Quantification of the Severity of Arterial Stenosis Based on the Changes in the Initial Perfusion Wave Dynamics; A Novel Technology for Monitoring Peripheral Artery Disease.

Background: Peripheral Artery Disease (PAD) is major cause of cardiovascular morbidity and mortality, with over 200 million people affected worldwide. Current modalities lack sensitivity especially in the elderly and diabetics, when used for screening the population, and for early detection of restenosis after revascularization. We have hypothesized that arterial stenosis is associated with adaptive arteriolar vasodilatation, which alters the perfusion dynamics and prolongs the initial phase of the perfusion upstroke, and that these changes can be utilized for detection and quantification of the arterial stenosis severity.

Methods: A clinical study was initiated at the department of vascular surgery in Hadassah Medical Center. We measure the lower leg perfusion with impedance plethysmography and compare it with other modalities used in the clinic and the gold standard angiography. The signals are acquired from the PAD patients before and after they undergo revascularization.

Results: Eighteen consenting patients were recruited (61±10 years old) and nineteen legs were treated. The perfusion upstroke encompasses 2 or 3 distinctive phases. An initial slow phase that is followed by a brisk upstroke and a final sallower augmentation in some patients. The slow phase duration (SPd) was 113±45 ms in extremities with above-knee (AK) arterial stenosis (n=17) while significantly shorter SPd of 26±0 ms was observed in limbs without AK stenoses (n=2) (P = 0.011). In the AK extremities, the SPd significantly decreased to 52±40 ms after successful revascularization (P<0.01). Moreover, in AK cases with a satisfactory post-operative result (Duplex assessment), the SPd dramatically decreased from 103±35 ms before revascularization to 35±18 ms afterward (P<0.01, n=12).

Conclusions: Analysis of the perfusion dynamic provides a gamut of precious indices. The SPd is a novel index that can detect and quantify the severity of arterial stenosis. The technology can significantly improve the surveillance of PAD patients.