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),

Rate Control of Atrial Arrhythmias Can Be Achieved by Selective Cardiac Neurostimulation

Introduction: Atrial arrhythmias (AA) occur in up to 40% of patients recovering from open-heart surgery (OHS). Pharmacologic treatment has been the main strategy used for the control of post-operative AA, but is associated with hypotension, pro-arrhythmia and myocardial dysfunction. There is a need for a reversible, modulated solution to rate control. We demonstrated the efficacy of vagal stimulation at inferior right fat pad (FP) to slow the ventricular response (VR) of atrial fibrillation (AF) and junctional ectopic tachycardia (JET). We hypothesized that the VR response to AA could be improved by alterations in 1) the site of stimulation (anterior right FP vs. inferior right FP), 2) site within the two FP regions tested, and 3) whether there was a relationship between stimulation voltage (V) and electrophysiologic effect. Methods: Eight mongrel dogs, age 8.7 ± 3.9 months and weighing 21.5 ± 2.5 kg, underwent open heart surgery replicating Tetralogy of Fallot repair. Stimulation of the anterior right (AR) and inferior right (IR) fat pad was used to control the VR of AF and JET. A 7-pole electrode was sutured to the AR and IR FP and used to deliver stimulation therapy. Tested parameters included: 1) FP site, 2) stimulation pole configuration, and 3) stimulation (1-25) V on the VR to AF and JET. Stimulation frequency was 30 Hz, and pulse width was 0.15 msec. Results: 1). The inferior right FP was more effective in slowing the VR response to AF (-0.43 ± 0.18 vs. -0.18 ± 0.11 %, p =0.03) and JET (-0.16 ± 0.06 vs. 0.0 ±0.0, p =0.06.) 2). Selective site stimulation within a FP region could augment the effect of stimulation during AF (-0.48 ± 0.21 (maximum effect) vs. 0.0 ± 0.0 % (least effect), p=0.01). Stimulation of electrodes 2+3 produced the greatest reduction in HR with a maximum percent VR reduction of 34.8% 3). FP stimulation at increasing V demonstrated a voltage-dependent effect (-0.12 ± 0.19 (low V) vs. -0.63 ± 0.21 (high V) %, p=0.01)

IV sotalol use in pediatric and congenital heart patients: A multicenter registry study

Background There is limited information regarding the clinical use and effectiveness of IV sotalol in pediatric patients and patients with congenital heart disease, including those with severe myocardial dysfunction. A multicenter registry study was designed to evaluate the safety, efficacy, and dosing of IV sotalol. Methods and Results A total of 85 patients (age 1 day-36 years) received IV sotalol, of whom 45 (53%) had additional congenital cardiac diagnoses and 4 (5%) were greater than 18 years of age. In 79 patients (93%), IV sotalol was used to treat supraventricular tachycardia and 4 (5%) received it to treat ventricular arrhythmias. Severely decreased cardiac function by echocardiography was seen before IV sotalol in 7 (9%). The average dose was 1 mg/kg (range 0.5-1.8 mg/kg/dose) over a median of 60 minutes (range 30-300 minutes). Successful arrhythmia termination occurred in 31 patients (49%, 95% CI [37%-62%]) with improvement in rhythm control defined as rate reduction permitting overdrive pacing in an additional 18 patients (30%, 95% CI [19%-41%]). Eleven patients (16%) had significant QTc prolongation to \u3e465 milliseconds after the infusion, with 3 (4%) to \u3e500 milliseconds. There were 2 patients (2%) for whom the infusion was terminated early. Conclusions IV sotalol was safe and effective for termination or improvement of tachyarrhythmias in 79% of pediatric patients and patients with congenital heart disease, including those with severely depressed cardiac function. The most common dose, for both acute and maintenance dosing, was 1 mg/kg over ~60 minutes with rare serious complications