Alcohol septal ablation versus surgical septal myectomy: comparison of effects on atrioventricular conduction tissue
Deepak R Talreja1, Rick A Nishimura, William D Edwards
1Mayo Graduate School of Medicine, Mayo Foundation, 200 First Street SW, Rochester, MN 55905, USA.
Insights
Septal reduction therapies for hypertrophic cardiomyopathy (HCM) have different effects on the heart's conduction system. Alcohol septal ablation primarily impacts the right bundle branch, while surgical myectomy affects the left bundle branch, influencing heart block risks.
Area of Science:
- Cardiology
- Cardiac Electrophysiology
- Interventional Cardiology
Background:
- Heart block is a known complication of septal reduction therapies for hypertrophic cardiomyopathy (HCM).
- Understanding the distinct effects of catheter-based and surgical interventions on the cardiac conduction system is crucial for patient management.
Purpose of the Study:
- To evaluate and compare the impact of percutaneous alcohol septal ablation and surgical septal myectomy on the cardiac conduction system in patients with HCM.
Main Methods:
- Retrospective review of electrocardiograms and postoperative outcomes for patients undergoing alcohol septal ablation or surgical myectomy.
- Data collected from Mayo Clinic between 1999 and 2003.
Main Results:
- Alcohol septal ablation (n=58) resulted in 36% developing right bundle branch block and 12% complete heart block requiring pacing.
- Surgical septal myectomy (n=117) led to 40% developing left bundle branch block and 3% complete heart block requiring pacing.
- Pre-existing bundle branch blocks influenced the type of heart block post-procedure.
Conclusions:
- Percutaneous alcohol septal ablation targets basal mid-septum and right bundle tissue, causing transmural infarction.
- Surgical myectomy affects the basal anterior septum and left bundle tissue, impacting the endocardial portion.
- These findings aid in identifying patients at higher risk for complete heart block following septal reduction procedures for HCM.
Objectives:
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.
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