Peak left ventricular pressure/volume (Emax) during exercise in control subjects and children with left-sided cardiac disease

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Abstract
The peak ratio of left ventricular systolic pressure/systolic volume (PV) has been shown to be a close approximation to Emax, an index of contractility independent of both preload and afterload. We studied 17 children with left-sided cardiac disease during catheterization by a combined high-fidelity catheter and m-mode echocardiographic technique. Emax, indexed for body surface area, was calculated at rest and during supine exercise at 25% and 50% of maximal upright workload. In addition, we studied 15 control subjects with a noninvasive approximation of peak P/V, the peak systolic LV pressure/smallest systolic LV volume. Patients with left ventricular pressure overload showed an increased Emax, value at rest and a further increase with exercise. Patients with left ventricular volume overload or cardiomyopathy had a normal value of Emax, at rest and had only small increases with exercise. Patients with both volume and pressure overload had a resting Emax, value that was increased, but no further increase occurred with exercise. Emax, in children seems to be a sensitive index of contractility during physiologic stress and can be used to assess left ventricular functional reserve capacity both pre- and post-operatively.