Serial assessment of ventricular performance after valve replacement for aortic stenosis.
The purpose of this investigation was to examine changes in cardiac function after aortic valve replacement in patients with chronic aortic stenosis. Eleven consecutive patients with severe aortic stenosis were studied by radionuclide angiocardiography before; after 1, 2, 4, 6, 8, and 18 to 24 hours; and late after operation. Measurements of cardiac output, mean systemic blood pressure, heart rate, and left ventricular ejection fraction were similar before and immediately after operation. Significant early changes were observed in pulmonary capillary wedge pressure (27 to 13 mm Hg; p less than 0.001), left ventricular end-diastolic volume (214 to 166 ml; p less than 0.01), pulmonary blood volume (700 to 462 ml/m2; p less than 0.01), and right ventricular ejection fraction (0.54 to 0.68; p less than 0.001). A radionuclide angiocardiogram acquired a mean of 3.5 months after operation revealed increased resting left ventricular ejection fraction (0.49 to 0.58; p = 0.05), decreased end-systolic volume (91 to 59 ml; p less than 0.05), and decreased end-diastolic volume (166 to 135 ml; p less than 0.02) compared with measurements before operation. Improved exercise tolerance occurred in nine patients. The significant change in function during the early period after valve replacement was a maintenance of baseline cardiac output at a reduced level of left ventricular filling. Several months after operation, left ventricular volumes decreased further, resting ventricular performance was improved, and improved maximal exercise function was demonstrated. These changes probably reflected morphologic normalization after aortic valve replacement.
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