Incidence, significance, and pharmacological responses of catheter-induced mechanical trauma in patients receiving radiofrequency ablation for supraventricular tachycardia.
Authors: Chiang C E , Chen S A , Wu T J , Yang C J , Cheng C C , Wang S P , Chiang B N , Chang M S 
Published: June 2012

BACKGROUND
Catheter-induced mechanical trauma is unfavorable during electrophysiological study. However, its incidence, significance, and pharmacological responses in patients receiving radiofrequency ablation for supraventricular tachycardia have not been investigated.

METHODS AND RESULTS
A prospective study was performed in 666 consecutive patients with documented, symptomatic supraventricular tachycardia. All had been referred for electrophysiological study and radiofrequency ablation. Catheter-induced mechanical trauma was defined by either disappearance of or change in preexcitation pattern induced by the electrode catheters or noninducibility of tachycardia after the electrode catheter-induced termination of tachycardia, confirmed by electrophysiological study. Adenosine, isoproterenol, and atropine were serially administered 1 hour after the mechanical trauma to study pharmacological response. "Rescue" radiofrequency ablation was defined as delivery of radiofrequency 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. Catheter-induced mechanical trauma occurred in 17 patients (2.6%): 4 patients had AV nodal reentrant tachycardia, 9 had accessory pathways, and 4 had atrial tachycardia. Five patients had such episodes during the placement of electrode catheters and 12, during mapping and ablation procedures. Of the 4 patients with AV nodal reentrant tachycardia, 3 had mechanical trauma on the retrograde fast pathway and 1, on the antegrade slow pathway. In the 9 patients with accessory pathways, those pathways 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 tachycardia was more easily traumatized than AV nodal reentrant tachycardia (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 months, and the rest have been free of tachycardia from 3 to 35 months. The recurrence rate was higher in patients with mechanical trauma than in those without (33.3% versus 3.5%, P < .0001) despite rescue radiofrequency ablation given in 7 patients. Pharmacological agents were generally unable to revive the traumatized tissues, and recurrence was unpredictable.

CONCLUSIONS
Catheter-induced mechanical trauma was not common in patients receiving radiofrequency ablation for supraventricular tachycardia. Their clinical courses were variable, and pharmacological manipulation offered little assistance. More than half of the patients had long-term cures. However, the recurrence rate was, on the whole, significantly high despite rescue radiofrequency ablation. There is a need for great caution in the placement of electrode catheters in every patient during electrophysiological study and radiofrequency ablation.