Systemvascular Resistance at Rest and Under Physical Exercise in Patients with Diastolic Heart Failure

Problem: The symptoms of patients with diastolic heart failure (DHI) manifest primarily in exertional intolerance. Research findings indicate that the interaction between the central and peripheral hemodynamics, the so-called "ventriculoartrial coupling", is disturbed. Increased system vascular resistance (SVR) is among the pathomechanisms discussed as the causate. We tested the hypothesis of a reduced SVR decrease under physical strain in patients with DHI compared to controls. Methods: Patients with symptomatic DHI and asymptomatic controls were examined under application of an inert gas rebreathing system (Innocor (TM)) combined with spiroergometry The primary endpoints were the SVR as well as the VO(2peak) measured at rest and under maximum exercise. Results: 10 patients with DHI (aged 69 +/- 10 years) and 9 controls (aged 60 +/- 10 years) were examined. The VO(2peak) was 15.4 ml/kg/min in the DHI group and 21.4 ml/kg/min in the control group (p = 0.0008), respectively. The SVR at rest was identical for both groups (24.1 mmHg/ml/min vs. 23.8 mmHg/ml/min, p = 0.92). Under maximum exercise, the SVR was 14.5 mmHg/ml/min (DHI) resp. 9.8 mmHg/ml/min (control group, p = 0.01; RQ 0.99 vs. 0.93; p = 0.13) and decreased by 39% in the group with DHI compared to a decrease by 58% in controls. A lowered decrease of the SVR correlated with a lowered VO(2peak) increase (r = 0.7, p = 0.001). Discussion: In patients with DHI, a diminished afterload decrease entails a disturbance of the ventriculoartrial interaction and is an aspect of performance limitation in patients with DHI. This supports the notion that DHI is a systemic disease of the heart, musculature and vessels.