Minimally invasive trans-mitral septal myectomy for diffuse-type hypertrophic obstructive cardiomyopathy

Despite excellent long-term results reported for a trans-aortic septal myectomy for hypertrophic obstructive cardiomyopathy (HOCM), surgery for patients with diffuse hypertrophy is very challenging. In addition, a left ventricular outflow obstruction is often aggravated by an abnormal mitral valve and subvalvular apparatus.

We performed video-assisted minimally invasive trans-mitral septal myectomy procedures in 3 patients with diffuse-type HOCM, who were highly symptomatic despite maximal medical therapy. Each had at least moderate mitral regurgitation (MR) due to systolic anterior motion (SAM). Using a right mini-thoracotomy, the anterior mitral leaflet was detached, through which an extended septal myectomy could easily be performed. Abnormal bridging chordae between the septum and papillary muscle (PM) were divided, then anterior mitral leaflet continuity was restored with direct closure or augmentation using a glutaraldehyde-treated autologous pericardium. A PM reorientation procedure was performed in 1 case in which both PMs were approximated and sutured onto the posterior ventricular wall.

The postoperative course was uneventful in all patients, with marked improvement of symptoms in each. The peak ventricular outflow gradient decreased from 134 ± 40 to 23 ± 5 mmHg with significantly diminished SAM, especially in the patient who underwent the PM reorientation procedure. During a mean follow-up period of 42 ± 14 months, no MR has been detected in any case.

We believe that a minimally invasive trans-mitral septal myectomy is preferable for HOCM-patients with diffuse hypertrophy and mitral valve abnormality. Aggressive PM reorientation may also be useful for those with an abnormal PM orientation.