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

Idiopathic right ventricular outflow tract (RVOT) tachycardia is prone to o ccur when sympathetic nervous activity increases. The effects of catheter a blation on the arrhythmia may be modified by changes in the sympathovagal b alance induced by the ablation, In 8 patients with RVOT tachycardia, analys es 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 (00.00-06.00h ) were analyzed. MSSD and pNN50 were increased along with a decrease in the frequency of ventricular arrhythmias at both POST1 and POST2 after success ful 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 patie nts. 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, Af ter successful catheter ablation of the RVOT tachycardia, sympathetic nervo us activity was decreased and parasympathetic nervous activity was increase d along with decrease in the frequency of ventricular arrhythmias. The pres ence of ventricular tachyarrhythmia could, therefore, elicit sympathetic pr edominance and consequently modify arrhythmogenesis.