CASE PRESENTATION
A 15-year-old girl was referred to our hospital with a history of chest pain, shortness of breath, and presyncope. She had been suffering from chest pain since the age of 12 and had a history of frequent dizziness. The chest pain was atypical and had some non-specific features. She had no medical history and no family history of heart disease. On physical examination, her blood pressure was normal (110/60 mmHg) and cardiac auscultation revealed a grade 2/6 systolic murmur at the left sternal border. Laboratory tests revealed normal blood count, renal and liver function tests. Her ECG demonstrated right axis deviation, incomplete right bundle branch block and right ventricular dilation.
Two-dimensional transthoracic echocardiography (2D-TTE) revealed normal left ventricular size, mild left ventricular hypertrophy and systolic function. Left ventricular outflow tract showed a large, mobile, filamentous abnormal structure. The chordae of the anterior mitral leaflet were intact. This tissue was found to prolapse into the LVOT during systole. The morphology was suggestive of an AMVT. In addition, TTE and TEE showed a wide secundum-type ASD with moderate dilatation of the right heart chambers and mild aortic regurgitation (AR) (Fig 1).
However, the 2D-TTE images were not perfect and therefore three-dimensional transesophageal echocardiography (3D-TEE) was planned. Three-dimensional TEE provided anatomical information about other cardiac structures. Transesophageal echocardiography showed that the AMVT was attached to the ventricular portion of the anterior mitral valve leaflet, which prolapsed in and out of the LVOT, causing only mild LVOT obstruction (mean gradient 42 mmHg) and mild AR (Fig 2).
In this case, the physicians opted for surgical excision of the AMVT because of the development of LVOT obstruction and AR. In addition, the patient was not suitable for ASD transcatheter closure because of the flail atrial septum and insufficient aortic rim. Excision of the AMVT was easily achieved by aortotomy without the need for a left atriotomy. The ostium secundum ASD was closed with a pericardial patch. In the postoperative period, there was no LVOT obstruction and AR.