Emergency trans-mitral septal myectomy with resection of abnormal papillary muscles

This patient was a septuagenarian female with a past medical history of hypertrophic cardiomyopathy with systolic anterior motion and moderate mitral regurgitation. Preprocedural transoesophageal echocardiography did not show any abnormal papillary muscle. An elective alcohol septal ablation was performed. During alcohol septal ablation at the catheterization laboratory, the patient developed acute cardiogenic shock with pulmonary oedema that required intubation. Transoesophageal echocardiography showed worsening obstruction of the left ventricular outflow tract due to swelling of the septum with severe mitral regurgitation. Emergency surgery via a median sternotomy revealed anomalous papillary muscles with direct insertion into the body of the leaflet and attachment to the free edge of the anterior leaflet (Mayo classification type II). The anterior leaflet and abnormal papillary muscles were resected, followed by septal myectomy through the same exposure. The mitral valve was replaced with a 29-mm tissue valve. Postoperative transoesophageal echocardiography confirmed the release of the left ventricular outflow tract obstruction. The patient's postoperative course was uneventful. This case highlights a rare but serious complication after alcohol septal ablation. Whereas anomalous papillary muscle is one of the important mechanisms of left ventricular outflow tract obstruction, its diagnosis can be challenging in a subset of patients prior to surgical repair.