Key Points
- To examine how variations in the contractile state of the myocardium influence the relationship between ventricular preload and maximal rate of pressure rise.
- Assessed isolated canine heart-lung preparations (N=33) across varying stages of functional deterioration and following calcium administration.
- Measured right and left ventricular dP/dt max alongside aortic flow across varying levels of end-diastolic pressure to construct ventricular function curves.
- The slope of dP/dt max preload dependence was steepest shortly after isolation, decreased progressively as the heart deteriorated, and increased following calcium administration, showing a linear correlation between the right and left ventricles.
- Slopes of preload dependence for dP/dt max and aortic flow correlated closely in individual hearts under varying contractility and across 33 distinct isolated hearts.
- The quantitative estimation of relative contractility changes via dP/dt max varied according to the specific end-diastolic pressure level selected.
Structured PICO
PPopulation33 isolated canine heart-lung preparations
IInterventionApplication of calcium and varying contractile states (deterioration)
OOutcomeRelation between dP/dt max and end-diastolic pressure (preload dependence)surrogate
In canine models, the preload dependence of dP/dt max is a reliable measure of myocardial contractility, though its quantitative results are influenced by the chosen end-diastolic pressure level.