A new description of arterial function: the compliance-pressure loop.

Hypertension and atherosclerosis are associated with reduced arterial compliance, which is the principal component that reflects the dynamic behavior of the arterial system. Hence, change in arterial compliance has been used as a compass of arterial wall properties, as well as an effective parameter for assessing therapeutic treatment efficacy. The arterial compliance-blood pressure loop concept is introduced here for assessment of arterial function. Aortic pressure and flow were measured in experimental dogs during normal and acute hypertension. The compliance-pressure loops were constructed from pulsatile blood pressure waveforms and the corresponding compliances. The features of the loop are that, for any given heart beat, arterial compliance is seen to be maximal in early systole to facilitate ventricular ejection, compliance decreasing during the remainder of systole owing to increased blood pressure and reduced aortic flow, compliance in diastole increasing as pressure declines. The arteries are stiffer with reduced compliance in hypertension. Thus, the compliance-pressure loop can provide an effective characterization of the dynamic behavior of the arterial system in terms of pressure-flow relation and blood vessel properties.