Reactive Hyperemia-Triggered Wrist Pulse Analysis for Early Monitoring of Young Men with High Atherosclerotic Risk

Abstract

The high prevalence of cardiovascular disease in young adults has raised significant concern regarding the early identification of risk factors to allow for timely intervention. This study aimed to identify young males at risk of atherosclerosis using a noninvasive instrument and an initial application percussion entropy analysis of the wrist pressure pulse (WPP). In total, 49 young males aged 18 to 28, without any known history of vascular disease, were recruited. Blood samples were obtained whereby a TC/HDL cutoff value of 4 was used to divide the young men into low-risk (Group 1, TC/HDL < 4, N = 32) and high-risk (Group 2, TC/HDL ≥ 4, N = 17) groups regarding atherosclerosis. The reactive hyperemia-triggered WPPs were measured using a modified air-pressure-sensing system (MAPSS). The dilation index (DI) of the endothelial function and percussion entropy index (PEI) of the heart rate variability (HRV) assessments, calculated using pragmatic signal-processing techniques, were compared between the two groups. The nonparametric Mann-Whitney U test showed that the DI and PEI of the two groups showed statistical differences (both p < 0.05). Not only could the MAPSS assess endothelial function and HRV in young males, but the results also showed that waist circumference and PEI may serve as indicators for the early identification of young males at risk of atherosclerosis.

Keywords: cardiovascular disease (CVD); dilation index (DI); endothelial dysfunction (ED); heart rate variability (HRV); reactive hyperemia; wrist pressure pulse (WPP).

Figure 1

Schematic illustration of the modified air pressure sensing system (MAPSS). The MAPSS hardware unit consists of an air pressure sensing unit, wrist/upper-arm air pump motor, and mixed signal processing unit. The analyzing software executes every six seconds after receiving the data from the mixed signal processing unit, which has a sampling rate of 500 Hz in the MAPSS software unit.

Figure 2

Wrist waveform extraction in the first 5 min (e.g., baseline). During the occlusion phase, the pressure cuff on the upper left arm was inflated to 200 mmHg to stop the blood flow for two minutes. For those two minutes, the wrist waveform was very small. When the arm pressure cuff deflated to 0 mmHg, the wrist waveform had a larger amplitude than baseline, and the peak-to-peak interval (PPI) time series changed under the effects of reactive hyperemia. The overall signal acquisition time was 16 min.