and time-coherence that are observed experimentally. To test their hypothesis they performed numerical simulations. Using an S1-S2 protocol rotors were induced in the left and right half of a 128×128 matrix of cells using a Fitzhugh-Nagumo model. Midwa...

Radiofrequency (RF) catheter modification of the sinus node appears to be a promising therapeutic modality for the treatment of inappropriate sinus tachycardia. Modification, as opposed to total obliteration, of the atrial pacemaker requires precise localization of the sinus node. This has been successfully achieved with a multicatheter approach gu...

Previous work had demonstrated a reduced specificity associated with head-up tilt protocols using high-dose isoproterenol in patients between 20 and 50 years of age. We evaluated the specificity of head-up tilt testing using different isoproterenol infusion doses and administration of nitroglycerin in patients aged >60 years. In addition, whether t...

We used Hilbert transforms to re-evaluate the previously reported correlation between defibrillation shock outcome and absolute ventricular fibrillation voltage (AVFV). Previously in the literature, single values of AVFV acquired just prior to shock delivery were used to show a correlation between AVFV and shock outcome. In subsequent studies, a mo...

We report our experience with mapping and ablation of right and left atrial tachycardia using a 3-dimensional nonfluoroscopic mapping system. Twenty-nine ectopic atrial tachycardias were successfully ablated. This novel mapping system has the potential to increase a successful cure of this arrhythmia by catheter ablation.

One mechanism of neurally mediated syncope during Head-up Tilt (HUT) is stimulation of left ventricular (LV) mechanoreceptors. The purpose of this study was to compare cardiovascular responses and catecholamine levels in 8 normal controls (N) and 20 patients with a syncopal (positive) response to HUT (P). HUT was performed at 80° for 30 minutes. He...

Nine young, healthy men (171±4.4 cm, 77.4±3.9 kg, 23.1±1.8 yr) were studied before and after 48 hours of 6° head down bed rest (HDBR). Arterial pressure (AP, Finapress), heart rate (HR, BoMed), stroke volume (SV, BoMed), cardiac output (CO, BoMed), radial artery flow (RF, BoMed), skin perfusion of palm and calf (SP1, SP2, Perimed) and peripheral va...

Nine young healthy men (171.2 ± 4.4 cm, 77.4 ± 3.9 kg, 23.1 ± 18 yr) were studied before, during, and at the end of 48 hours of 6° head down bed rest (HDBR). Arterial pressure (Finapres), heart rate (BoMed), stroke volume (BoMed), cardiac output (BoMed), radial artery flow (Parks), skin perfusion of palm and calf (Perimed) and peripheral vascular r...

We sought to determine whether electromagnetic interference with cardiac pacemakers occurs during the operation of contemporary electrical dental equipment. Fourteen electrical dental devices were tested in vitro for their ability to interfere with the function of two Medtronics cardiac pacemakers (one a dual-chamber, bipolar Thera 7942 pacemaker,...

This study evaluates the immediate effects of the endocardial electrical shocks delivered by a transvenous defibrillation system on left ventricular (LV) function in a pig model. A triple-lead system consisting of two endocardial electrodes, in the right ventricular apex and the junction of superior cava-right atrium, and a custom-made defibrillati...

This study was designed to demonstrate the effects of varying the atrioventricular delay (AVD) on ventricular diastolic filling dynamics and the resultant stroke volume in patients with complete heart block and normal cardiac function. We studied 7 patients with normal cardiac function in whom a dual chamber pacemaker had been implanted because of...

Intraperitoneal migration of an abdominally implanted cardioverter defibrillator is a complication not yet fully described. In a consecutive series of 195 patients, migration occurred between 1 and 20 months in 5 (8%) of the 63 patients in whom a subrectus abdomini placement of the generator was chosen. It was unrelated to the patients' clinical ch...

Recent reports from experimental and modeling studies of epicardial electrical activation during VF suggest that non-stationarity of the core of activation modulates the frequency of surface ECG through the Doppler phenomenon. Our objective in the present study was to use time-frequency analysis nalysis to localize the frequency of the dominant rhy...

Short-time Fourier transform (STFT) of RR-interval was used to investigate the autonomic responses of 20 subjects (10) each men and women) to supine control and to 30 minutes of 80° Head-up tilt (HUT). Subjects were either normal volunteers or patients who had experienced prior episodes of syncope. Subjects were classified as either syncopal or non...

Hematocrit (HCT) values for 15 volunteers (vol) and 18 patients (pts) were determined before and during 30 min of 70° head up tilt (HUT). Blood samples were taken from the antecubital vein at the end of 20 min of supine control and at 8, 18, and 28 min of HUT. Nine of the volunteers and 11 of the patients had syncopal symptoms prior to the end of t...

Volumetric changes in the cardiovascular system associated with lower body negative pressure(LBNP) at -35mmHg were measured by ECG-triggered MRI at selected sites in 22 healthy volunteers (10 male, 12 female). Significance differences were accepted at p<. 05. MRI measures of left ventricular end diastolic volume (LVEDV) in the axial plane showed a...

Data were combined from two studies in which 20 women (165 ± 3 cm, 68 ± 3 kg, 25 ± 1 yr, follicular phase) were exposed to 30 lower body negative pressure (LBNP) sesssions. Ten women were tested twice (-1 month apart) using -40 mmHg LBNP and another group of ten women were tested once using 20 min of -35 mmHg LBNP. Continuous measurements of arteri...

To study the long-term evolution, determinants, and clinical relevance of the conduction abnormalities after orthotopic heart transplantation, 87 patients, followed for a mean of 105 +/- 72 weeks, were divided into 3 groups according to the characteristics of their electrocardiograms compared with their initial electrocardiogram recorded at study e...

Arterial pressure (AP), heart rate (HR) anil stroke volume (SV) were measured and peripheral resistance (TPR) was calculated for 10 each normotensive men (17511 cm, 74±2 kg, 25+1 yr) and women (162±2 cm, 66+2.5 kg, 25±1 yr). Each subject was studied at supine rest, before and after acute beta blockade (IV propranolol, 0.2 mg/kg). Mean values and sp...

Ten each normotensive men (175±1 cm, 74±2 kg, 25±1 yr) and women (162±2 cm, 66±2.5 kg, 25±1 yr) were studied at supine rest, before and after acute autonomie blockade (IV propranolol, .2 mg/kg; atropine, .04 me/kg). Mean values of hormonal indices were measured: norcpinephrine (NE), epinephrine (E), plasma renin activity (PRA), and pancreatic polyp...