[Characteristic findings of mitral valve and mechanism of mitral valve prolapse in Marfan syndrome].
To elucidate the mechanism of generation of mitral valve prolapse (MVP) in Marfan syndrome, we studied the relations of the length of the anterior mitral leaflet to the diameter of the mitral ring. In 13 cases of Marfan syndrome associated with MVP (Group I), 21 of isolated MVP (Group II), and 24 controls free from valvular disease (Group C), the maximal length of the anterior mitral leaflet (L) and the end-diastolic and end-systolic diameters of the mitral ring (Rd and Rs) were measured in the long-axis views on two-dimensional echocardiograms. In addition, the measurements were corrected with the body surface area; designated as L(c), Rd(c) and Rs(c), respectively. Furthermore, L/Rd and L/Rs, and the percentage of shortening of the mitral ring in systole, (Rd-Rs)/Rd X 100, were obtained. The body surface area in Group I was greater than that in Group II (p less than 0.05), but there was no significant difference between Groups II and C. The L was obviously different between Groups I and II or C (p less than 0.001, respectively). Similarly, there was a significant difference in L(c) between Groups I and II (p less than 0.02) or C (p less than 0.001), indicating the remarkably long anterior mitral leaflet in Group I. The Rd in Group I and II was greater than that in Group C (p less than 0.01 and p less than 0.02, respectively), while there was no significant difference in the Rd(c) among the 3 groups. There was also no statistical difference in either Rs or Rs(c) among the 3 groups. Both L/Rd and L/Rs in Group I were remarkably higher than those in Groups II and C (p less than 0.001, respectively), whereas these parameter did not differentiate Group II from Group C. (Rd-Rs)/Rd X 100 was higher in Group I than that in Groups II and C (p less than 0.05 and p less than 0.01, respectively), but it was not significantly different between Groups II and C. These results suggested that one of the probable mechanisms of generation of MVP in Marfan's syndrome is the redundant mitral valve resulting from a remarkably long leaflet and increased systolic shortening of the enlarged mitral ring.
D000293:Adolescent; D000328:Adult; D000368:Aged; D004452:Echocardiography; D005260:Female; D006801:Humans; D008297:Male; D008382:Marfan Syndrome / Q000150:complications* / Q000473:pathology; D008875:Middle Aged; D008943:Mitral Valve / Q000473:pathology*; D008945:Mitral Valve Prolapse / Q000175:diagnosis / Q000209:etiology*; D009200:Myocardial Contraction