OBJECTIVETo summarize the experience of ventricular septal myectomy (modified Morrow procedure) in patients with hypertrophic obstructive cardiomyopathy (HOCM).

METHODSFrom June 2003 to March 2011, 38 patients (26 male and 12 female) with HOCM underwent modified Morrow procedure. The mean age was 36.3 years (ranging from 18 to 64 years). The diagnosis was made by echocardiography and spiral CT. The mean systolic gradient between the left ventricle and the aorta from transthoracic echocardiography (TTE) was (89±31) mmHg (ranging from 50 to 184 mmHg, 1 mmHg=0.133 kPa) before operation. There was moderate or severe systolic anterior motion (SAM) in 38 cases and mitral regurgitation in 29 cases. Ventricular septal myectomy with modified Morrow procedure was performed in all 38 cases. TEE was used intraoperatively to evaluate the results of the surgical procedures. After 1 to 2 weeks of operation, TTE was performed to evaluate the effect of operation. All patients were followed up with TTE after operation.

RESULTSAll patients were discharged without complications. Intraoperative TEE showed that the mean systolic gradient between the left ventricle and the aorta was decreased from (95±36) mmHg before procedures to (14±11) mmHg after operation (t=13.265, P=0.000), and the thickness of ventricular septum was decreased from (28±8) mm to (12±3) mm (t=11.656, P=0.000). TTE showed that the mean systolic gradient between the left ventricle and the aorta was decreased from (89±31) mmHg preoperatively to (18±13) mmHg (t=12.729, P=0.000) in 1 to 2 weeks after operation. Mitral regurgitation and SAM were significantly improved or disappeared (t=7.930, t=5.213, both P=0.000). During the follow-up, all patients promptly became completely asymptomatic or complained of mild effort dyspnea only and syncope was abolished, and TTE showed that the pressure gradient was kept on the postoperative level or slightly decreased (P=0.494).

CONCLUSIONSVentricular septal myectomy with modified Morrow procedure is a mostly effective method for patients with HOCM. Good surgical exposure and the hypertrophied septum thoroughly excised are paramount for successful surgery.