Detection of restenosis in peripheral arteries and differentiation between arteriosclerosis and focal stenosis.

Introduction: The AHA and ECS guidelines recommend measurement of Ankle Brachial Index (ABI) for assessing atherosclerosis severity. ABI is used for arterial stenosis detection, but it is affected by arteriosclerosis severity, especially in diabetics and elderly. Peripheral artery restenosis rate after revascularization is high and there is an unmet for early detection of progressing stenosis. We hypothesized that quantification of tissue limb perfusion dynamics (PD), instead of a single point of peak pressure, can improve patient surveillance and the diagnosis.

Methods: A Helsinki approved clinical trial was conducted to measure the PD signals from the calf of PAD patients. The PD signals were derived from the cardiac cycle modulations of the calf impedance plethysmography. We compared the PD signals that were measured shortly before and after the revascularization procedures.

Results: Sixteen patients with isolated above-knee stenoses were recruited. The PD upstroke consisted of two characteristic phases: the initial slow phase was followed by a fast vigorous rise. The slow phase duration was significantly prolonged in the presence of arterial stenosis, compared to contralateral legs without stenoses, and it was denoted as the ‘Perfusion Deficit Index` (PDI). The PDI significantly decreased after revascularization, from 124±59 ms to 63±46 ms (n=16, p<0.01), and furthermore in satisfactory post-operative duplex cases (from 118±62 ms to 38±20 ms, n=11, p<0.01). The `pulse transit time` that relates to arteriosclerosis did not change between measurements. One diabetic patient underwent two revascularizations, in 4/2019 and 11/2020. In both cases the PDI dropped after revascularizations (from 241 to 34 ms, from 124 to 33 ms, respectively). The increase in PDI between the interventions strongly supports the feasibility of early detection of restenosis.

Conclusions: The PD can be used for monitoring atherosclerosis severity. The PDI is a novel sensitive index for detecting arterial stenoses, even in the presence of arteriosclerosis.