Instantaneous changes in arterial compliance reduce energetic load on left ventricle during systole

neous changes in arterial compliance reduce energetic load on left ventricle during systole. Am. J. PhysioZ. 267 (Heart Circ. Physiol. 36): H24-H32, 1994.We tested the hypothesis that arterial compliance changes during each cardiac cycle, and that these instantaneous changes are beneficial for energy conservation. Using an adaptive identification procedure, we were able to obtain an instantaneous impulse-response repre-sentation of the arterial system. By assuming a three-element windkessel model, we obtained the instantaneous compliance. The arterial compliance remained relatively constant during diastole but increased during systole. The calculated time trajectory was compared with an optimal compliance calcula-tion based on minimum ventricular ejection energy criteria. The two compliance trajectories followed similar paths. We conclude that increases in arterial compliance during systole reduce the energy demands on the left ventricle. arterial mechanics; ventricular vascular coupling; rheology; hemodynamics; pigs IF WE THINK of the left ventricle as a mechanical pump, the arterial system can be considered its load. In con-trast to a conventional pump-load system, it has been postulated that the left ventricle and the arterial system are “coupled ” to optimize the basic function according to some optimality criterion (8, 13, 21, 23). The arterial compliance is one of the elements of the ventricular load whose effects on ventricular-vascular coupling has been widely investigated. Most studies have assumed a con-stant compliance during the cardiac cycle, at leas