Preserved Autonomic Modulation of the Sinus and Atrioventricular Nodes Following Posteroseptal Ablation for Treatment of Atrioventricular Nodal Reentrant Tachycardia

INTRODUCTION: Following radiofrequency catheter ablation of AV nodal reentrant tachycardia (AVNRT), inappropriate sinus tachycardia may occur, possibly due to damage to autonomic cardiac nerve fibers. Furthermore, inducibility of AVNRT is often critically dependent on the autonomic balance. We investigated whether successful ablation of AVNRT is associated with an alteration of autonomic 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-quality nighttime ECG recordings of 11 patients before and after radiofrequency 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 node (PR). Before ablation, LF/HF(PP) was 3.2 and nHF(PP) was 0.3 in the sinus node. For the AV node, LF/HF(PR) was 1.2 and nHF(PR) was 0.5. Following ablation, LF/HF(PP) (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/HF(PR) (1.2) and nHF(PR) (0.5) remained unchanged. CONCLUSION: Our results indicate that autonomic control of the sinus and AV nodes is preserved following successful radiofrequency ablation of AVNRT. The effects of posteroseptal radiofrequency current application are not necessarily mediated by changes in the autonomic input to the AV node.