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Experimental Model Simulating Right Ventricular Outflow Tract Tachycardia: A Novel Technique to Initiate RVOT‐VT
Author(s) -
ZHOU JING,
SCHERLAG BENJAMIN J.,
YAMANASHI WILLIAM,
WU RICHARD,
HUANG YAN,
LAZZARA RALPH,
JACKMAN WARREN M.,
PO SUNNY S.
Publication year - 2006
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/j.1540-8167.2006.00509.x
Subject(s) - medicine , esmolol , cardiology , left bundle branch block , tachycardia , ventricular outflow tract , qrs complex , ventricular tachycardia , stimulation , right bundle branch block , refractory period , anesthesia , catheter ablation , electrocardiography , heart rate , ablation , heart failure , blood pressure
Objective: To simulate right ventricular outflow tract tachycardia (RVOT‐VT) in experimental animals. Background: The mechanism(s) whereby a discrete area of myocardium in the RVOT becomes arrhythmogenic remains unknown. Methods: In 13 dogs, a circular catheter was placed in the proximal pulmonary artery (PA) to contact the endovascular circumference of the PA. A 50‐msec train of high‐frequency stimulation (HFS, 200 Hz), coupled to atrial pacing, was applied at each bipolar pair of the circular catheter. The coupling interval was adjusted so that the 50‐msec train occurred during the ventricular refractory period, that is, the QRS complex, in order to prevent stimulation of the myocardial sleeve within the proximal PA. Results: In all dogs, HFS induced ventricular premature depolarizations and VTs with a left bundle branch block (LBBB) morphology and inferior axis (average 6.8 ± 1.6 V) . Earliest activation was consistently recorded from the proximal PA. Esmolol, a short‐acting beta‐blocker (1 mg/kg), was administered intravenously in 11 dogs. The inducible ventricular ectopy was abolished in 10 dogs (>12 V, P < 0.05) and the response to HFS was blunted in one dog (10–11 V). After 30 minutes, the response to HFS returned to pre‐esmolol levels. Conclusions: Stimulation of the sympathetic input to the proximal PA induces ventricular ectopy and VTs exhibiting a left bundle branch block morphology and inferior axis, closely simulating clinical RVOT‐VT. Beta‐blockade either abolishes or blunts this response, corroborating the sympathetic etiology in this model and in some clinical cases of RVOT tachycardias.