[Anomalous insertion of the mitral valve. A rare form of subaortic obstruction in children]

Abstract

Among different anatomical causes of subaortic obstruction, anomalous attachment of the mitral valve on ventricular septum is one of the rarest. We report our experience with 4 such cases of subaortic obstruction. Their age at first observation ranged between 1 and 6 months. All patients had viscero-atrial situs solitus, levocardia and normal atrio-ventricular and ventriculo-arterial connections. None had associated cardiac septal defects. Cases with atrio-ventricular canal were excluded. All patients showed a systolic ejection murmur and electrocardiographic features of left ventricular hypertrophy; 3 presented congestive heart failure in the first 3 months of life. Diagnosis was made by 2D-echocardiography and cardiac catheterization in 3 patients and intraoperatively in 1. Only in the last 2 patients, correct diagnosis was made at the initial 2D-echocardiographic examination. Due to left ventricular hypertrophy, in the first 2 patients hypertrophic obstructive cardiomyopathy was originally suspected. One patient died intraoperatively during attempted transaortic resection of subaortic obstruction. Other 2 patients underwent left ventricle-aortic conduit implantation. Of these 2 patients, 1 died 3 months later for sepsis and the other was reoperated upon 3 years later for mitral valve replacement and conduit take-down, with good clinical result. The fourth patient is waiting for surgical intervention. Subaortic obstruction due to anomalous attachment of the mitral valve on ventricular septum may present with early congestive heart failure; the best diagnostic tool is 2D-echocardiography. Left ventricle-aortic conduit may represent a surgical alternative to transaortic resection.