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ABSTRACT: We used a self-comparison method and harmonic analysis to compare the blood pressure wave before and after the injection of antihypertensive drugs (atenolol, captopril, and losartan) in normotensive Wistar Kyoto rats. Systolic and diastolic blood pressures decreased significantly after the intraperitoneal injection of drugs. Atenolol significantly reduced all the harmonic proportions of the pulse wave, while captopril and losartan significantly increased the first and fourth harmonic proportions. These findings are the same as those reported for human subjects and confirm that harmonic analysis of the pressure pulse is a useful method to study the efficacy of antihypertensive drugs.
Clinical and Experimental Hypertension 01/2012; 34(1):74-8. · 1.07 Impact Factor
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ABSTRACT: Analyzing the beat-to-beat cardiovascular variability (e.g., heart-rate variability analysis) provides important information regarding circulatory autonomic control. The present study aimed to use laser Doppler flowmetry (LDF) and beat-to-beat analysis to elucidate changes in the microcirculatory blood flow (MBF) and variations (MBFV) therein induced by local heating stimulation.
For each experiment, we applied nonpainful local heating and recorded a 20-min heating effect, which was segmented into four measurements separated by 5 min as M1-M4. DCflux (average LDF flux) was calculated for each pulse, and the coefficient of variance of DCflux (DCCV) was then calculated to evaluate the beat-to-beat MBFV.
In the linear regression analysis of the M2-M4 data sequence, the slope between relative changes (compared with M1 values) in DCCV and DCflux, and those between the proceeding DCCV and the subsequent DCflux, were negative (R(2) > 0.40 for all; p < 0.05).
This is the first study to reveal a possible time-domain relationship between changes in MBF and MBFV parameters. Our results suggest that MBFV evaluated from the beat-to-beat LDF waveform is useful for monitoring the microcirculatory regulatory activities of arteriolar openings, and might therefore be particularly meaningful when evaluating treatment techniques or drugs aimed at improving microcirculatory perfusion.
Photomedicine and laser surgery 12/2010; 28(6):785-92. · 1.76 Impact Factor
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ABSTRACT: There were evidences that the blood pressure measured on the radial artery under some vasodilators treatments will overestimate than which measured on the central artery. Our previous studies infer that the harmonic proportion of the 4th harmonic (C4) of the peripheral pressure pulse waveform could be an index related to the peripheral vascular tone. In this study, we used a vasodilator drug, captopril to verify the relationship between C4 and vasoactive drug. Thirteen male Wistar Kyoto rats weighing 270 to 350 grams were studied. The blood pressure waveforms measured on the tail artery were averaged every 10 minutes and Fourier transformed into frequency domain. The data measured 20 minutes before captopril (0.83mg/1kg) injection was used as control. Four 10 minutes after-drug data sets were compared with the control. The diastolic (DBP) and systolic (SBP) blood pressures decreased rapidly after captopril injection. The mean pulse pressure A0 has the same decreasing trend but less conspicuously. The harmonic proportion of the 4th harmonic decreases at the beginning but then increases dramatically. These results suggest that C4 could be an index related to the peripheral vascular tone. We present a harmonic based pulse waveform analysis method to provide a peripheral pressure waveform index which may be used to estimate the cardiovascular risk.
Bioinformatics and Biomedical Engineering (iCBBE), 2010 4th International Conference on; 07/2010
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ABSTRACT: Healthcare issues arose from population aging. Meanwhile, electrocardiogram (ECG) is a powerful measurement tool. The first step of ECG is to detect QRS complexes. A state-of-the-art QRS detection algorithm was modified and implemented. By the dedicated architecture design, the novel ASIC is proposed with 2.21 μW power consumption and 0.68mm<sup>2</sup> core area. It is the smallest QRS detection ASIC so far in the world. In addition, the positive prediction of the ASIC is 99.36% based on the MIT/BIH arrhythmia database certification.
Circuits and Systems (ISCAS), Proceedings of 2010 IEEE International Symposium on; 07/2010
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International Symposium on Circuits and Systems (ISCAS 2010), May 30 - June 2, 2010, Paris, France; 01/2010
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International Symposium on Circuits and Systems (ISCAS 2010), May 30 - June 2, 2010, Paris, France; 01/2010
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ABSTRACT: The central elastic arteries and the peripheral muscular arteries are different in their responses to aging. Aorta stiffens
in much larger extent with age than peripheral arteries do. Peripheral blood pressure indices such as pulse pressure (PP)
or augmentation index (AI) were preferred as surrogates in assessing arterial stiffness for clinical convenience. AI and PP
both increase progressively with age.
