Mitral valve dimensions and motion and familial transmission of mitral valve prolapse with and without mitral leaflet billowing

• Published in: Journal of the American College of Cardiology 1988-12, Vol.12 (6), p.1423-1431
• Main Authors: Pini, Riccardo, Greppi, Barbara, Kramer-Fox, Randi, Roman, Mary J., Devereux, Richard B.
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Cardiology. Vascular system; Echocardiography; Endocardial and cardiac valvular diseases; Female; Heart; Humans; Male; Medical sciences; Middle Aged; Mitral Valve - pathology; Mitral Valve - physiopathology; Mitral Valve Prolapse - etiology; Mitral Valve Prolapse - genetics; Mitral Valve Prolapse - pathology; Sex Factors
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/S0735-1097(88)80005-6

To test the hypothesis that mitral valve prolapse may be due either to billowing of mitral leaflets into the left atrium or to dynamic expansion of the mitral anulus, mitral leaflet and annular dimensions and motion were measured by computer-assisted two-dimensional echocardiography in 35 normal adults and 48 subjects with auscultatory and M-mode echocardiographic evidence of mitral prolapse. Among normal subjects, mitral leaflet and annular dimensions tended to be larger compared with body size or left ventricular size in women than in men. Mitral leaflet billowing was observed in 24 (50%) of 48 patients with mitral prolapse and 0 of 35 normal subjects (100% specificity). The 24 patients without leaflet billowing had greater systolic expansion of the mitral anulus (p < 0.0001) than did normal adults or patients with leaflet billowing (41 ± 14% versus 27 ± 12% and 22 ± 11%, respectively) and a significantly lower body mass index (p < 0.005 versus normal group). The ratio of anterior plus posterior mitral leaflet length to end-systolic annular diameter was lower in patients with prolapse without leaflet billowing than in normal subjects (1.09 ± 0.12 versus 1.19 ± 0.15, respectively, p < 0.01) or patients with leaflet billowing (1.21 ± 0.17, p < 0.05). Among 35 relatives with mitral prolapse in the families of 23 patients with prolapse, the pattern was the same as in the proband in 31 (89%) (p < 0.000002). These findings suggest that mitral valve prolapse occurs in two phenotypic patterns, characterized by either mitral leaflet billowing or dynamic systolic expansion of the mitral anulus in association with lean body build, which appear to represent genetically distinct entities of as yet unknown molecular cause. Furthermore, the larger mitral leaflets and anulus in relation to body size in normal women may contribute to the more consistent expression of mitral prolapse genes in women.