To reduce the missed diagnosis and misdiagnosis of mitral valve cleft by investigating the two-dimensional transthoracic echocardiography (2D-TTE) characteristics of surgically proven mitral valve cleft in children.

A retrospective analysis was performed on the surgical results and 2D-TTE data of patients with mitral valve cleft confirmed by surgery at the Pediatric Cardiovascular Center, Beijing Anzhen Hospital, Capital Medical University from July 2009 to May 2022, and the echocardioimagedata characteristics and pathogenesis of mitral valve cleft were summarized. According to the mitral valve nomenclature proposed by Carpentier, multi-section and multi-angle scanning methods combined with color Doppler imaging (CDFI) were used to locate mitral valve cleft, record the degree of its involvement, and evaluate the degree of regurgitation. The changes in the degree of mitral regurgitation between before and after surgery were statistically compared by the corrected χ² test. The diagnostic accuracy of echocardiography was calculated by comparing with surgical findings.

Among the 108 patients included, 47 had isolated mitral valve cleft and the remaining 61 had mitral valve cleft complicated with cardiac malformation. Surgical results showed that incomplete mitral valve cleft was most common in the A2 region of the anterior mitral valve leaflet, while the incomplete posterior mitral valve leaflet cleft was most common in the P2 region. The diagnostic accuracy of 2D-TTE for anterior mitral valve leaflet cleft was high in the A2 (76.9%, 40/52) and A2-A3 regions (62.5%, 5/8). The diagnostic accuracy of 2D-TTE for posterior mitral valve leaflet cleft and multiple small clefts was very low at only 2.5% (1/40), and the total diagnostic accuracy for mitral valve cleft (anterior and posterior leaflets) was 41.7% (45/108). Severe or moderate mitral regurgitation accounted for 63.8% (69/108) and 26.9% (29/108) of patients before surgery. After mitral valve plasty (MVP), the mitral regurgitation was significantly improved. There were no severe mitral regurgitation cases and only 3.7% (4/108) of patients had moderate mitral regurgitation. There were statistical differences in the improvement of mitral regurgitation between groups with different degrees of mitral regurgitation both before and after MVP (χ²=8.158 and 41.173; P=0.004 and <0.001, respectively), and mitral regurgitation was significantly improved after operation. Characteristic sonoimagedataal findings included: (1) the anterior mitral valve echo was interrupted with a "fissure" shape on the horizontal short axis section of the mitral valve; (2) the position and width of anterior mitral valve leaflet cleft could be displayed on the horizontal short axis section of the mitral valve, but the shape of cleft could not be displayed; (3) the extent and degree of anterior mitral valve leaflet cleft involvement could be showed on the parasternal left ventricle long axis section; (4) the anterior mitral valve leaflet cleft was easy to be showed in the A2 region and between the A2 and A3 regions, but the posterior mitral valve leaflet cleft was difficult to be showed; (5) color Doppler flow imaging (CDFI) showed different degrees of mitral regurgitation signals in the systole; (6) the anterior mitral valve leaflet cleft tended to be complicated with mitral valve prolapse and leaflet thickening and crimp; and (7) other cardiac malformations could be combined.

Mitral valve cleft in children is easy to be complicated with other intracardial malformations. The main 2D-TTE feature of mitral valve cleft in children is that the mitral valve leaflet echo is interrupted, showing a "crack" shape, and the mitral regurgitation signal originates from the crack. 2D-TTE is more accurate in diagnosing anterior mitral valve leaflet cleft in the A2 and A2-A3 regions, and is easy to miss posterior and small anterior mitral valve leaflet cleft. MVP can significantly improve mitral regurgitation.