The EndoPAT provides a non-invasive method to give researchers a glimpse into the endothelial lining of our arteries. This lining consists of endothelial cells which comprise the inner walls of the heart and blood vessels. Detection of endothelial damage has been shown to be the earliest observable signs of cardiovascular disease. Maintaining healthy endothelial function is crucial in the prevention of atherosclerosis, plaque buildup and arterial hardening. The EndoPAT has been successfully employed at Harvard Medical School, Johns Hopkins, the Mayo Clinic and Emory.

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There is great interest in examining arterial stiffness as a surrogate marker of atherosclerosis (Cohn et al., 2004).

Interestingly, the reactive hyperemia PAT index has been reported to correlate with brachial artery flow-mediated dilation in the arm and is inversely related to risk factors and the presence of coronary artery disease (Kuvin et al., 2003). The response also correlates with endothelial function in the coronary circulation (Bonettiet al., 2004). Finally, the response improves after enhanced external counter pulsation therapy, an intervention known to improve peripheral artery endothelia function (Bonetti et al., 2003)" As cited in McMackin & Vita (2005).

Comparison between normal endothelial function and abnormal endothelial function results from ENDO-PAT
 

Source: Kuvin JT, Patel AR, Sliney KA, Pandian NG, Sheffy J, Schnall RP, Karas RH, Udelson JE. Assessment of peripheral vascular endothelial function with finger arterial pulse wave amplitude. Am Heart J (2003); 146: 168–174.

Selected studies which have utilized the EndoPAT
 

Noninvasive Identification of Patients with Early Coronary Atherosclerosis by Assessment of Digital Reactive Hyperemia

Piero O. Bonetti, MD et al.
Journal of the American College of Cardiology Vol. 44, No. 11, 2004

This study investigated the value of reactive hyperemia peripheral arterial tonometry (RH-PAT) as a noninvasive tool to identify individuals with coronary microvascular endothelial dysfunction. Coronary endothelial dysfunction, a systemic disorder, represents an early stage of atherosclerosis Using RH-PAT, digital pulse volume changes during reactive hyperemia were assessed in 94patients without obstructive coronary artery disease and either normal (n =39) or abnormal (n =55) coronary microvascular endothelial function; Findings suggest digital hyperemic response, as measured by RH-PAT, is attenuated in patients with coronary microvascular endothelial dysfunction, suggesting a role for RH-PAT as a noninvasive test to identify patients with this disorder.

Vitamin D Status Is Associated with Arterial Stiffness and Vascular Dysfunction in Healthy Humans

Ibhar Al Mheid, MD et al.
Journal of the American College of Cardiology 2011

The primary objective of this study was to elucidate mechanisms underlying the link between vitamin D status and cardiovascular disease. Endothelial function was assessed as brachial artery flow mediated dilation, and microvascular junction was assessed as digital reactive hyperemia index. Carotid-femoral pulse wave velocity and radial tonometry-derived central augmentation index and subendocardial viability ratio were measured to assess arterial stiffness.Results suggest that Vitamin D insufficiency is associated with increased arterial stiffness and endothelial dysfunction in the conductance and resistance blood vessels in humans, irrespective of traditional risk burden. Our findings provide impetus for larger trials to assess the effects of vitamin D therapy in cardiovascular disease.

Effects of Therapeutic Lifestyle Changes on Peripheral Artery Tonometry in Patients with Abdominal Obesity

R. Ferre´ et al.
Nutrition, Metabolism & Cardiovascular Diseases (2010)

In this study, the authors' aimed to prospectively assess the effects of therapeutic lifestyle changes on endothelial function measured by PAT in increased cardio vascular risk patients with abdominal obesity 150 patients with abdominal obesity and moderate cardio vascular risk were randomized to groups receiving a one-year intervention of either conventional medical care or an intensive therapeutic lifestyle changes program. It was found that good adherence to a therapeutic lifestyle changes program reduces global cardio vascular risk and determines PAT ratio improvement.

Digital Assessment of Endothelial Function and Ischemic Heart Disease in Women

Yasushi Matsuzawa, MD et al.
American College of Cardiology Foundation 2010

Ischemic heart disease is a leading cause of mortality, and its pathogenesis is diverse in women. This study investigated the utility of digital reactive hyperemia peripheral arterial tonometry (RH-PAT) in predicting Ischemic heart disease, including obstructive coronary artery disease and nonobstructive coronary artery disease, in women.
RH-PAT indexes were significantly attenuated in women with Ischemic heart disease. These findings suggest the value of digital RH-PAT in identifying patients with Ischemic heart disease, especially nonobstructive coronary artery disease before angiography. RH-PAT is potentially useful for identifying high-risk women for Ischemic heart disease.