Interactions between paced wavefronts and monomorphic ventricular tachycardia: implications for antitachycardia...

Area of Science:

• Cardiac Electrophysiology
• Arrhythmia Mechanisms
• Optical Mapping Techniques

Background:

• Antitachycardia pacing (ATP) efficacy is determined by interactions between paced wavefronts and ventricular tachycardia (VT).
• Understanding these interactions is crucial for optimizing ATP strategies and preventing proarrhythmic events.

Purpose of the Study:

• To investigate the electrophysiological interactions between paced wavefronts and monomorphic VT using optical mapping.
• To assess the impact of single-site versus dual-site pacing on VT termination and induction of polymorphic VT.

Main Methods:

• Optical mapping of rabbit ventricular epicardium during monomorphic VT.
• Initiation of VT in cryoablated rabbit hearts with apical anchors.
• Application of single and dual-site pacing at varying percentages of VT cycle length.

Main Results:

• Abrupt VT termination occurred when the VT wavefront collided with the antidromic paced wavefront, and the orthodromic wavefront was blocked.
• Effective dual-site pacing simultaneously capturing both leads terminated VT immediately.
• Polymorphic VT was induced primarily by single-lead capture, leading to functional reentry.
• Wavefront separation was the critical differentiator between effective termination and polymorphic VT induction.

Conclusions:

• The spatial and temporal separation of antidromic and orthodromic wavefronts is critical for successful ATP.
• Ineffective wavefront separation during pacing can lead to functional reentry and polymorphic VT.
• These findings provide insights into mechanisms of VT termination and induction, relevant to implantable cardioverter-defibrillator (ICD) therapies.