Pulse Arrival Time as an Alternative Biomarker to Detect Lower-Extremity Peripheral Artery Disease

1) The purpose of this study is to assess segmental pulse arrival time (PAT) as an alternative biomarker to detect lower-extremity peripheral artery disease (PAD), and to investigate the impacts of local skin heating and foot elevation. The secondary purpose will be to investigate the impacts of age on segmental PAT. The subject population will include any adults 19 years of age or older with or without PAD. Exclusion criteria include having an aortic aneurysm with or without previous intervention, previous revascularization surgeries of the arteries in the legs/aorta, walking impairments independent of PAD, gangrene or ulcers of the toes/feet, and currently pregnant or breastfeeding. 3) All aims of the present study will be completed with a single laboratory visit. Descriptive measurements will include height, weight, age, sex, body fat percentage, and self-reported medication and health history. Subjects will lie in the supine position for 20-min. After rest, either the ankle-brachial index (ABI) or PAT will be assessed. After 10-min of further rest, the other measurement will be performed. ABIs will be assessed according to current guidelines: blood pressures will be assessed in the dorsal pedis and tibialis posterior arteries of both legs and the brachial arteries of both arms using a blood pressure cuff and Doppler ultrasound. PAT will be simultaneously assessed in both arms and legs using an investigational device with a 3-lead electrocardiogram sensor and four photoplethysmography (PPG) sensors. A PPG sensor will be applied to a finger on each hand and both big toes. Signals will be collected for 15-min with finger and toe sensor temperatures at 30 C. Toe sensor temperature will then be elevated to 45 C for 15-min. Finally, toe sensor temperature will remain at 45 C, and the feet will be elevated 8-in with a soft cushion for 15-min. Blood pressure in the arm and legs will be assessed at the end of each stage. Thermal images of the fingers and toes will be assessed before using the investigational device and after each stage. Subjects will then participate in a 6-min walking test (6MWT) to objectively establish walking capacity. The 6MWT will be performed in accordance with current guidelines. Segmental PATs will be compared with ABI and 6-min walking time to determine if segmental PATs can predict lower-extremity PAD (ABI) and the associated walking impairment (6MWT). This study is expected to last ~2.5hrs. 4) There will be no follow-up.