Myocardial oxygen consumption and substrate uptake in man during physiological and pathological volume load.

It is shown in trained and untrained healthy individuals that the energy requirement of the physiologically hypertrophied heart is lower at rest and even more pronounced during submaximal heavy exercise compared to the non-hypertrophied state. This difference exceeds the changes which could have been anticipated by deviations in hemodynamics and total heart weight. In patients with mild or moderate aortic insufficiency the energy expenditure of the pathologically hypertrophied heart per unit tissue mass is comparable to the non-hypertrophied state at rest or during exercise. It is increased in severe aortic regurgitation or additional myocarditis. The transition from compensation to failure may be associated with a steep decreased of the metabolic and flow reserve of the whole heart.