Flexible sensors to measure intravascular shear stress coupled with rapid and irregular atrial pacing

Abstract

Atrial fibrillation (AF), the most common cardiac arrhythmia, is characterized by multiple rapid atrial depolarizations leading to rapid and irregular ventricular responses exceeding 100 beats per minute (bpm). The hemodynamic effects of AF on the vascular endothelium are poorly undefined. To simulate AF, we paced the left atrial appendage of New Zealand White (NZW) rabbits (n=4) at rapid irregular intervals. The pacing protocol was as follows: 1) baseline sinus rhythm at 121.8 ± 1.6 bpm, 2) regular pacing at 168.3±0.5 bpm, and 3) irregular pacing at 167.1 ± 57.4 bpm. Surface electrical cardiograms (ECG) were recorded for changes in atrial and ventricular rhythm while flexible MEMs sensors were simultaneously deployed to the aorta for real‐time changes in intravascular thermal profiles. AF pacing at 168±37 (from 120±5.4) bpm decreased cycle lengths by 28% (from 491.5±21.6 to 355.9±78.2 ms), shear stress by 28% (from 32.0±2.4 to 22.7±3.5 dyne/cm2), and slew rate by 17% (from 1275±80 to 1056±180 dyne/cm2•s). Systolic and diastolic pressures were also reduced by 7.22 ± 4.13 mmHg and 7.72 ± 6.05 mmHg, respectively (baseline: 99/75 mmHg; regular pacing: 92/75; irregular pacing: 92/67; n=4, P < 0.001). These findings provide new methodology to measure spatial and temporal variations in intravascular shear stress in response to rapid and irregular atrial pacing.