Changes in autonomic nervous activity after catheter ablation of right ventricular outflow tract tachycardia

Idiopathic right ventricular outflow tract (RVOT) tachycardia is prone to occur when sympathetic nervous activity increases. The effects of catheter ablation on the arrhythmia may be modified by changes in the sympathovagal balance induced by the ablation. In 8 patients with RVOT tachycardia, analyses of heart rate variability (HRV) were performed before, early (1-3 days, POST1) and late (7-14 days, POST2) after the ablation. From 24-h ambulatory Holter monitoring, RR intervals of a 2-h period during sleep (00.00-06.00 h) were analyzed. MSSD and pNN50 were increased along with a decrease in the frequency of ventricular arrhythmias at both POST1 and POST2 after successful ablation. In contrast, high frequency power (HF) was increased, and low frequency power (LF) and LF/HF were decreased only at POST2 in the 8 patients. In 4 patients in whom the initial ablation had been unsuccessful, the indices of HRV did not change significantly after the unsuccessful ablation, but after successful ablation they changed as in the other 4 patients. After successful catheter ablation of the RVOT tachycardia, sympathetic nervous activity was decreased and parasympathetic nervous activity was increased along with decrease in the frequency of ventricular arrhythmias. The presence of ventricular tachyarrhythmia could, therefore, elicit sympathetic predominance and consequently modify arrhythmogenesis.