Key Points
- To determine whether the energetic predictions of the ventricular time-varying elastance model correspond to the intrinsic thermodynamic properties of isolated myocardium.
- Measured the force-length area and relaxation heat using thermopiles during isometric contractions of isolated rabbit papillary muscles at 20°C (n = 26).
- Modulated muscle mechanical performance across trials by systematically altering initial muscle length and extracellular calcium concentration.
- Demonstrated that the slope of the relation between force-length area and heat liberated during relaxation was not significantly different from unity (n = 26).
- Confirmed that the energetic equivalence prediction from whole-ventricle pressure-volume elastance behavior holds true at the tissue level in isolated papillary muscle.
Structured PICO
PPopulationIsolated rabbit papillary muscle at 20 degrees C (n=26)
IInterventionVariation of mechanical performance by altering initial muscle length and external calcium
OOutcomeRelation between force-length area and heat liberated in relaxationsurrogate
The energetic prediction of the time-varying elastance model developed for the whole left ventricle was confirmed by experiments on rabbit papillary muscle.