Human model simulating right ventricular outflow tract tachycardia by high-frequency stimulation in the left pulmonary artery: autonomics and idiopathic ventricular arrhythmias.
BACKGROUND
Frequent monomorphic premature ventricular contractions (PVC) and/or ventricular tachycardia (VT) in patients with structurally normal heart usually arise from the right ventricular outflow tract (RVOT). An animal model simulating RVOT tachycardia by high-frequency stimulation (HFS) of the sympathetic input to the proximal pulmonary artery (PA) has been previously described. The aim of this study was to similarly induce RVOT tachycardia in humans.


METHODS
In 9 patients with no history of ventricular arrhythmias, a circumferential catheter was placed in the left, main, and proximal PA to contact the endovascular circumference of the PA. A 50-ms train of HFS (200 Hz/0.3 ms pulse duration), coupled to atrial pacing, was applied at each bipolar pair of the circumferential catheter. The coupling interval was adjusted so that the 50-ms train occurred during the ventricular refractory period.


RESULTS
In 6 out of 9 patients, HFS in the left PA during dobutamine infusion induced monomorphic PVCs and/or VT with left bundle branch block (LBBB) morphology and inferior axis at an average stimulation level of 12.5 +/- 2.7 V. HFS in the main PA and in the proximal PA did not induce any ventricular arrhythmias with the highest energy of 15 V in baseline state and during dobutamine infusion. HFS in the left PA was associated with hiccough in all patients.


CONCLUSIONS
Stimulation of the sympathetic input to the left PA during dobutamine infusion induces PVCs and/or VT exhibiting LBBB-morphology and inferior axis, closely simulating clinical RVOT tachycardia in humans.
Hasdemir
Can
C
Department of Cardiology, Ege University School of Medicine, Bornova, Izmir, Turkey. canrfca@yahoo.com
Alp
Alpay
A
Aydin
Mehmet
M
Can
Levent H
LH
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage; D000328:Adult; D002037:Bundle-Branch Block / Q000209:etiology* / Q000503:physiopathology; D002304:Cardiac Pacing, Artificial; D004280:Dobutamine / Q000008:administration & dosage; D004558:Electric Stimulation / Q000295:instrumentation; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac / Q000295:instrumentation; D004867:Equipment Design; D005260:Female; D006321:Heart / Q000294:innervation*; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000294:innervation*; D012032:Refractory Period, Electrophysiological; D015203:Reproducibility of Results; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D017180:Tachycardia, Ventricular / Q000209:etiology* / Q000503:physiopathology; D013997:Time Factors; D055815:Young Adult
D000318:Adrenergic beta-Agonists; D004280:Dobutamine