[Anomalous ventricular contractile performance in experimental chronic aortic insufficiency in the dog]

Hemodynamics and right (RV) and left (LV) ventricular performances of anaesthetized, closed-chest animals were studied in normal control dogs (N) and in dogs with aortic insufficiency (AI), the latter intervention being performed 33 months before verification. In dogs with AI, LV was hypertrophied (N = 49.6 +/- 6.3 g; AI = 98.7 +/- 10.1, p less than 0.001); forward stroke volume was slightly decreased (N = 20.0 +/- 2.2 ml; IA = 14.6 +/- 5.4 ml, p = NS);LV and diastolic pressure was increased (N = 9.4 +/- 1.4 mmHg; IA = 16.7 +/- 2.9, p less than 0.05); both RV and LV myocardial performace index (e.g. dP/dt max, peak VCE, Vmax) were normals. Relative pressure/velocity of shortening and wall stress/velocity of shortening relationships, however, were decreased, when measured during L.V. isovolumetric beats. LV stiffness of arrested heart was increased in proportions with hypertrophy extent. Thus, myocardial performance of chronically volume-overloaded heart appears to be depressed before the stage of the circulatory failure.