Development of a hydraulic model of the human systemic circulation

Physical and numeric models of the human circulation are constructed for a number of objectives, including studies and training in physiologic control , interpretation of clinical observations, and testing of prosthetic cardio vascular devices. For many of these purposes it is important to quantitativ ely validate the dynamic response of the models in terms of the input imped ance (Z = oscillatory pressure/oscillatory flow). To address this need, the authors developed an improved physical model. Using a computer study, the authors first identified the configuration of lumped parameter elements in a model of the systemic circulation; the result was a good match with human aortic input impedance with a minimum number of elements. Design, construc tion, and testing of a hydraulic model analogous to the computer model foll owed! Numeric results showed that a three element model with two resistors and one compliance produced reasonable matching without undue complication. The subsequent analogous hydraulic model included adjustable resistors inc orporating a sliding plate to vary the flow area through a porous material and an adjustable compliance consisting of a variable-volume air chamber. T he response of the hydraulic model compared favorably with other circulatio n models.