Download parasympathomimetic stimulation provokes vagally

PARASYMPATHOMIMETIC STIMULATION PROVOKES VAGALLY
MEDIATED PREMATURE VENTRICULAR CONTRACTIONS DURING
ELECTROPHYSIOLOGIC STUDY AND ABLATION
Kassenberg W, vd Heijden J, Hassink R, Doevendans P, Loh P. Department of Cardiology, Heart Lung
Center Utrecht, University Medical Center, Heidelberglaan 100, P.O. Box 85500, 3508 GA Utrecht,
The Netherlands.
Background
During electrophysiologic study (EPS) and radiofrequency (RF) ablation of mainly vagally mediated,
symptomatic premature ventricular contractions (PVC), ectopy may be absent due to stress induced
sympathetic stimulation or sedative drugs. We hypothesized that pharmacological stimulation of the
parasympathetic nervous system may provoke PVC’s.
Methods and results
We included three female patients with symptomatic PVC’s with left bundle branch block morphology
and vertical axis (right ventricular outflow tract (RVOT) origin). Previous ablation attempts failed
because PVC’s were absent and could not be provoked by sympathetic stimulation (isoprenaline),
atropine, adenosine, esmolol or sedation. Antiarrhythmic drugs were withheld 5 half-lives before the
procedure. Procedures were conducted under general anaesthesia or Propofol sedation. A
parasympathomimetic drug (Neostigmine, 1 mg) was administered intravenously (iv). After
7-15 minutes clinical PVC’s appeared (figure 1) and enabled activation mapping and successful ablation
in all 3 patients. Earliest activation during mapping was found postero-lateral, septal and anterior in the
RVOT. Early signals were found up to 40ms before QRS. Post ablation provocation with Neostigmine
was done in two patients. No PVC’s were induced. One patient received the maximum dose pre
ablation. Follow up of 4 and 21 months respectively showed no recurrence of ectopic contractions
on Holter monitoring in 2 patients. One patient had recurrence of ventricular ectopy with other
morphologies. All three procedures were free of complications.
Conclusion
In electrophysiological study and ablation procedures where mainly vagally mediated PVC’s are
non-inducible due to sympathetic stimulation (stress) and/or sedative drugs, stimulation of the
parasympathetic nervous system with Neostigmine provokes ventricular ectopy and enables activation
mapping and ablation.