Peripheral Artery Disease

Peripheral Artery Disease (PAD)

PAD, which is estimated to affect 8-12 million Americans (20% of adults over the age of 65), is a common manifestation of atherosclerosis. With disease prevalence increasing with age, the total number of affected Americans could increase to 16 million aged 65 and older and as much as 19 million overall by 2050.

Since PAD is directly correlated to an individual’s overall atherosclerotic burden, even asymptomatic PAD is significant due to the long-term impact of the disease (vessel stenosis and tissue ischemia) in other body regions, such as in the coronary arteries and carotid arteries.

While smoking and diabetes are independent and well-documented risk factors, PAD is a very common disease of aging (even in patients without additional risk factors, particularly for those over 70).

Yet despite its high prevalence and impact, PAD is often only diagnosed after symptoms appear, indicating advanced atherosclerotic disease.

At these stages, PAD may result in limb threatening ischemia causing severe claudication and leg muscle pain, and, left un-treated, can ultimately lead to limb amputation and mortality associated with infection from gangrenous ulcers.

While existing primary diagnostic techniques, such as the ankle/brachial index (ABI), can identify PAD, they do not correlate with exercise impairment and are technically limited in patients with medial artery calcification leading to technically limited or non-diagnostic outcome in approximately 10% of studies. Existing imaging techniques (angiography and arterial ultrasound) used to determine the degree of arterial stenosis are expensive, immobile, require a trained specialist and do not provide simultaneous assessment of blood flow and oxygenation within the large muscle microvasculature.

Therefore, there is an urgent need for a simple, cost-effective and non-invasive system for PAD diagnosis and monitoring. In serveral clinical studies involving PAD, VOIS sensitively detected the differences in hemodynamic parameters in patients with PAD compared with healthy subjects during exercise, indicating the utility of both oxygenation and blood flow in characterization of PAD pathology.