DEPRESSED MECHANOENERGETICS AND COMPENSATORY RESPONSES IN IDIOPATHIC DILATED CARDIOMYOPATHY

The aim of this study was to clarify that the depressed mechanoenerget ics in patients with idiopathic dilated cardiomyopathy (DCM) resulted from compensation for the decreased contractility. The study populatio n consisted of eight control subjects, with normal left ventricular si ze and ejection fraction and 31 patients with DCM. Left ventricular en d-systolic elastance (Ees), effective arterial elastance (Ea), externa l work (EW), and the pressure-volume area (PVA) were measured, using a dual-field volume conductance catheter equipped with a micromanometer -tipped catheter. Ea/Ees was evaluated as ventriculoarterial coupling. Normal hearts worked at almost optimal condition (defined as Ea/Ees = 1/2), while ventriculoarterial coupling was far from the optimum (Ea > Ees) in patients with DCM. Ees in patients with DCM was less than th at in control subjects; however, Ea was similar in the two groups. The mismatch of Ea/Ees observed in DCM leads to depressed mechanoenergeti cs as a result of the compensatory response to maintain adequate blood pressure. Volume enlargement plays an important role in maintaining a dequate blood pressure and cardiac output in the course of chronic det erioration of contractility.