[Hypertrophic Obstructive Cardiomyopathy Associated with Apical-basal Muscle Bundle Treated by Extended Septal Myectomy and Surgical Excision of a Muscle Bundle:Report of a Case].

A 74-year-old woman was diagnosed with obstructive hypertrophic cardiomyopathy and symptoms of heart failure. Transthoracic echocardiography and other imaging examinations revealed an apical-basal muscle bundle caused by a left ventricular outflow tract(LVOT) obstruction. The peak velocity was 6.1 m/s, recorded during the Valsalva maneuver, and mitral regurgitation progressed from trivial to moderate. The course of operative treatment consisted of surgical intervention in the mitral valve. The LVOT revealed an apical-basal muscle bundle, approximately 6 mm in diameter;however, this was excluded. Extended septal myectomy and intraoperative transesophageal echocardiography were performed, the latter to verify the systolic anterior motion of the mitral valve;however, mitral regurgitation was not detected. The post-operative peak velocity improved to 2.5 m/s. In conclusion, surgical treatment of obstructive hypertrophic cardiomyopathy and LVOT obstruction associated with an apical-basal muscle bundle was performed with accurate diagnosis, thus avoiding valvular surgery.