Intravascular parasympathetic cardiac nerve stimulation prevents ventricular arrhythmias during acute myocardial ischemia

Although previous animal studies clearly demonstrated antiarrhythmic effects of vagal stimulation during acute myocardial ischemia, highly invasive nature of vagal stimulation limited its clinical use. Recently, intravascular parasympathetic cardiac nerve stimulation (IPS) has emerged as a novel approach to the cardiac autonomic nervous system. We hypothesized that IPS might prevent ventricular arrhythmias during acute myocardial ischemia. Methods: The IPS (36 V, 10 Hz) was performed in superior vena cava using an expandable electrode-basket catheter. In 18 open-chest dogs, left anterior descending coronary artery ligation was performed without IPS (control group, n = 6), with IPS (IPS group, n = 6) and with IPS and right atrial pacing at 180/min (IPS+P group, n = 6). The ECGs were monitored for 60 min. The incidence and severity of ventricular arrhythmias were analyzed. Results: The IPS significantly decreased the frequency of premature ventricular contractions (control group: 9.1 plusmn 4.6 /min, IPS group: 0.2 plusmn 0.4 /min, IPS+P group: 10.6 plusmn 4.2 /min; p < 0.05). The frequency of ventricular tachycardia was lower in IPS group (0 plusmn 0 /min) than in control group (0.15 plusmn 0.18 /min, p < 0.05) and than in IPS+P group (0.17 plusmn 0.12 /min, p < 0.05). The incidence of ventricular fibrillation was lower in IPS group (0%) than in control group (33.3%) and than in IPS+P group (33.3%). Conclusions: The IPS suppressed ventricular arrhythmias during acute ischemia mainly through its bradycardiac effect. In addition to the conventional pharmacological antiarrhythmic therapy, IPS might be an alternative tool to control ventricular arrhythmias especially in patients with refractory arrhythmias to pharmacological therapy