Intracardiac stimulation of human parasympathetic nerve fibers induces negative dromotropic effects: implication with the lesions of radiofrequency catheter ablation.
BACKGROUND
The dromotropic effects of intracardiac parasympathetic nerve stimulation have not been well studied; furthermore, the effects of radiofrequency ablation lesions on parasympathetic nerve stimulation are not clear.


RESULTS
Group I: intracardiac electrical stimulation in the right posteroseptal and anteroseptal areas under different stimulation strengths; group II: intracardiac electrical stimulation before and 10 minutes after intravenous propranolol; group III: intracardiac electrical stimulation before and 5 minutes after intravenous atropine. Among the 10 patients with AV nodal reentrant tachycardia (group IV) and the 10 patients with atrial flutter (group V), atrial fibrillation was induced before and after successful ablation, and intracardiac electrical stimulation in the right posteroseptal area was performed before and after successful ablation. The maximal response and complete decay of the response occurred within 2 to 6 seconds of initiation or termination of parasympathetic nerve stimulation. This negative dromotropic effect disappeared after atropine was administered, but not after propranolol. After successful ablation, parasympathetic stimulation still induced negative dromotropic effects.


CONCLUSIONS
Electrical stimulation of parasympathetic nerve fibers near the posteroseptal and anteroseptal areas could induce a negative dromotropic effect, and this effect was preserved after successful radiofrequency ablation of slow pathway and isthmus conduction.
Chen
S A
SA
Department of Medicine, National Yang-Ming University, School of Medicine, Taiwan, Republic of China.
Chiang
C E
CE
Tai
C T
CT
Wen
Z C
ZC
Lee
S H
SH
Chiou
C W
CW
Ding
Y A
YA
Chang
M S
MS
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D001283:Atrioventricular Node / Q000502:physiology; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004562:Electrocardiography; D006321:Heart / Q000187:drug effects / Q000294:innervation*; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D017777:Parasympathetic Fibers, Postganglionic / Q000187:drug effects / Q000502:physiology*; D011433:Propranolol / Q000494:pharmacology; D013614:Tachycardia, Paroxysmal / Q000188:drug therapy / Q000503:physiopathology
D000319:Adrenergic beta-Antagonists; D011433:Propranolol