In this study, we present a harmonic based pulse waveform analysis method which may give similar result about central pressure
as augmentation index. This method avoids the extra but necessary manipulations such as flow measuring, 4th derivative of
pressure wave in determining the inflection point, the second systolic peak for augmentation index calculating, all these
manipulations can introduce error. The non-invasive peripheral pulse waveforms copied from published reports for several ageing
studies were analyzed. The mean pulse height A0 and the harmonic proportion of the 1st harmonic C1 increased but the harmonic proportion of the 3rd harmonic C3 and the harmonic proportion of the 4th harmonic C4 decreased with ageing. Aging had no significant effect on the harmonic proportion of the 2nd harmonic C2. Among all these harmonic indices, A0, the mean pulse pressure increased dramatically since the 6th decade.
These results suggest that A0 is related to aorta stiffen or PP sensitive. The gradual increasing of C1 and gradual decreasing
of C3 and C4 by ageing suggest that C1, C3 and C4 could be similar to AI; it corresponds to the pressure pulse waveform affected
from ageing.
The harmonic indices could be clinically useful in noninvasive cardio risk assessing for the elderly patients.
12/2008: pages 183-185;
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Hsin Hsiu,,
Wei-Chen Hsu,,
Chia Liang Hsu,,
Shih-Min Huang,, Ming-Yie Jan,,
Wei-Kung Wang,,
Yuh-Ying Lin Wang,
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ABSTRACT: We aimed to characterize the frequency spectra of skin blood flow signals simultaneously recorded at Hoku, an important acupoint in oriental medicine, and two nearby nonacupoints to understand the underlying physiological mechanism of acupuncture points. ECG and laser Doppler flowmetry signals were measured simultaneously. A four-level Haar wavelet transform was applied to the measured 20-minute LDF signals, and periodic oscillations with five characteristic frequency peaks were obtained within the following frequency bands: 0.0095–0.021, 0.021–0.052, 0.052–0.145, 0.145–0.6, and 0.6–1.6 Hz (defined as FR1–FR5), respectively. The power in FR3 was significantly larger at Hoku than at the two nonacupoints. Spectral analysis of the flux signal revealed that one of the major microcirculatory differences between acupoints and nonacupoints was in the different myogenic responses of their vascular beds. This information may aid the development of a method to noninvasively study the microcirculatory characteristics of the acupoint.
Engineering in Medicine and Biology Society, 2008. EMBS 2008. 30th Annual International Conference of the IEEE; 09/2008
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ABSTRACT: We aimed to assess the effects of acupuncture by analyzing the alternating current (AC) component of skin blood-flow signals (around the heartbeat frequency) simultaneously recorded at the Hoku acupoint, which is an important acupoint in oriental medicine, and two nearby non-acupoints following acupuncture stimulation (AS). Laser Doppler flowmetry signals were measured in 28 experiments on nine volunteers. Each experiment involved the recording of a 20-min control-data sequence and two sets of effects data recorded 0-20 min and 50-70 min after the AS had been stopped. The direct current (DC) and AC components (DCflux and ACflux, respectively), pulse width (PW), and foot delay time (FDT) of the flux signal were calculated. The DCflux, ACflux, PW, and FDT were all significantly increased only at Hoku following AS. Regression analysis between the DCflux and ACflux revealed that the slope was largest (>1) at Hoku among the measurement sites. Our results indicated that both the DCflux and ACflux in the microcirculatory perfusion were increased by stimulation at the Hoku acupoint, with the change being greatest for the latter. Parameters calculated from the pulsatile flux waveform, such as the PW and FDT, could contribute to noninvasive evaluations of the sympathetic neural activities and of the improvement in perfusion following AS.
Lasers in Medical Science 09/2008; 24(4):553-60. · 2.00 Impact Factor
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ABSTRACT: Heart rate variability (HRV) is a measure of variations in the heart rate. Over the last 25 years, HRV analysis has became more and more popular as a non-invasive research and clinical tool for indirectly investigating both cardiac and autonomic nervous system (ANS) function in both health and disease area. How the musical rhythmic characteristics, tempo and complexity, affect the performance of HRV is studied in this work. By understanding the relationship between music and the function of ANS, we can improve our life and health by music - non-invasively and simply.
BioMedical Engineering and Informatics, 2008. BMEI 2008. International Conference on; 06/2008
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ABSTRACT: The objective of this study was to determine the conditions for optimizing measurements obtained with a noninvasive blood glucose monitor using the optical signal of pulsatile microcirculation (OSPM) in both prediabetic and diabetic subjects receiving medication.
Eighteen subjects (3 prediabetic, 15 diabetic) aged 61.8 [15.9] years (mean [S.D.]) were studied. OSPM was the pulsatile component (P) of the signal obtained and analyzed by a blood glucose monitor. The measurement was calibrated to the fingerstick meter for each subject for personal calibration. Data were obtained from all subjects using both meters.
