A Comprehensive Physiological Model of Circulation Enables Automatic Piloting of Hemodynamics in Patients with Acute Heart Failure

A comprehensive physiological model of the whole circulation is mandatory to quantitatively diagnose pathophysiology and to guide an appropriate treatment. Such a model would enable automatic piloting of hemodynamics in patients with acute heart failure. By extending Guyton´s model, so as to deal with heart failure predominantly affecting left heart and to quantify left atrial pressure, we constructed such a model consisting of a venous return (VR) surface and a cardiac output (CO) curve. VR surface, the integrated property of systemic and pulmonary vascular beds, relates VR and left and right atrial pressures (PLA, PRA) linearly as VR = V/W - GRPRA- GLPLA, given total blood volume (V). CO curve, the pumping ability of hearts, relates CO and either PLAor PRAapproximately by logarithmic functions, respectively, as CO = SL[ln (PLA- BL) + CL] = SR[ln (PRA- BR) + CR]. The slopes (SRand SL) of CO curve mainly describes the pump performance. W, GR, GL, BR, BL, CRand CLare parameters. We validate the model with animal experiments. Parameters W, G´s, B´s and C´s were relatively constant in 19 dogs. In other 8 dogs, with or without acute left heart failure, we determined V and S´s from a single set of CO, PRA, PLAand standard parameter values. We then predicted hemodynamics (CO, PRA, PLA) for altered V from –8 to +8 ml/kg. We identified standard values of parameters as W (0.13 min), GR(19.6 ml/min/kg/mmHg), GL(3.5 ml/min/kg/mmHg). BL(2.1 mmHg), CL