OBJECTIVETo analyze the clinical features, precaution and management of complete heart block (CHB) after transaortic extended septal myectomy operation (extended Morrow procedure) in patients with hypertrophic obstructive cardiomyopathy (HOCM).

METHODSFrom October 1996 to December 2011, 10[6 men; mean age (45.4 ± 15.8) years, range 13-60 years] out of 160 consecutive HOCM patients underwent extended Morrow procedure developed CHB postoperatively. Their clinical data were retrospectively analyzed. Baseline transthoracic echocardiography showed that the left ventricular outflow tract (LVOT) gradients was from 68 to 149 (105.1 ± 25.9) mm Hg (1 mm Hg = 0.133 kPa), ECG showed right bundle branch block in 5 patients and atrial fibrillation, atrial premature beats or ST-T segment changes in other 5 patients. Besides extended Morrow procedure, concomitant surgical procedures included mitral valve replacement (MVR) in 2 (2/10) and MVR plus coronary artery bypass grafting in another 2 (2/10) patients. Follow-up data were obtained by subsequent clinic visits in outpatient department and telephone interviews.

RESULTSThe in-hospital mortality was 20% (these two patients died of low cardiac output syndrome and multiple organs failure). Four patients underwent MVR simultaneously survived the operation. Postoperative echocardiography demonstrated a reduced LVOT gradient[(13.6 ± 9.7) mm Hg, P < 0.001]. Permanent pacemakers were implanted in all 8 survived patients at 6 days to 7 months after operation. No other severe complications were observed. During follow-up [from 4 to 72 (19.4 ± 22.1) months], there was no death, 1 patient readmitted to our center at 71 months post operation to change the pacemaker because of low voltage of previously implanted pacemaker. Physical capacity and quality of life improved significantly post operation in these 8 patients. The NYHA functional class remained at I-II post operation and during follow up.

CONCLUSIONSCHB is a severe complication after extended Morrow procedure for patients with HOCM and timely permanent pacemaker implantation is mandatory for patients with post procedure CHB.