Midventricular obstruction(MVO) is a rare subset of hypertrophic obstructive cardiomyopathy(HOCM), prone to cause worse prognosis and residual gradients after myectomy. Surgical methods about it are limited and previous studies reported the difficulties of complete resection for hypertrophied septum in mid-ventricle, especially for patients with small aortic annulus or long distance of obstruction. We describe transaortic extended myectomy to reach complete resection for MVO patients with satisfied outcomes.
We consider transaortic extended myectomy can be efficacious for MVO patients.
Forty patients with gradient≥30mmHg at midventricular level were identified from 427 HOCM patients in our surgical team, from Oct-2002 to Oct-2016, by one surgeon. Patients’ characteristics, echocardiography, MRI, surgical procedure and outcomes were measured and analyzed.
The average diameter of aortic annulus was 22.1±2.3mm(19-28mm), mean distance from caudal point of obstruction to aortic annulus was 55.6±6.4mm(40-66mm), appraised by echocardiography preoperatively. With transaortic extended myectomy, their maximum septal thickness dropped from 26.2±5.5 to 16.6±5.0mm, midventricular gradients from 53.0mmHg(IQR,36.5-80.0mmHg) to 10.5mmHg(IQR,7.0-22.0mmHg)(P<0.001). No traction related aortic regurgitation was detected postoperatively. with a follow-up of 23 months (IQR,5.3-29.8), Patients’ NYHA classifications were improved and the degrees of mitral valve regurgitation decreased with no SAM phenomenon. There was no early or late death in our study.
Transaortic extended myectomy is an accessible and useful surgery to mitigate obstruction for patients with MVO only or MVO combined with subaortic obstruction.
Fig: A: Obstruction at subaortic and mid-ventricle under ECHO. B: Obstruction at mid-ventricle only. C/D: The corresponding resected muscle bar from A and B.