Alcohol septal ablation versus surgical septal myectomy: comparison of effects on atrioventricular conduction tissue.
OBJECTIVE
This study was designed to evaluate the effect of septal reduction therapies on the conduction system for patients with hypertrophic cardiomyopathy (HCM).


BACKGROUND
Heart block is a potential complication of both catheter-based and surgical procedures to relieve left ventricular outflow tract obstruction in HCM, but it is important to understand the different effects of these treatments on the conduction system.


METHODS
The electrocardiograms and postoperative course of patients who underwent percutaneous alcohol septal ablation or surgical myectomy at Mayo Clinic between 1999 and 2003 were reviewed.


RESULTS
For the 58 patients who underwent alcohol septal ablation, 21 (36%) developed right bundle branch block. Six patients (12%) developed complete heart block requiring permanent pacing, three of whom had left bundle branch block before the procedure. Among the 117 patients who underwent surgical septal myectomy, 47 (40%) developed left bundle branch block. Four patients (3%) developed heart block requiring permanent pacing after the procedure, three of whom had right bundle branch block preoperatively.


CONCLUSIONS
Percutaneous septal ablation selectively produces transmural infarction of the basal mid-septum and adjacent right bundle tissue, whereas surgical myectomy affects the endocardial portion of the basal anterior septum and adjacent left bundle tissue. These observations may help identify patients at risk for complete heart block after septal reduction procedures for HCM.
Talreja
Deepak R
DR
Mayo Graduate School of Medicine, Mayo Foundation, 200 First Street SW, Rochester, MN 55905, USA.
Nishimura
Rick A
RA
Edwards
William D
WD
Valeti
Uma S
US
Ommen
Steve R
SR
Tajik
A Jamil
AJ
Dearani
Joseph A
JA
Schaff
Hartzell V
HV
Holmes
David R
DR
D001283:Atrioventricular Node / Q000503:physiopathology*; D002037:Bundle-Branch Block / Q000139:chemically induced / Q000453:epidemiology / Q000209:etiology; D006328:Cardiac Catheterization; D002304:Cardiac Pacing, Artificial; D006348:Cardiac Surgical Procedures / Q000009:adverse effects; D002312:Cardiomyopathy, Hypertrophic / Q000188:drug therapy* / Q000503:physiopathology / Q000601:surgery*; D000431:Ethanol / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D006327:Heart Block / Q000139:chemically induced / Q000453:epidemiology / Q000209:etiology* / Q000628:therapy; D006346:Heart Septum / Q000187:drug effects* / Q000601:surgery*; D006801:Humans; D015994:Incidence; D011184:Postoperative Period
D000431:Ethanol