Correlates of aortic distensibility in chronic aortic regurgitation and relation to progression to surgery.

Abstract

Aortic distensibility decreases with increasing age. Patients with chronic aortic regurgitation eject a large stroke volume into the proximal aorta. A decrease in distensibility of the aorta may impose a higher afterload on the left ventricule and may contribute to deterioration of left ventricular function over time. Accordingly, aortic distensibility was measured in 33 patients aged 13 to 73 years who had chronic isolated aortic regurgitation with minimal or no symptoms. Ascending aortic diameter was measured 4 cm above the aortic valve by two-dimensional echocardiography and pulse pressure was measured simultaneously by sphygmomanometry. Aortic distensibility was calculated as (Change in aortic diameter between systole and diastole/End-diastolic diameter)/Pulse pressure. Left ventricular systolic wall stress and mass were derived from standard M-mode echocardiographic measurements. Left ventricular volumes and ejection fraction were measured by radionuclide ventriculography. Aortic distensibility decreased logarithmically with increasing age (r = -0.62, p less than 0.001) and also correlated inversely with systolic wall stress, left ventricular mass and end-diastolic volume. Patients who eventually underwent aortic valve replacement for symptoms of left ventricular dysfunction had significantly lower aortic distensibility than did those who did not yet require valve replacement: 0.09 +/- 0.08 vs. 0.22 +/- 0.19 x 1/100 (1/mm Hg) (p less than 0.05). Thus, the reduced aortic distensibility that occurs with increasing age may contribute to the gradual left ventricular dilation and dysfunction seen in patients with chronic aortic regurgitation.