A Case of Mitral Valve Replacement for Left Ventricular Outflow Tract Obstruction due to Abnormal Papillary Muscle

Hiroyuki Seo

Hiromichi Fujii

Takanobu Aoyama and Yoshikado Sasako

(Department of Cardiovascular Surgery, Japan Community Health Care Organization, Osaka Hospital, Osaka, Japan）

A 72-year-old man, in whom hypertrophic cardiomyopathy（HCM）had been treated with medication for 4 years, complained of general fatigue and mild dyspnea on effort. Transthoracic and transesophageal echocardiography revealed diffuse left ventricular（LV）hypertrophy and LV obstruction from the mid-portion to the outflow tract with a peak pressure gradient of 94 mmHg. Additionally, anterior displacement of the abnormal, hypertrophied anterior papillary muscle（PM）and restricted motion of the anterior mitral leaflet, caused by the shortened chordae arising from the abnormal PM, were found. Furthermore, during the systolic phase, the abnormal, hypertrophied anterior PM was shifted to the septal side, causing LV obstruction with systolic anterior motion of the mitral leaflet. The diagnosis was HCM with LV obstruction due to abnormal PM. Mitral valve replacement（MVR）using a mechanical valve and excision of the abnormal PM was performed. His postoperative course was uneventful, and he was discharged on the 14th postoperative day. Postoperative echocardiography revealed no residual obstruction and no pressure gradient in the LV, indicating that complete release of the LV obstruction had been accomplished. In cases of HCM with LV obstruction due to an abnormal mitral subvalvular apparatus, transaortic septal myectomy may not always be an effective procedure. Therefore, we propose that MVR with excision of the PM should be considered one of the useful surgical procedures for such cases.

 

Jpn. J. Cardiovasc. Surg. 44:92-96（2015）

Keywords：hypertrophic cardiomyopathy;left ventricular outflow tract obstruction;abnormal papillary muscle;systolic anterior motion of the mitral leaflet;mitral valve replacement