Selective autonomic stimulation of the AV node fat pad to control rapid post-operative atrial arrhythmias.

Junctional ectopic tachycardia (JET) and atrial fibrillation (AF) occur in patients recovering from open-heart surgery (OHS). Pharmacologic treatment is used for the control of post-operative atrial arrhythmias (POAA), but is associated with side effects. There is a need for a reversible, modulated solution to rate control. We propose a non-pharmacologic technique that can modulate AV nodal conduction in a selective fashion. Ten mongrel dogs underwent OHS. Stimulation of the anterior right (AR) and inferior right (IR) fat pad (FP) was done using a 7-pole electrode. The IR was more effective in slowing the ventricular rate (VR) to AF (52 +/- 20 vs. 15 +/- 10%, p = 0.003) and JET (12 +/- 7 vs. 0 +/- 0%, p = 0.02). Selective site stimulation within a FP region could augment the effect of stimulation during AF (57 +/- 20% (maximum effect) vs. 0 +/- 0% (minimum effect), p<0.001). FP stimulation at increasing stimulation voltage (SV) demonstrated a voltage-dependent effect (8 +/- 14% (low V) vs. 63 +/- 17 (high V) %, p<0.001). In summary, AV node fat pad stimulation had a selective effect on the AV node by decreasing AV nodal conduction, with little effect on atrial activity.

Radiofrequency catheter ablation of intractable ventricular tachycardia in an infant following arterial switch operation.

A full-term male neonate presented with cyanosis upon delivery and was subsequently diagnosed with d-transposition of the great arteries, ventricular septal defect, and restrictive atrial septal defect. Following initiation of intravenous prostaglandins and balloon atrial septostomy, an arterial switch operation was performed on day 3 of life. The postoperative course was complicated by intractable ventricular tachycardia that was refractory to lidocaine, amiodarone, esmolol, fosphenytoin, and mexiletine drug therapy. Ventricular tachycardia was suppressed with overdrive atrial pacing but recurred upon discontinuation. Seven weeks postoperatively, radiofrequency catheter ablation was performed due to hemodynamically compromising persistent ventricular tachycardia refractory to medical therapy. The ventricular tachycardia was localized to the inferior-lateral right ventricular outlet septum. The procedure was successful without complications or recurrence. Antiarrhythmics were discontinued after the ablation procedure. Seven days after the ablation, a different, slower fascicular rhythm was noted to compete with the infant's sinus rhythm. This was consistent with the preablation amiodarone having reached subtherapeutic levels given its very long half-life. The patient was restarted on oral beta blockers and amiodarone. The patient was subsequently discharged home in predominantly sinus rhythm with intermittent fascicular rhythm.