We studied the ventricular pressure-area relationship in 22 pediatric HFpEF patients and 22 control subjects before and after dobutamine infusion and during abdominal compression. Coronary supply/demand balance was assessed by subendocardial viability ratio (SEVR) calculated from the aortic pressure waveform.
Compared with controls, the HFpEF patients had significantly higher end-systolic (Ees) and arterial (Ea) elastance. Increased ventricular diastolic stiffness also occurred in the HFpEF patients, resulting in modest elevation of end-diastolic pressure (EDP) at rest (13.6 ± 4.3 vs. 7.3 ± 2.3 mm Hg, P < 0.0001). The difference in EDP became more evident with a preload increase through abdominal compression, indicating a limited diastolic reserve in HFpEF patients (EDP changes; 11.3 ± 6.2 for HFpEF vs. 3.4 ± 0.6 mm Hg for controls, P = 0.016). The HFpEF patients exhibited impaired beta-adrenergic reserve in ventricular contractility and ventricular-arterial coupling in response to dobutamine infusion. SEVR was significantly lower in the HFpEF (0.64 ± 0.11) than in the control (0.79 ± 0.07, P < 0.0001) and was significantly correlated with LV diastolic stiffness and dobutamine-induced changes in ventricular contractility.
HFpEF in children involves higher ventricular-arterial stiffness at rest as well as impaired systolic and diastolic reserve, which closely correlate with impaired coronary supply/demand balance.