Author + information
- Received January 8, 1996
- Revision received March 27, 1996
- Accepted April 9, 1996
- Published online August 1, 1996.
- Eric K. Louie, MD, FACC*,
- David Langholz, MD, FACC,
- William J. Mackin, MD, FACC,
- Diane E. Wallis, MD, FACC,
- William R. Jacobs, MD and
- Patrick J. Scanlon, MD, FACC
- ↵*Address for correspondence: Dr. Eric K. Louie, Professor of Medicine, Loyola University Medical Center, 2160 South First Avenue, Maywood, Illinois 60153.
Objectives. This prospective, blinded transesophageal echocardiographic study was performed to determine the relative contributions of leaflet redundancy and overlap versus intrinsic tissue thickening as mechanisms for the apparent increase in diastolic thickness of the mitral valve.
Background. Increased diastolic thickness of the mitral valve has been identified as an echocardiographic feature that predicts subsequent adverse sequelae in patients with mitral valve prolapse (MVP).
Methods. Eleven patients with clinical and transthoracic echocardiographic evidence of MVP and 11 age-matched control subjects underwent protocol transesophageal echocardiography to image the mitral valve in two orthogonal planes and to measure its thickness in systole and diastole.
Results. Maximal diastolic width of the slack, unloaded anterior leaflet was significantly greater in patients with MVP than in control subjects (mean ± SD: 0.64 ± 0.20 cm vs. 0.30 ± 0.04 cm, p < 0.001). Similarly, diastolic posterior leaflet width was greater in patients with MVP (0.67 ± 0.39 cm vs. 0.31 ± 0.06 cm, p < 0.01). In contrast, minimal systolic width of the distended pressure-loaded mitral valve was not significantly different between patients with MVP and control subjects for either the anterior (0.22 ± 0.05 cm vs. 0.20 ± 0.04 cm, p = NS) or the posterior (0.25 ± 0.07 cm vs. 0.24 ± 0.05 cm, p = NS) leaflets. The percent change in leaflet width from diastole to systole (%ΔW), an index of the contribution of dynamic factors (e.g., leaflet redundancy and overlap) to the apparent increase in diastolic leaflet thickness, was significantly greater in patients with MVP than in control subjects for both the anterior (%ΔW 62 ± 13% vs. 34 ± 16%, p < 0.001) and the posterior (%ΔW 54 ± 19% vs. 22 ± 21%, p < 0.005) leaflets.
Conclusions. The apparent increase in diastolic mitral leaflet thickness in patients with MVP versus control subjects is largely attributable to dynamic factors such as leaflet redundancy, overlap and deformation. During diastole, when the mitral leaflets are slack and unstressed, the leaflets appear markedly thickened in patients with MVP. In contrast, during systole, when developed intraventricular pressure distends the leaflets, causing them to stretch and balloon into the left atrium, the intrinsic tissue thickness is much less than that measured in diastole. These findings have important implications for the morphologic criteria used to diagnose MVP and the potential pathophysiologic mechanisms for adverse sequelae in this syndrome.
This study was presented in part at the 44th Annual Scientific Session of the American College of Cardiology, New Orleans, Louisiana, March 1995.
- Received January 8, 1996.
- Revision received March 27, 1996.
- Accepted April 9, 1996.
- American College of Cardiology