[Left ventricular function in dilated cardiomyopathy. Noninvasive determination of end-systolic stress-diameter and shortening fraction-stress relations].
The ejection fraction and fractional shortening are parameters of left ventricular function dependent on the conditions of load. They are not perfect indices of myocardial contractility. The study of the relationships between stress and diameter and fractional shortening and stress in end-systole provides a better means of assessing the contractile state of the myocardium. The relationships between end-systolic stress-diameter and end-systolic stress-fractional shortening were studied non-invasively in 10 normal subjects (Group I) and 7 patients with severe dilated cardiomyopathy (Group II). End-systolic longitudinal stress of the left ventricle was calculated from Grossman's formula by coupling automatic measurement of blood pressure (cuff method) with simultaneous M mode recordings guided by 2D echocardiography. The line of regression of end-systolic stress-end-systolic diameter was determined in all cases from a series of 14 points obtained after sublingual administration of 10 mg of isosorbide dinitrate. The line of regression of fractional shortening-end-systolic stress was established in both groups by using the values observed under basal conditions and at the peak of action of the isosorbide dinitrate. The following results obtained: Under basal conditions, patients in Group II had greater end-diastolic diameters (69 +/- 8 vs 49 +/- 4 cm, p less than 0.01), greater end-systolic diameters (61 +/- 8 vs 33 +/- 4 mm, p less than 0.001) and higher end-systolic stress (140 +/- 54 vs 67 +/- 13 10(3) dyn/cm2, p less than 0.001). Fractional shortening was lower in Group II than in Group I (12 +/- 5 vs 33 +/- 5%, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)