Analysis of a thermal method for assessing endothelial dysfunction.

The presence of atherosclerosis not only affects the normal functioning of the coronary blood vessels but also of the peripheral vasculature. Property measurements made in the peripheral vasculature hence do reflect the condition of the coronary blood vessels. The endothelial cells form the inner lining of the blood vessels, and are responsible for the release of nitric oxide (NO) in order to control the vascular tone. Under normal conditions the artery will dilate in response to increased blood flow, mediated by the release of NO. The hampering of this normal response, caused by certain cardiovascular diseases, is referred to as endothelial dysfunction (EDF). Occlusion of the arm using a standard blood pressure cuff for five minutes followed by sudden release of the occlusion is known to create a reactive hyperemia in a normally functioning vasculature. We propose to measure the EDF by attempting to create this reactive hyperemia in the arm and measuring the temperature response in the hand and forearm, using a computer-based data acquisition system. The rate of temperature fall during occlusion and the temperature rate of rise after release are combined to assess EDF. An engineering analysis of the instrument was performed. Initial studies on normal subjects have indicated that the rate of rise is significantly higher than the rate of fall of temperature.