Antitachycardia Pacing at the His Bundle is Safer than Conventional
Right Ventricular Antitachycardia Pacing in a Canine Myocardial Ischemic
Injury Model
Abstract
Introduction: Antitachycardia pacing (ATP) is used to terminate
ventricular tachycardia (VT) by delivering rapid, low energy pacing to
the right ventricle (RV). Unfortunately, ATP is not effective against
all VT episodes and can result in adverse outcomes, such as VT
acceleration and degeneration into ventricular fibrillation (VF).
Improving ATP is therefore desirable. Our objective was to compare the
efficacy and safety of ATP delivered at the His bundle to traditional
ATP. Methods: Six dogs were anesthetized and pacing leads were implanted
in the RV and His bundle. The lateral anterior descending artery (LAD)
was occluded for 2 hours to create an ischemic injury. In a study 4-7
days later, a 128-electrode sock was placed snugly around the ventricles
and VT was induced using rapid pacing. ATP was delivered from either the
His bundle or RV lead, then attempted at the other location if
unsuccessful. Success rates and instances of VT acceleration and
degeneration into VF were calculated. Results: We induced 83 runs of VT
and attempted ATP 128 times. RV ATP was successful in 36% of attempts;
His ATP was successful in 38% of attempts. RV ATP resulted in
significantly more adverse outcomes. RV and His ATP induced VT
acceleration in 9% and 3% of trains respectively, and induced
degeneration into VF in 5% and 1% of trains, respectively. Conclusion:
His bundle ATP is safer, but not significantly more effective, than RV
ATP.