The Upstroke of the Tissue Perfusion Wave Comprises an Initial Slow Phase that Can Quantify the Severity of Arterial Stenosis; A Novel Technology for Monitoring Peripheral Artery Disease.

Background: A novel method for monitoring arterial stenosis by quantifying the tissue perfusion dynamics was developed. Arterial stenosis is associated with peripheral adaptive vasodilatation, which alters the transfer function of the arterial tree. Consequently, the initial phase of the perfusion wave is slower in the presence of arterial stenosis although the pressure wave velocity increases with arteriosclerosis.

Method: A clinical study was conducted at the department of vascular surgery in Hadassah Medical Center. The perfusion dynamics was derived form impedance plethysmography and was compared to ABI,TBI, Duplex-Ultrasound, and angiography. The signals were 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 was comprised of two phases, an initial slow-rise phase that was followed by a steeper rise. The slow phase duration (SPd) was 142±35 ms in extremities with above-knee (AK) arterial disease (n=13) while significantly shorter SPd of only 30±17 ms (P <0.001) was recorded in below-knee arterial stenoses (n=6). ABI and TBI could not differentiate between these two groups. In the AK extremities, the SPd significantly decreased to 63±52 ms after successful revascularization (P<0.001). Moreover, in AK cases with a satisfactory post-operative result (Duplex assessment), the SPd dramatically decreased from 136±17 ms before revascularization to 29±9 ms afterward (P<0.001, n=8).

Conclusion: The SPd is a novel index that successfully detects above-knee arterial stenosis and correlates with the postoperative outcomes. The technology may improve the surveillance of PAD patients.