Evaluation of endothelial function by peripheral arterial tonometry and relation with the nitric oxide pathway.

Endothelial dysfunction is an important component in the development of cardiovascular diseases. Endothelial function may be evaluated by peripheral arterial tonometry (PAT) which measures the vasodilator function in the microvasculature of the fingertip during reactive hyperaemia. The reactive hyperaemia index (RHI) is decreased in the presence of cardiovascular risk factors and thus far several studies have shown that PAT-RHI may provide reliable prediction of outcome. The technique is operator independent and easy to perform. Abnormalities measured by PAT follow the same trend as those measured by flow-mediated dilation in the brachial artery, but the two methods are not interchangeable. We have reviewed the recent literature in an effort to evaluate peripheral arterial tonometry as a method to assess the function of the endothelium and additionally suggest directions for future research. Special attention will be directed to the nitric oxide dependency of the reactive hyperaemia index obtained by peripheral arterial tonometry.