High-Resolution Mapping of Postinfarction Reentrant Ventricular Tachycardia: Electrophysiological Characterization of the Circuit

Elad Anter*, Cory M. Tschabrunn, Alfred E. Buxton, Mark E. Josephson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Background: In vivo description of ventricular tachycardia (VT) circuits is limited by insufficient spatiotemporal resolution. We used a novel high-resolution mapping technology to characterize the electrophysiological properties of the postinfarction reentrant VT circuit. Methods: In 15 swine, myocardial infarction was induced by left anterior descending artery balloon occlusion. Animals were studied 6 to 8 weeks after myocardial infarction. Activation mapping of VTs was performed by using the Rhythmia mapping system. Activation time was based on a combination of bipolar and unipolar electrograms. The response to overdrive pacing from different zones of the circuit was examined. Results: A total of 56 monomorphic VTs were induced (3.8±2.1 per animal). Among these, 21 (37.5%) were hemodynamically stable and allowed mapping of the circuit. Isthmuses were 16.4±7.2 mm long and 7.4±2.8 mm wide. Conduction velocities were slowest at the inward curvature into the isthmus entrance (0.28±0.2 m/s), slightly faster at the outward curvature exit (0.40±0.3 m/s) and nearly normal at the central isthmus (0.62±0.2 m/s). In 3 animals, 2 VT morphologies with opposite axes sharing the same isthmus were mapped. Conduction velocities within the shared isthmus were dependent on the activation vector, consistently slower at the proximal curvature. Overdrive pacing from isthmus sites determined by activation mapping was consistent with entrainment criteria for isthmus. However, dimensions of the isthmus defined by entrainment exceeded dimensions of the isthmus measured by activation mapping by 32±18%. Conclusions: In postinfarction reentrant VT, conduction velocities are slowest at the proximal and distal curvatures. Entrainment mapping overestimates the true size of the isthmus. High-resolution activation mapping of VT may better guide ablation therapy.

Original languageEnglish
Pages (from-to)314-327
Number of pages14
JournalCirculation
Volume134
Issue number4
DOIs
StatePublished - 26 Jul 2016
Externally publishedYes

Funding

FundersFunder number
National Institutes of HealthR21HL127650
National Heart, Lung, and Blood InstituteR01HL129185
Boston Scientific Corporation

    Keywords

    • cardiac ablation
    • electrophysiology
    • intracardiac electrograms
    • mapping
    • myocardial infarction
    • ventricular tachycardia

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