Diagnostic Methods Ventricular Performance

We studied the hemodynamic response to supine bicycle exercise in 20 patients late (10 + 2 years) after aortic valve replacement (for aortic stenosis in 12 patients, aortic insufficiency in six patients, and for combined stenosis and insufficiency in two patients). The pulmonary artery wedge pressure was obtained with a pulmonary artery balloon catheter, and left ventriculography was performed by digital-subtraction angiography after injection of radiographic contrast into the pulmonary artery. These patients were compared with 11 control subjects with no or minimal cardiac disease studied routinely for evaluation of chest pain in whom left ventricular end-diastolic pressure and a direct contrast ventriculogram were obtained. Compared with the control population, the study population had similar left heart filling pressures (7 + 3 vs 9 + 3 mm Hg, NS), but higher left ventricular ejection fractions (75 + 7% vs 67 + 7%, p < .02) and higher left ventricular muscle mass indexes (106 + 28 vs 85 + 9 g/m2, p < .01). Elevated myocardial muscle mass led to lower systolic wall stress in the study population than in the control subjects (254 65 vs 320 49 103 dynes/cm2, p < .01) and might explain the higher ejection fraction observed. Fourteen patients had a normal response to exercise (with left heart filling pressures of 16 + 4 vs 18 + 2 mm Hg for control subjects, NS; and left ventricular ejection fraction of 77 8% vs 73 + 5% for control subjects, NS). However, while the remaining six patients had a normal exercise left ventricular ejection fraction (72 + 9%, NS), they had an abnormal rise in left heart filling pressure (33 + 8rmm Hg, p < .01). Preoperatively these patients also had higher left ventricular midand end-diastolic pressures at similar diastolic volumes, suggesting a decrease in chamber compliance. Thus, late after aortic valve replacement there is a subgroup of patients who, despite normal hemodynamics and normal left ventricular systolic function as assessed by the left ventricular ejection fraction at rest, have an abnormal response to exercise characterized primarily by a substantial rise in left heart filling pressures. Preoperatively this group also has a decrease in diastolic chamber compliance despite nearly normal left ventricular ejection fractions. This abnormality appears to result from a primary derangement of diastolic function that is not evident at rest. Circulation 77, No. 3, 613-624, 1988. AORTIC VALVE REPLACEMENT has produced a dramatic change in the "natural" history of aortic insufficiency and aortic stenosis. Improvement in survival,1' 2 New York Heart Association class,3 and resting hemodynamics,3-9 even in patients with preoperative left ventricular dysfunction,3'4'5' 7' 9 has From the Medical Policlinic, Division of Cardiology, University Hospital, Zurich. Supported by a grant from the Swiss National Science Foundation. Address for correspondence: Hans P. Krayenbuehl, M.D., Chief, Division of Cardiology, Medical Policlinic, University Hospital, Raemistrasse 100, 8091 Zurich, Switzerland. Received Jan. 5, 1987; revision accepted Dec. 10, 1987. *Current address: Division of Cardiology, Albert Einstein College of Medicine, Bronx, NY. Presented at the Annual Scientific Sessions of the American Heart Association in Dallas, November 1986. Vol. 77, No. 3, March 1988 been well documented. However, it remains the substitution of one disease state for another,10 with relative and persistent, although not progressive, aortic stenosis from the artificial valve."11 12 Moreover, there remains the significant concern that the prior hemodynamic insult, with its attendant myocardial hypertrophy,4 may produce permanent myocardial injury and dysfunction. In support of this we have reported persistent morphologic abnormalities early after aortic valve replacement13 that have correlated with abnormalities in diastolic function. In this study, we used dynamic exercise to evaluate cardiac function late (10 + 2 years) after successful aortic valve replacement in patients with normal left ventricular systolic function. 613 by gest on A ril 4, 2017 http://ciajournals.org/ D ow nladed from