The four-element Windkessel model

In earlier studies the authors found that the three-element windkessel, although an almost perfect load for isolated heart studies, does not lead to correct estimates of the total arterial parameters such as the aortic characteristic impedance and total arterial compliance. To overcome this problem the authors add a fourth element, the total arterial inertance, to the three-element windkessel. The three- and four-element windkessels were tested against an extended model of the systemic circulation. The four-element windkessel described arterial pressure and flow most accurately and the estimated lumped parameters were typically within 10% of the actual values of the arterial system, The three- and four element windkessel model were also fit to in vivo human aortic pressure and flow waves. Again, the four-element windkessel fitted better and the estimated arterial parameter values were closer to values obtained with standard methods.