Histologic changes and arrhythmogenicity after discharge through transseptal catheter electrode

Area of Science:

• Cardiovascular Science
• Electrophysiology
• Medical Device Technology

Background:

• Ventricular tachycardia (VT) often originates in the intraventricular septum.
• Transseptal catheter ablation may improve treatment efficacy for septal VT.
• Evaluating the safety of transseptal electrode placement is crucial for clinical application.

Purpose of the Study:

• To assess the safety and efficacy of transseptal electrode placement for catheter ablation of ventricular tachycardia.
• To characterize the arrhythmogenic potential and histological outcomes of transseptal discharges.

Main Methods:

• High-energy capacitor discharges were delivered to an intracavitary cathode-anode pair across the interventricular septum in dogs.
• Arrhythmogenicity was evaluated by acute rhythm changes and programmed stimulation post-ablation.
• Histological examination of cardiac lesions was performed at various time points (20 min to 28 days).

Main Results:

• High energy discharges (100-200 J) induced lethal ventricular fibrillation.
• Lower energy discharges (30-100 J) created lesions without inducing sustained arrhythmias; defibrillation was successful.
• Lesions spanned the septum without perforation in 10/16 dogs, showing central hemorrhage and coagulation necrosis evolving over time.
• No induced ventricular tachycardia or fibrillation occurred after ablation procedures.

Conclusions:

• Transseptal electrode placement for catheter ablation is potentially safe at appropriate energy levels.
• The procedure can create effective septal lesions without inducing persistent arrhythmias.
• Further investigation into transseptal ablation techniques for septal VT is warranted.