Altered LV inotropic reserve and mechanoenergetics early in the development of heart failure

tered LV inotropic reserve and mechanoenergetics early in the development of heart failure. Am. J. Physiol. Heart Circ. Physiol. 278: H698–H705, 2000.—To test the hypothesis that alterations in left ventricular (LV) mechanoenergetics and the LV inotropic response to afterload manifest early in the evolution of heart failure, we examined six anesthetized dogs instrumented with LV micromanometers, piezoelectric crys-tals, and coronary sinus catheters before and after 24 h of rapid ventricular pacing (RVP). After autonomic blockade, the end-systolic pressure-volume relation (ESPVR), myocar-dial O2 consumption (MV̇O2), and LV pressure-volume area (PVA) were defined at several different afterloads produced by graded infusions of phenylephrine. Short-term RVP resulted in reduced preload with proportionate reductions in stroke work and the maximum first derivative of LV pressure bu