探讨经手术证实的小儿二尖瓣裂的二维经胸超声心动图（2D-TTE）特征，以减少2D-TTE对二尖瓣裂的漏诊及误诊。

回顾性分析2009年7月至2022年5月首都医科大学附属北京安贞医院小儿心脏中心经手术证实的108例二尖瓣裂患儿的手术结果及2D-TTE图像资料，总结该病的2D-TTE特征、发病特点；根据Carpentier提出的二尖瓣命名法，采用多切面、多角度的扫查方法结合彩色多普勒成像（CDFI）对二尖瓣裂进行分区定位，记录瓣叶裂累及程度并评估反流程度，采用校正χ²检验比较手术前后二尖瓣反流程度变化，通过与手术所见对比超声心动图诊断的准确性。

108例二尖瓣裂患儿中，单纯性瓣叶裂47例，合并心内畸形者61例；手术显示二尖瓣前叶A2区不完全性裂最为多见（37例），后叶以P2区不完全性裂多见（10例），2D-TTE对前叶A2区及A2-A3区瓣叶裂诊断准确率较高，分别为76.9%（40/52）及62.5%（5/8），对后叶裂及前后叶多发细小裂隙诊断准确率极低，仅为2.5%（1/40），对二尖瓣裂（前叶及后叶）总的诊断准确率为41.7%（45/108）。术前二尖瓣大量、中量反流者占63.8%（69/108）、26.9%（29/108），二尖瓣成型术后反流明显改善，无大量反流的病例，中量反流病例仅有3.7%（4/108），术后二尖瓣反流均明显改善，手术前后不同程度反流组间比较，差异均具有统计学意义（P均<0.05）。二尖瓣裂2D-TTE特征：（1）左心室二尖瓣短轴切面显示二尖瓣前叶回声中断，呈“裂隙”状；（2）左心室二尖瓣短轴切面可明确前叶裂的位置和宽度，但不能明确前叶裂的形态；（3）胸骨旁左心室长轴切面可显示前叶裂累及的范围和程度；（4）二尖瓣前叶A2、A2-A3区的前叶裂容易显示，对后叶的裂隙显示困难；（5）CDFI显示收缩期源自二尖瓣裂处不同程度反流信号；（6）前叶裂容易合并二尖瓣瓣叶脱垂、增厚、卷曲；（7）可合并其他心内畸形。

小儿二尖瓣裂容易合并其他的心内畸形，2D-TTE主要特征为瓣叶回声中断，呈“裂隙”状，其二尖瓣反流信号源自裂隙处，2D-TTE对二尖瓣A2区、A2-A3区的前叶裂诊断准确率较高，对后叶裂及细小前叶裂容易漏诊，二尖瓣成形术可明显改善二尖瓣反流。

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.