A perspective on myocardial contractility.

Myocardial contractile properties form the cornerstone of the heart's ability to pump blood. Efforts have been made to characterize these properties via classic elasticity theory concepts, which can lead to spurious results, as demonstrated by experiments measuring intramyocardial pressure. Two ways out of these difficulties are identified. One is to start at the cellular level, the other at the chamber level. The latter allows separation of ventricle (source) and arterial (load) effects on measured pressure and flow, distinct from previous definitions of ventricular contractility which tended to lump the two.