PRESERVED AUTONOMIC MODULATION OF THE SINUS AND ATRIOVENTRICULAR NODES FOLLOWING POSTEROSEPTAL ABLATION FOR TREATMENT OF ATRIOVENTRICULAR NODAL REENTRANT TACHYCARDIA

Autonomic Control of the AV Node. Introduction: Following radiofrequen cy catheter ablation of AV nodal reentrant tachycardia (AVNRT), inappr opriate sinus tachycardia may occur, possibly due to damage to autonom ic cardiac nerve fibers. Furthermore, inducibility of AVNRT is often c ritically dependent on the autonomic balance. We investigated whether successful ablation of AVNRT is associated with an alteration of auton omic input to the sinus and AV nodes. Methods and Results: To estimate changes in the autonomic modulation of the sinus and AV nodes, power spectra of beat-to-beat PP and PR intervals were analyzed from high-qu ality nighttime ECG recordings of 11 patients before and after radiofr equency application. Normalized HF power (nHF) of PP and PR intervals was used as an index of efferent vagal modulation and the LF/HF ratio as an index of sympathovagal balance of the sinus node (PP) and AV nod e (PR). Before ablation, LF/HFPP was 3.2 and nHF(PP) was 0.3 in the si nus node. For the AV node, LF/HFPR was 1.2 and nHF(PR) was 0.5. Follow ing ablation, LF/HFPP (3.5) and nHF(PP) (0.3) of the PP intervals did not change. Similarly to the sinus node, there were no changes in the autonomic modulation of the AV node, as both LF/HFPR (1.2) and nHF(PR) (0.5) remained unchanged. Conclusion: Our results indicate that auton omic control of the sinus and AV nodes is preserved following successf ul radiofrequency ablation of AVNRT. The effects of posteroseptal radi ofrequency current application are not necessarily mediated by changes in the autonomic input to the AV node.