Using a canine model of subcoronary valvular aortic stenosis, myocardial blood flow, high-energy phosphate content and mitochondrial function were determined in 8 hearts with chronic left ventricular hypertrophy. Fourteen normal hearts were used for control data. Myocardial blood flow was determined by injection of tracer microspheres. During cardiopulmonary bypass, left ventricular transmural biopsy specimens were taken for metabolic analyses. Subepicardial and subendocardial content of ATP and creatine phosphate (CP) were assayed. Respiratory control indices for isolated mitochondria were measured by use of NAD-linked and FAD-linked substrates. Endocardial blood flow, subendocardial high-energy phosphate content and respiratory control indices for NAD-linked substrate in the hearts with chronic left ventricular hypertrophy were significantly lower than the normal values. These data provide insight into the metabolic and myocardial blood flow abnormalities occuring in cardiac hypertrophy and altered response of hypertrophied hearts to ischemia.