Assessment of the mechanism of mitral valve prolapse in children: An echocardiography study.

Background: The high complexity of mitral valve anatomy and function in mitral valve prolapse (MVP) is not yet fully understood.

Objective: The purpose of this study was to analyze each part of the mitral valve apparatus in children to determine its impact on the presence of MVP and to assess the interaction between the coaptation length (CL) and mitral regurgitation severity.

Methods: We prospectively analyzed transthoracic echocardiograms of 60 patients with MVP (mean age 9.8 ± 3.1 years). We compared these patients with 60 control patients without disease. We determined length of leaflets, chordal length, tenting area, coaptation CL, the intrapapillary muscle distance (IPMD) and relation between CL and severity of mitral regurgitation (MR).

Results: For patients with MVP, the posterior mitral leaflet (PML) was significantly enlarged 13.9 ± 4.1 mm versus 10.7 ± 3.5 mm (p < .01), the primary chordal length was significantly decreased 15.4 ± 3.61 mm versus 17.6 ± 3.8 mm (p < .02), and IPMD was significantly greater 18.1 ± 2.7 mm versus 16.6 ± 4.3 mm (p < .03). The difference between CL for both the anterior and posterior mitral leaflets correlated positively with MR (r = .249, p < .05). A greater than 4 mm CL correlated with at least MR (sensitivity 100%, specificity 72%) and greater than 5 mm correlated with at least moderate MR (sensitivity 100%, specificity 60%).

Conclusion: The majority of pediatric patients with mitral valve prolapse have structural abnormalities that are defined well by echocardiography. In addition to the presence of prolapse and regurgitation, routine assessment of leaflet length, thickness, chordal length and papillary muscle distance is fundamental for patients with MVP.