COMPARATIVE ATRIOVENTRICULAR NODE PROPERTIES AFTER RADIOFREQUENCY ABLATION AND OPERATIVE THERAPY OF ATRIOVENTRICULAR NODE REENTRY

The anatomical substrate for atrioventricular (AV) node reentry is unc lear. To gain insights into the mechanism of cure of AV node reentry b y nonpharmacological techniques, we compared AV node properties in 53 patients undergoing operative therapy (perinodal dissection) and 43 un dergoing radiofrequency ablation (28 posterior approach, 15 anterior a pproach). Anterior radiofrequency ablation was associated with signifi cant AH prolongation (62 +/- 18 msec vs 136 +/- 64 msec, P < 0.0001), loss of ''fast'' pathway physiology, and no change in the anterograde refractory period of the AV node (273 +/- 24 msec vs 268 +/- 28 msec, P = NS). Posterior radiofrequency ablation did not change the AH inter val (67 +/- 17 msec vs 68 +/- 17 msec, P = NS), prolonged AV node effe ctive refractory period (275 +/- 48 msec vs 320 +/- 55 msec, P < 0.000 1), and was associated with loss of ''slow pathway'' physiology. Opera tive treatment prolonged the AH interval (66 +/- 18 msec vs 83 +/- 37 msec, P < 0.0001) and the AV node effective refractory period (264 +/- 52 msec vs 364 +/- 112 msec, P < 0.0001), and affected dual pathway p hysiology inconsistently. These data support the view that the ''fast' ' and ''slow'' pathways are distinct perinodal entities that can be se lectively ablated. The operative approach causes more diffuse and vari able injury to the AV node region.