Systolic stress, coronary hemodynamics and metabolic reserve in experimental and clinical cardiac hypertrophy.

The degree of LV hypertrophy may be determined by the relationships between mass-to-volume ratio and systolic wall stress. Systolic wall stress correlates directly with the MVO2 and inversely with LV function. In chronic hypertrophic heart disease (a) normal stress, (b) low stress and (c) high stress hypertrophy may occur. Low stress hypertrophy has normal LV function and normal or decreased MVO2, whereas high stress hypertrophy mostly has depressed function and an increased MVO2. The MVO2 is directly correlated to LV mass. This relationship is influenced by the variable degree of LV mass, by the mass-to-volume ratio and by inotropic interventions. Systolic stress reserve, the ratio of maximum to instantaneous systolic wall stress, averages 4.5. Similar reserves are present for the coronary (4.9) and for the metabolic reserve (4.6). It is concluded that systolic wall stress represents one of the major determinants of LV performance and of myocardial oxygen consumption.