Evaluation of Subendocardial Ischemia in Valvar Aortic Stenosis in Children

Abstract

An index of myocardial oxygen supply/demand was calculated from the left ventricular and aortic pressure tracings in 80 infants and children with isolated valvar aortic stenosis. Supply was estimated by multiplying the area between aortic and left ventricular pressures during diastole (DPTI) by arterial oxygen content (C). Demand was estimated from the area under the left ventricular tracing during systole (SPTI). The oxygen supply/demand ratio was expressed as: DPTI X C/SPTI. A ratio 2/m², an increasing number of patients develop ratios 2/m² but heart rates 100/minute and severe stenosis all have ratios consistent with subendocardial ischemia. Supply/demand ratios 10. It is concluded that in severe valvar aortic stenosis heart rate is a critical factor in the development of a reduction in the oxygen supply/demand ratio consistent with subendocardial ischemia. Exercise induced tachycardia may be useful in identifying patients with severe valvar aortic stenosis and borderline ischemia who have normal T waves at rest.