Figure 4

Illustration of the importance of various arterial mechanical properties in generating the aortic pressure waveform. With the measured instantaneous flow [Q(t)] as an input, a single resistance (R) model of the circulation (model 1) would generate a pressure waveform [P(t)] with morphology identical to that of the flow waveform, differing only in magnitude by a factor of R. When arterial compliance, represented by a capacitance element (C), is incorporated (model 2), the predicted pressure waveform begins to exhibit many of the morphological characteristics of its measured counterpart. If a third element representing characteristic impedance (Z) is introduced (model 3), the morphologies of the predicted and measured pressure waveforms become very similar [23].