A total of 179 data pairs were measured and analyzed. The validity of the position of the tested finger was assessed using the position criterion, which resulted in the removal of 38 data pairs. The criterion for the intensity of the P signal was satisfied by 141 data pairs, with nonconforming data (with a much lower P signal) mainly occurring below 26 degrees C. A total of 113 data points passed both criteria, and 100% of them fell within Zones A and B of the Clarke error grid. Data in Zones A and B exhibited a linear relationship (r=.81; slope=0.82; intercept=28.0) between noninvasive and fingerstick measurements.
Environmental temperature has the greatest influence on the capability of the OSPM technique to monitoring blood glucose concentration, which is subject dependent. The position of the tested finger is the second major factor, hence a carefully designed finger adaptor is essential.
Journal of diabetes and its complications 05/2008; 22(6):371-6. · 2.11 Impact Factor
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ABSTRACT: In response to harmonic forces generated by the heart, the arterial system executes strong coupled distributed oscillatory motions. These oscillations are described by a pressure-area wave equation, which is solvable subject to appropriate Sturm–Liouville boundary conditions. The response pressure can be represented as a sum of stationary waves which are the eigenmodes of the whole arterial system. Natural frequencies of the system are related to the eigenvalues and the phase velocity. Matching of these natural frequencies with heart rate or its harmonics is important in ventricular-arterial coupling. Transfer functions for the pressure can be constructed from the corresponding eigenfunctions.
Applied Physics Letters 04/2008; 92(15):153901-153901-3. · 3.84 Impact Factor
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ABSTRACT: Laser Doppler flowmetry (LDF) is a popular method for monitoring the microcirculation, but it does not provide absolute measurements on local area with small size microvessels. Instead, the mean flux response is generally compared between before and after stimulus. In this study, we proposed a new dimension for comparing the LDF signals. The flux rise time (FRT), a time index with absolute physical quantity, was extracted from noisy LDF signals using a pulsatile-based synchronized-averaging method. We investigated the changes of FRT and its relation to the microvascular resistance (MVR) under the selective effects of angiotensin II (Ang II) on the kidney and the plantar palm. Ang II was infused into anesthetized Wistar Kyoto rats via the femoral vein for 1 h. Using the heartbeat as a self-trigger, we calculated the FRT and MVR from the renal cortical flux, plantar palm flux, and abdominal aortic blood pressure recorded before, during, and after Ang II infusion. The control FRT values were similar in the two vascular beds. Ang II decreased the renal cortical flux but significantly increased the FRT and MVR of both beds. The effects on the renal FRT and renal MVR were selectively larger than those on the palm FRT and palm MVR. The results indicate that the changes of FRT and MVR are similarly physiologically linked with microvascular structures. As an MVR-related absolute physical quantity, the FRT could be developed as a monitoring tool in physiological, pathological, and pharmacological investigations.
Microvascular Research 04/2008; 75(2):211-6. · 2.83 Impact Factor
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ABSTRACT: The present study used laser Doppler flowmetry (LDF) to investigate the connection between skin microcirculatory flow and the length of the RR interval (LRR). Local heating was performed on healthy volunteers to further elucidate its effect on LDF index. ECG and LDF signals were measured in 102 trials on seven volunteers. Each experiment involved a 5 min control and a 5 min heating-effect sequence. Each laser Doppler flux pulse was categorized into four groups according to its LRR compared with the 5 min average LRR. Synchronized averaging analysis was applied to the four groups of pulses to obtain their averaged waveforms, from which four flux parameters were calculated. The ac component of the flux increased significantly with increasing LRR, and the differences therein between the groups with LRR more than 4% smaller and more than 4% larger than the average LRR increased from 15.8% during the control period to 23.9% during the heating period. Understanding of the different flux responses between the control and local-heating experiments may aid the development of a new index, which helps to avoid LDF's main drawback of providing only qualitative measurement.
Physiological Measurement 03/2008; 29(2):245-54. · 1.68 Impact Factor
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ABSTRACT: We aimed to characterize the frequency spectra of skin blood flow signals simultaneously recorded at Hoku, an important acupoint in oriental medicine, and two nearby nonacupoints to understand the underlying physiological mechanism of acupuncture points. ECG and laser Doppler flowmetry signals were measured simultaneously. A four-level Haar wavelet transform was applied to the measured 20-minute LDF signals, and periodic oscillations with five characteristic frequency peaks were obtained within the following frequency bands: 0.0095-0.021, 0.021-0.052, 0.052-0.145, 0.145-0.6, and 0.6-1.6 Hz (defined as FR1-FR5), respectively. The power in FR3 was significantly larger at Hoku than at the two nonacupoints. Spectral analysis of the flux signal revealed that one of the major microcirculatory differences between acupoints and nonacupoints was in the different myogenic responses of their vascular beds. This information may aid the development of a method to noninvasively study the microcirculatory characteristics of the acupoint.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2008; 2008:1084-6.
