Assessment of Endothelial Function Using Arterial Pressure Signals

Abstract

Peripheral arterial tonometry (PAT) is a useful method to assess endothelial function. Analysis of pulse wave amplitude with PAT during reactive hyperemia can be used to study peripheral vascular endothelial function very well. We had injected a specific nitric oxide (NO) synthesize inhibitor intra-arterially into five adult male rats to verify the validation of our proposed photoplethysmograpy (PPG) system for endothelial function assessment. However, the reproducibility was not good for the system applied for measuring fingertip peripheral arteries. Therefore, an air-pressure sensing system with the high reproducibility was developed for peripheral vascular endothelial function assessment. This study showed that the vasodilatation index measured with air-pressure sensing system correlated very well with that measured using peripheral arterial tonometry. In addition, only few minutes are needed for conducting a self endothelial function assessment at home. And, early self-monitoring of cardiovascular dysfunction and arterial stiffness can be easily and effectively achieved.

Penile Arterial Waveform Analyzer for Assessing Penile Vascular Function in Young Adults

“…Arterial pulsations were detected by a piezoresistive sensor through which the pressure signals (mmHg) were converted into electrical analog signals (mV). 37 The analog signals thus obtained were filtered, amplified, and DC level-regulated before being converted into 12-bit digital signals using a mixed signal processing unit (MSP430F449, Texas Instruments, USA) with a sampling frequency of 260 Hz. The digital signals were then transferred to a laptop computer as 6-s data set through an RS-232 interface.…”

“…Recording continued for seven more minutes with the cuff pressure maintained at 80 mmHg to detect the elicited RH before deflation and removal of the penile cuff. 8,37 The entire course of measurement lasted for 15 min.…”

“…The choice of time periods for data analysis was based on previous reports on RH in the fingers. 8,37 Since very limited variation was noted in arterial waveforms before induction of RH, 1 min was chosen or data acquisition during baseline. On the other hand, penile arterial pulse signals were recorded a minute after cuff deflation for 1 min since it is the period showing the maximal RH-elicited fluctuation in arterial waveforms over the fingers.…”

“…On the other hand, penile arterial pulse signals were recorded a minute after cuff deflation for 1 min since it is the period showing the maximal RH-elicited fluctuation in arterial waveforms over the fingers. 8,37 To examine whether the period that we chose for penile arterial waveform recording also reflects maximal fluctuation during RH as in the fingers, 8,37 the penile arterial signals from three volunteers were analyzed and showed maximal fluctuation in RH-induced arterial pulse signals 1 min after cuff deflation (data not shown). Since EEMD involves time-consuming calculation that is prolonged with the amount of information being analyzed, totally 2 min of representative information were analyzed without losing conciseness and preciseness.…”

“…The development of a clinically easyto-operate and reliable investigative tool, therefore, is needed for the evaluation of penile vascular integrity to guide appropriate medical or surgical treatments. Based on the principle of forearm reactive hyperemia (RH) elicited by a release of nitric oxide after a brief period of ischemia, 8,37 previous studies have proposed the calculation of area under the arterial waveform from the wrist as an indicator of the degree of upper limb perfusion and endothelial functional integrity. 11,37 The current study attempted to extrapolate the application to the assessment of penile vascular function utilizing a new system of arterial pulse wave contour analysis, namely, Penile Arterial Waveform Analyzer (PAWA).…”