Objective: It has been suggested that in some settings, heart failure (HF) may occur with normal ejection fraction (EF) as a consequence of undetected systolic dysfunction. However, others have argued that this can only occur in the presence of diastolic dysfunction. We therefore sought to determine the contribution of diastolic dysfunction in an animal model of HF with normal EF. Methods and results: Limited myocardial injury was induced in 21 dogs chronically instrumented to measure hemodynamics and LV properties by daily coronary microembolization (115 Am beads) until LV end diastolic pressure (LVEDP) was 16 mm Hg. Nine dogs developed HF within 16 days (LVEDP 12+2 vs. 21+2 mm Hg, p < 0.001) with no significant change in dP/dtmax (2999+97 vs. 2846+189 mm Hg/s), mean arterial pressure (103+4 vs. 100+4 mm Hg), EF (57+5% vs. 53+4%) or Ees (end-systolic elastance, 3.1+0.9 vs. 2.9+0.8 mm Hg/ml) but with an 10 ml increase in Vo (14+12 vs. 25+16 ml; p < 0.01). The EDPVR and time constant of relaxation (s, 25+3 vs. 28+3 ms) did not change significantly. These animals were hemodynamically stable out to 3 1/2 months. Neurohormonal activation occurred (elevations of NE, AngII, BNP) and there was intravascular volume expansion by 16% ( p < 0.05). Conclusions: A small amount of myocardial injury can lead to neurohormonal activation with intravascular volume expansion and elevation of LVEDP in the absence of reductions in dP/dtmax or EF and without diastolic dysfunction. Thus, HF with preserved EF does not a priori equate with diastolic heart failure.
Tags: EDPVR, EF, heart, heart failure, hemodynamics, HFNEF, HFPEF, injuries, methods, microembolization, model, NO, pressure, relaxation, Time, volume