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ABSTRACT: Acupuncture points (acupoints) form part of the meridian system that constitutes the most fundamental concept in oriental medicine, but their physiological basis has not been clarified. In this study we employed laser Doppler flowmetry (LDF) to extract the microcirculatory characteristics of acupoints and their surrounding tissues, and we interpreted the results from the viewpoint of microcirculatory physiology. Three groups of measurements were performed focusing on the following two important acupoints in oriental medicine in healthy volunteers (n = 13 for group A and n = 9 for groups B and C, respectively): Hoh-Ku (Li4, on the hand) and Ching-Ku (B64, on the foot). The two groups of measurements around Hoh-Ku (Groups A and B) were so designed as to examine the effect of the direction of the nonacupoint away from the acupoint, whereas comparison between the Hoh-Ku and the Ching-Ku measurements was to verify whether the phenomenon was consistent in the upper and the lower extremities. We found that the mean LDF signals were significantly larger at the acupoints than in their surrounding tissues (all p < 0.05), which indicates a larger blood supply into the microvascular beds of acupoints. The results indicate that the physical properties of the vascular structure of acupoints may affect the perfusion resistance, and thereby modulate the microcirculatory perfusion in accordance with tissue needs. This finding facilitates the localization of acupoints, helps in identifying the connection between microcirculatory physiology and responses to acupoint stimulation, and introduces an objective research method for understanding the mechanisms that underlie oriental medicine.
Physiological Measurement 11/2007; 28(10):N77-86. · 1.68 Impact Factor
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ABSTRACT: Pulse parameters calculated from the LDF waveform based on time-domain synchronized averaging analysis were shown to be able to discriminate the difference in microvascular resistance, however its applicability depends seriously on the assumption of signal stationarity. In this study, our aim is to investigate the effect of pulse number, which may destroy the signal stationarity, on the pulse LDF parameters. The study presented here has established the criteria for pulse number to achieve the signal stationarity so that the microcirculatory discriminability of the pulse-based time-averaging analysis on LDF signal can be improved. The proposed quantitative method to verify the assumption of signal stationarity when utilizing time-averaging can also be applied to analysis of other bio-signals.
Engineering in Medicine and Biology Society, 2007. EMBS 2007. 29th Annual International Conference of the IEEE; 09/2007
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ABSTRACT: A general axial momentum equation for fluid inside a transverse vibrating elastic tube is derived here. In a system with high pressure and low elastic modulus, transverse motion of the wall contributes important nonlinear forces, and the longitudinal fluid wave which assumes that flow is governed by the Navier-Stokes equation cannot describe the pulse wave completely. By comparing the transverse elastic wave with the longitudinal fluid wave, we conclude that transverse wave is a significant wave mode in large arteries. The longitudinal stress force, commonly ignored in the literature, can be considered as a significant factor that influences the propagation of the arterial pulse.
Journal of Applied Physics 09/2007; 102(6):064702-064702-4. · 2.17 Impact Factor
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[show abstract]
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ABSTRACT: Pulse parameters calculated from the LDF waveform based on time-domain synchronized averaging analysis were shown to be able to discriminate the difference in microvascular resistance, however its applicability depends seriously on the assumption of signal stationarity. In this study, our aim is to investigate the effect of pulse number, which may destroy the signal stationarity, on the pulse LDF parameters. The study presented here has established the criteria for pulse number to achieve the signal stationarity so that the microcirculatory discriminability of the pulse-based time-averaging analysis on LDF signal can be improved. The proposed quantitative method to verify the assumption of signal stationarity when utilizing time-averaging can also be applied to analysis of other bio-signals.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 02/2007; 2007:982-4.
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ABSTRACT: Meridian system composed of acupoints is the most fundamental concept to build oriental medicine. In this study, we employ LDF measurement to compare the microcirculatory blood velocity of acupuncture point and its surrounding tissues. Measurements were performed around an important acupoint in oriental medicine, Hoh-Ku (Li4, on the hand), in healthy volunteers. The study presented has shown that the acupoints have significantly slower mean blood velocity than their surrounding tissues (p all < 0.005). This finding facilitates the detection of the position of acupuncture point and helps us to provide a possible connection between microcirculatory physiology and the underlying mechanism of acupoints.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2007; 2007:959-62.
