Estimation of Arterial Compliance

Abstract

As has been demonstrated in several previous chapters, the Windkessel model of the arterial system, despite its simplicity and attendant limitations, continues to be extremely useful both for understanding vascular physiology and for investigating ventricular/vascular coupling. The important parameters of this model are the compliance and the peripheral resistance. Whereas calculation of total peripheral resistance is straightforward and estimates are easily obtainable in vivo, estimation of total arterial compliance (the increment in volume produced by an increment of pressure) is very difficult. Direct measurement of overall arterial compliance is complicated by the need to measure accurately total arterial blood volume, and has been accomplished only in experimental animals (Shoukas and Sagawa 1973). Therefore in most instances, estimates of compliance are made indirectly by assuming that the aortic diastolic pressure decays exponentially with a time constant that is the product of total arterial resistance and compliance (Bourgeois et al. 1974; Conroy 1969; Defares and Van der Waal 1969, 1973; Deswysen, Charlier, and Gevers 1980; Iriuchijima, Kumazawa, and Kawakami 1971; Levy, Birkui, and Saumont 1978; Levy et al. 1985; Messerli, Frohlich, and Nutura 1985; Randall, Van den Bos, and Westerhof 1984; Simon et al. 1979; Simon, Levenson, and Safar 1985; Ventura et al. 1984).