Fig. 5: Animal application of the thrill sensor during rapid and continuous vascular access (VA) changes.

Schematic of vein-side stenosis (a) and artery-side stenosis (b) in Canine 1 induced by finger pressure. The thrill sensor (purple) and commercial digital stethoscope (blue) simultaneously monitor the vascular access (VA) thrill signal. The Doppler ultrasound image shows a 56%/57% flow reduction, and the thrill signal decreases continuously, demonstrating the sensor’s rapid response. c Time-domain thrill signals monitored by the thrill sensor (purple) and commercial digital stethoscope (blue), and Doppler ultrasound images during percutaneous transluminal angioplasty (PTA) surgery in Canine 2, including: occlusion (no blood flow detected), half revascularization (402.36 mL/min), and full revascularization (808.07 mL/min). d Histogram of thrill intensity variation calculated from the above cases of Canine 1 and Canine 2. The thrill intensity is significantly lower in the high-risk state than in the healthy state (critical flow rate = 500 mL/min, p = 0.0015, one-tailed Welch’s t-test). Data are presented as mean values ±  SD from n = 9 individual cardiac cycles in each flow rate state. e Time-domain thrill signals and the histogram of thrill intensity during the rapid process of severe stenosis (more than 80% stenosis within 8 s) in Canine 3. The thrill intensity decreases from 0.98 to 0.06 in vein-side stenosis (blue) and from 0.79 to 0.02 in artery-side stenosis (purple). f Comparison of thrill signals during severe stenosis in Canine 3. The pulse signal emerges at severe vein-side stenosis (blue), but not in severe artery-side stenosis (purple).