DIVERGENT CARDIAC RESPONSE TO EXERCISE IN ESSENTIAL-HYPERTENSION VS. NORMOTENSION AND THE EFFECT OF ENALAPRIL

The aims of this study were to examine (1) the cardiac response to exe rcise in essential hypertension and (2) the effect of long-term enalap ril treatment on cardiac reserve. Ten normotensive control subjects an d 15 patients with moderate, essential hypertension underwent radionuc lide ventriculography during graded, supine exercise (0 W-50 W-100 W). The hypertensive patients were studied during monotherapy using hydro chlorothiazide and 3 and 12 months after supplementation with enalapri l 10-40 mg o.d. During exercise, the control subjects demonstrated a 1 7% increase in left ventricular ejection fraction (LVEF) mediated by a 30% decrease in end-systolic volume, a small increase in stroke volum e and a minor biphasic (increase-decrease) change in end-diastolic vol ume. In the hypertensive patients, both the end-diastolic and the end- systolic volume increased substantially with no increase in LVEF, alth ough stroke volume increased by 33%. Long-term therapy with enalapril induced only a minor change towards a more normal pattern of cardiac r esponse to exercise. The hypertensive patients increased their stroke volume during exercise by recruiting preload reserve instead of increa sing contractility. Long-term treatment with enalapril had little, if any, effect on this abnormal cardiac response.