A Novel Modality for Assessing the Severity of Atherosclerosis Disease

Patients with peripheral arterial disease (PAD) are at high risk of cardiovascular morbidity. Recent guidelines stress the importance of monitoring PAD in mitigating the risks of cardiac diseases and suggest to measure the Ankle-Brachial index (ABI) despite its limitations. We hypothesize that quantifying the peripheral perfusion dynamics is more accurate than ABI. We have developed a noninvasive system that continuously monitors extremity perfusion by miniature sensors and impedance electrodes. Perfusion dynamics was analyzed in the time and frequency domains and by wavelet correlations between various hemodynamic signals. Partial arterial occlusion was modeled by inflating a blood pressure cuff around the thigh. Inflating the cuff to 45 and 90 mmHg had no significant effects on the ABI or oxygen saturation. However, it yielded new pathognomonic indices, e.g. phase delays between hemodynamic signals, that were proportional to the degree of the occlusion. The method may differentiate between arterial and venous problems. Monitoring the perfusion dynamics outperforms the ABI and merits clinical studies in high risk patients.