STTR: Non-Invasive Physiologic Evaluation of Peripheral Artery Disease Grant uri icon

abstract

  • Peripheral arterial disease (PAD) is a subset of peripheral vascular disease, which describes a spectrum of perfusion- and metabolic-related threats to the tissues of the lower extremities. PAD affects an estimated 8.5 million adults in the US and > 200 million adults worldwide. PAD is a manifestation of atherosclerosis in the lower limbs, is often asymptomatic, but results in inadequate oxygen supply to lower extremity musculature during walking. Risk factors for PAD include smoking, diabetes, older age, high blood pressure, and high cholesterol; in this way it is similar angiographically and etiologically to stable ischemic heart disease. The initial diagnostic test in symptomatic patients (i.e., classic claudication) with PAD is the Ankle-Brachial Index (ABI) test, performed by a nurse/technician under a physician?s supervision. Proper technique is involved, and the accuracy of results can be improved by repeated measures. Studies in symptomatic patients have shown that an ABI 200 million adults worldwide. PAD is a manifestation of atherosclerosis in the lower limbs, is often asymptomatic, but results in inadequate oxygen supply to lower extremity musculature during walking. Risk factors for PAD include smoking, diabetes, older age, high blood pressure, and high cholesterol; in this way it is similar angiographically and etiologically to stable ischemic heart disease. The initial diagnostic test in symptomatic patients (i.e., classic claudication) with PAD is the Ankle-Brachial Index (ABI) test, performed by a nurse/technician under a physician?s supervision. Proper technique is involved, and the accuracy of results can be improved by repeated measures. Studies in symptomatic patients have shown that an ABI 50% stenosis) PAD (McDermott Edit Ref #4). In diabetics, however, this sensitivity is reduced to 50% (Han). Among patients with an ABI 50% angiographic stenosis in 19-23% patients in whom the ABI was < .90 in only 4.5%. (Table 2 results). The July 10, 2018 issue of JAMA published the USPSTF recommendations for use of the ABI in PAD asymptomatic patients. In the accompanying literature review of ABI screening in asymptomatic patients, the sensitivity was low (15-20%), the specificity was high (95-99%). The positive predictive value was 83%, and the negative predictive value was 80-84%. Therefore, in contrast to the majority of existing international recommendations, the USPSTF did not recommend the use of ABI as a screening test for patients with age- or disease-related risk factors for PAD, or for cardiovascular disease more broadly. The objective of this Phase II STTR grant is to develop and test a novel technologic solution to begin eliminating some of the uncertainty around this ABI testing in asymptomatic patients with PAD, and more broadly in peripheral vascular disease. In parallel to stable ischemic heart disease and functional stenoses, these vascular insufficiency conditions are not fully characterizable based on angiographic anatomy alone. Rather, the condition of the surrounding tissues perfused by the atherosclerotic arterial supply, including disease co-morbidities that affect the tissue microvascularity (i.e., diabetes), and affect the perfusion (i.e., smoking) account for some of this ABI uncertainty. Our hypothesis is that ABI-type data and these tissue- and perfusion-related factors can be captured and integrated in real-time to augment standard ABI testing. The technology for this novel solution is Multi-spectral Physiologic Visualization (MSPV), a platform imaging technology developed by the SBC RFPi, Inc., Greenville, NC. The current Phase I STTR grant R4XHL133633-01A1 Research Strategy has directly and positively impacted the Research Strategy of this Phase II application. This Strategy specifies designing, engineering, building, testing and validating in a clinical study the MSPVO2-ABI platform for use in the vascular clinic setting to further assess PAD and peripheral vascular disease patients. This Strategy has three (3) Specific Aims: 1) Integration of MPSV perfusion, metaKG physiologic parameters, and SpO2 and [Hgb] measurement and quantification in real-time. Milestones: establish optical phantom model; with testing finalize technical, hardware requirements; finalize operational MATLAB software platform. Months 1 - 4 2) Design, engineer, build, testing, and validation of the 4 prototypes: ini
  • RFPi, Inc has developed a novel imaging technology called Multi-Spectral Physiologic Visualziation (MSPV). The first clinical device for open surgery was approved by the FDA in December, 2018. This device is being commercialized currently.

date/time interval

  • September 2019 - July 2022

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