ATRIOVENTRICULAR NODAL REENTRY TACHYCARDIA IN PATIENTS WITH SINUS NODE DYSFUNCTION - ELECTROPHYSIOLOGIC CHARACTERISTICS, CLINICAL PRESENTATION, AND RESULTS OF SLOW PATHWAY ABLATION

AVNRT and Sinus Node Dysfunction. Introduction: Sinus node dysfunction (SND) is frequently associated with impaired AV conduction. This stud y investigated the electrophysiologic properties of dual AV nodal path ways in patients suffering from both SND and AV nodal reentrant tachyc ardia (AVNRT). Methods and Results: Two groups of patients with slow-f ast AVNRT underwent invasive electrophysiologic testing and catheter a blation of the slow pathway, Group a comprised 10 patients with SND (a ge 70 +/- 8 years), Group B included 10 age-matched patients without S ND (age 69 +/- 7 years; P = NS) who served as controls. Patients of gr oup ii exhibited prolongation of the anterograde Wenckebach cycle leng ths (WBCLs) of both the fast pathway (559 +/- 96 vs 361 +/- 38 msec; P < 0.01) and the slow pathway (409 +/- 57 vs 339 +/- 32 ms; P < 0.01), However, the delta between the WBCLs of the fast and the slow pathway s was larger in patients of group A (150 +/- 80 vs 22 +/- 20 msec; P < 0.01). Retrograde fast pathway conduction was well preserved with no difference in WBCLs (356 +/- 42 vs 330 +/- 47 msec; P = NS), Cycle len gths of AVNRT were longer in group A (468 +/- 46 vs 363 +/- 37 msec; P < 0.01). Clinically, all patients of group A. suffered from multiple episodes of AVNRT per week, which was not the case in any patient of g roup B (P < 0.01). Catheter ablation of the slow pathway eliminated AV NRT in all patients without complications. Conclusions: Patients with AVNRT and SND exhibit characteristic electrophysiologic alterations of both AV nodal pathways, Clinically, this results in significantly mor e frequent episodes of tachycardia, Slow pathway ablation appears to b e safe and effective in these patients.