Left ventricular systolic wall stress as a primary determinant of myocardial oxygen consumption: Comparative studies in patients with normal left ventricular function, with pressure and volume overload and with coronary heart disease

Summary

Left ventricular dynamics, coronary blood flow (V_cor), and myocardial oxygen consumption (MVO₂) were determined in normal patients (N), in chronic pressure overload (aortic stenosis, AS), in chronic volume overload (aortic incompetence, AI), and in coronary heart disease (CHD). Peak systolic and enddiastolic wall stress were increased in AS and AI by 26–52 per cent, the systolic stress being preferably increased in AS, whereas enddiastolic stress was markedly greater in AI. V_cor and MVO₂ were elevated in both groups by 45–55 per cent (p < 0.001). Sufficient correlation was present between peak systolic wall stress and the MVO₂ (r = 0.82). Since at a given wall stress the MVO₂ was somewhat increased in AI and AS when compared with N and CHD, the considerable enhancement of the rate of pressure development (AS) as well as of the external cardiac work (AI) may contribute to the increase in overall oxygen consumption. It is concluded that systolic wall stress represents a primary determinant of MVO₂ in pressure and volume overload and that the MVO₂ increases in these diseases when hypertrophy becomes inappropriate with regard to the pressure and volume demands imposed to the left ventricle.

Supported by Deutsche Forschungsgemeinschaft