[Evaluation of left ventricular function in patients with dilated cardiomyopathy by exercise echocardiography]

In order to evaluate left ventricular function of dilated cardiomyopathy, 24 patients and ten healthy subjects were studied by exercise echocardiography. The patients with dilated cardiomyopathy were classified into 3 groups according to the presence or absence of mitral regurgitation and the severity of left ventricular dilatation: Group I was consisted of five cases with mitral regurgitation. Group II was consisted of seven cases without mitral regurgitation who had marked left ventricular dilatation, where the left ventricular end-diastolic dimension index (DdI) was greater than 46 mm/m2 and left ventricular end-systolic dimension index (DsI) was greater than 40 mm/m2. Group III was consisted of 12 cases without mitral regurgitation who had moderate left ventricular dilatation, where the DdI was less than 46 mm/m2 or DsI was less than 40 mm/m2. The ergometer exercise tests were performed for 3 min at 25 watts in a supine position. There was no significant differences of exercise-induced increases in heart rate, elevations of systolic blood pressure and increases of rate pressure product, respectively, between healthy subjects and each group of dilated cardiomyopathy. In healthy subjects, both DdI and DsI were unchanged on exercise. In Group I, DdI was unchanged but DsI decreased (p less than 0.02), thus percent fractional shortening of the left ventricle (delta D) was increased (p less than 0.05). In Group II, both DdI and DsI were unchanged. In Group III, DdI was increased (p less than 0.05) while DsI was unchanged, thus delta D was increased (p less than 0.02). These results suggested that the left ventricle is able to respond to exercise by its further dilatation (increase of preload) in mild to moderate dilated cardiomyopathy (Group III). On the other hand, in cases with marked left ventricular dilatation (Group II), the further dilatation is not induced. The same was true in dilated cardiomyopathy with mitral regurgitation (Group I), where the left ventricle had almost the same size as in Group II, although changes in DsI and delta D were not evaluated precisely because of the associated regurgitation.