Pathophysiology and Natural History Valvular Heart Disease

We studied the relationship between myocardial contractile state and left ventricular functional response to exercise in 14 asymptomatic patients with isolated moderate-to-severe aortic regurgitation and six control subjects. The slope of the systolic blood pressure-left ventricular endsystolic volume (pressure-volume) relationship determined by radionuclide ventriculography during angiotensin infusion was used as an indirect measure of myocardial contractility and was compared with left ventricular ejection fraction at rest and during both isometric handgrip and dynamic bicycle exercise. The slope of the pressure-volume relationship was significantly lower in patients with aortic regurgitation than in the control subjects (1.75 + 0.57 vs 2.78 + 0.42, p < 0.01). The slope correlated exponentially with resting ejection fraction and was linearly related to changes in left ventricular ejection fraction during both handgrip and bicycle exercise. In patients with aortic regurgitation, resting ejection fraction may overestimate myocardial function. The slope of the pressure-volume relationship measured during afterload stress and left ventricular ejection fraction response to exercise intervention more reliably reflect the degree of left ventricular dysfunction. Circulation 71, No. 1, 31-38, 1985. PATIENTS with aortic regurgitation may remain asymptomatic for many years even with significant left ventricular dysfunction" 2 and the optimal timing of aortic valve replacement is controversial. Left ventricular ejection fraction is often normal at rest,SA but may respond abnormally to exercise.5-9 The mechanism of the abnormal response is difficult to define because of markedly altered loading conditions in such patients. The slope of end-systolic pressure-volume relationship has been shown to be a sensitive index of myocardial contractile state independent of preload.'-'3 The utility of this measurement as an index of myocardial contractility in man has been enhanced since systolic blood pressure measured noninvasively can be substituted for left ventricular end-systolic pressure without significantly altering its validity.'3-'7 The purpose of this study was to determine the systolic blood pressure-left ventricular end-systolic volume (pressureFrom the Hallstrom Institute of Cardiology, Department of Nuclear Medicine, Royal Prince Alfred Hospital, University of Sydney, Sydney, Australia. Address for correspondence: Professor David T. Kelly, Hallstrom Institute of Cardiology, Royal Prince Alfred Hospital, Camperdown N.S.W. 2050, Australia. Received July 2, 1984; revision accepted Sept. 13, 1984. volume) relationship in patients with aortic regurgitation and to correlate this parameter with left ventricular performance during both isometric handgrip and dynamic bicycle exercise. Methods Study patients. Fourteen asymptomatic patients (13 men and one woman, mean age 36 years, range 24 to 44) with isolated moderate-to-severe aortic regurgitation were studied. Four patients had undergone cardiac catheterization and had aortic regurgitation of angiographic grade III out of IV, with no peak systolic pressure gradient, no mitral regurgitation, and normal coronary arteries. The remaining 10 patients had clinical signs of isolated moderately severe aortic regurgitation, with pulse pressure of more than 55 mm Hg and cardiomegaly on radiographs. In all 10 patients echocardiograms showed diastolic fluttering of the mitral valve, left ventricular end-diastolic dimension greater than 6.0 cm, aortic leaflet separation of more than 2.0 cm, and average diastolic wall thickness less than 1.1 cm. No patient had evidence of any other valve disease and none had angina or segmental wall motion abnormalities on radionuclide ventriculograms obtained at rest and during exercise. All patients were in sinus rhythm and none were on medication. Six patients (five men and one woman, mean age 44 years, range 36 to 53) with angiographically normal left ventricular function and coronary arteries served as the control group. All had undergone previous testing because of atypical chest pain. None had evidence of valvular heart disease or were on medications and all were in sinus rhythm. Written informed consent was obtained from all patients and Vol. 71, No. 1, January 1985 31 by gest on A uust 4, 2017 http://ciajournals.org/ D ow nladed from