Differences in left ventricular adaptation to chronic mitral and aortic regurgitation.

For comparable volume load, impedance to ejection of the regurgitant volume in AR exceeds that in MR. To determine whether this load difference results in differences in PLVH and ejection performance, we studied consecutive, untreated, asymptomatic patients (11 in each group) by echocardiography and Doppler. Mean LVID, SBP, h, and FS were, respectively, in AR vs MR: 60.3 +/- 3.1 mm vs 62.0 +/- 2.3 mm (p = NS), 152 +/- 7.1 mm Hg vs 125 +/- 6.4 mm Hg (p less than 0.005), 12.1 +/- 0.4 mm vs 10.5 +/- 0.6 mm (p less than 0.04), and 0.38 +/- 0.02 vs 0.43 +/- 0.02 (p = NS). The h/R ratio reflects the PLVH-0.41 +/- 0.02 in AR and 0.34 +/- 0.02 in MR (p less than 0.02). The FS correlates positively with h/R in either lesion, but was higher in MR for any given h/R. The difference in loading conditions imposed by both lesions is associated with a difference in the PLVH as well as in ejection performance.