Wrist ballistocardiography and invasively recorded blood pressure in healthy volunteers during reclining bike exercise

Abstract

Objective: Ballistocardiogram (BCG) features are of interest in wearable cardiovascular monitoring of cardiac performance. We assess feasibility of wrist acceleration BCG during exercise for estimating pulse transit time (PTT), enabling broader cardiovascular response studies during acute exercise and improved monitoring in individuals at risk for cardiovascular disease (CVD). We also examine the relationship between PTT, blood pressure (BP), and stroke volume (SV) during exercise and posture interventions.Methods: 25 participants underwent a bike exercise protocol with four incremental workloads (0 W, 50 W, 100 W, and 150 W) in supine and semirecumbent postures. BCG, invasive radial artery BP, tonometry, photoplethysmography (PPG) and echocardiography were recorded. Ensemble averages of BCG signals determined aortic valve opening (AVO) timings, combined with peripheral pulse wave arrival times to calculate PTT. We tested for significance using Wilcoxon signed-rank test.Results: BCG was successfully recorded at the wrist during exercise. PTT exhibited a moderate negative correlation with systolic BP (ρSup = −0.65, ρSR = −0.57, ρAll = −0.54). PTT differences between supine and semirecumbent conditions were significant at 0 W and 50 W (p < 0.001), less at 100 W (p = 0.0135) and 150 W (p = 0.031). SBP and DBP were lower in semirecumbent posture (p < 0.01), while HR was slightly higher. Echocardiography confirmed association of BCG features with AVO and indicated a positive relationship between BCG amplitude and SV (ρ = 0.74).Significance: Wrist BCG may allow convenient PTT and possibly SV tracking during exercise, enabling studies of cardiovascular response to acute exercise and convenient monitoring of cardiovascular performance.

Cardiac output estimation using ballistocardiography: a feasibility study in healthy subjects

“…Thus, waveform features extracted from BCG sensors located on a bathroom scale 22,23 , on the seat of a chair 24 , and on body surface 25 have been reported to track changes in CO. The amplitude of the BCG waveform recorded by sensors located on a force plate 26 and on the wrist 27 has been found to be positively correlated with CO. BCG acquired by sensors installed on home bathroom scale 28 , on a static-charge-sensitive bed 29 , and on the wrist 27 has even been suggested as a surrogate measure of heart contractility. Nevertheless, none of the previous studies were conducted in a prehospital emergency setting and did not propose a method for CO estimation.…”