Describing the pumping heart as a pressure source

The pumping heart is described by a new mathematical approach which conside rs the heart as a pressure source depending on time, volume and flow. This new approach allows a separation between isovolumic (non-ejecting) and ejec ting heart properties. The computed results cover most of the features of t he human ventricle during normal and altered vascular conditions. It is sho wn that the time-varying elastance concept is disqualified as an independen t description of the heart, it follows from isovolumic heart properties and an ejection effect which consists of positive and negative effects of vent ricular blood ejection. (C) 2001 Academic Press.