INCIDENCE, SIGNIFICANCE, AND PHARMACOLOGICAL RESPONSES OF CATHETER-INDUCED MECHANICAL TRAUMA IN PATIENTS RECEIVING RADIOFREQUENCY ABLATION FOR SUPRAVENTRICULAR TACHYCARDIA

Background Catheter-induced mechanical trauma is unfavorable during el ectrophysiological study. However, its incidence, significance, and ph armacological responses in patients receiving radiofrequency ablation for supraventricular tachycardia have not been investigated. Methods a nd Results A prospective study was performed in 666 consecutive patien ts with documented, symptomatic supraventricular tachycardia. All had been referred for electrophysiological study and radiofrequency ablati on. Catheter-induced mechanical trauma was defined by either disappear ance of or change in preexcitation pattern induced by the electrode ca theters or noninducibility of tachycardia after the electrode catheter -induced termination of tachycardia, confirmed by electrophysiological study. Adenosine, isoproterenol, and atropine were serially administe red 1 hour after the mechanical trauma to study pharmacological respon se. ''Rescue'' radiofrequency ablation was defined as delivery of radi ofrequency energy just at the presumed ablation site immediately after the mechanical trauma. Of the 666 patients, 254 had atrioventricular (AV) nodal reentrant tachycardia, 367 patients had accessory pathways, 30 patients had atrial tachycardia, and 15 had atrial flutter. Cathet er-induced mechanical trauma occurred in 17 patients (2.6%): 4 patient s had AV nodal reentrant tachycardia, 9 had accessory pathways, and 4 had atrial tachycardia. Five patients had such episodes during the pla cement of electrode catheters and 12, during mapping and ablation proc edures. Of the 4 patients with AV nodal reentrant tachycardia, 3 had m echanical trauma on the retrograde fast pathway and 1, on the antegrad e slow pathway. In the 9 patients with accessory pathways, those pathw ays were located in the left free wall in 4 patients, right free wall in 1, right posteroseptum in 1, and right anteroseptum in 3. Atrial ta chycardia was more easily traumatized than AV nodal reentrant tachycar dia (P<.01) and than accessory pathways (P<.01). The clinical courses of mechanical trauma were variable: 1 patient had spontaneous recovery within 1 week, 5 patients had recurrence of tachycardia within 3 mont hs, and the rest have been free of tachycardia from 3 to 35 months. Th e recurrence rate was higher in patients with mechanical trauma than i n those without (33.3% versus 3.5%, P<.0001) despite rescue radiofrequ ency ablation given in 7 patients. Pharmacological agents were general ly unable to revive the traumatized tissues, and recurrence was unpred ictable. Conclusions Catheter-induced mechanical trauma was not common in patients receiving radiofrequency ablation for supraventricular ta chycardia. Their clinical courses were variable, and pharmacological m anipulation offered little assistance. More than half of the patients had long-term cures. However, the recurrence rate was, on the whole, s ignificantly high despite rescue radiofrequency ablation. There is a n eed for great caution in the placement of electrode catheters in every patient during electrophysiological study and radiofrequency ablation .