[Quantitative assessment of arterial capacitance in human by noninvasive method]

The purpose of this study was to determine the magnitude of arterial capacitance in human by noninvasive method. In 60 patients (Age: 62.1 +/- 13.4 years) without cardiovascular disease first-pass radionuclide angiography was performed using a digital gamma camera to calculate cardiac output and stroke volume (SV). Systolic interval (ts), diastolic interval (td) and arterial blood pressure were measured using ECG, phonocardiography and sphygmomanometer. We assumed a simple model in which all capacitance (C) lumped into one site with a resistance (R) in parallel to the C. C was calculated by the following basic equations. (Formula; see text) arterial diastolic pressure, E: left ventricular external work. Our results showed: 1) Arterial capacitance ranged from 0.38 ml/mmHg to 2.10 ml/mmHg and more than 60% of stroke volume was pooled in the arterial capacitor during systole. 2) Arterial capacitance fell linearly with age (C = 2.37-0.02 x Age, r = -0.680, p less than 0.001). It is concluded that the capacitor played an important role in arterial circulation.