Slow AV Nodal Pathway Ablation Utilizing a Unique Temperature Controlled Radiofrequency Energy System

Abstract

Thirty-nine consecutive patients with symptomatic AV nodal reentrant tachycardia (AVNRT) underwent temperature guided slow AV nodal pathway ablation (group 1). Forty-three consecutive patients undergoing nontemperature guided slow AV nodal pathway ablation late in our experience compose the control population (group 2). Slow pathway ablation was achieved in all patients of both groups. The mean fluoroscopy and ablation times for group 1 were significantly shorter than for group 2 (26.1 +/- 14.9 vs 33.9 +/- 18.9 min, P < 0.05; 19.9 +/- 12.1 vs 30.9 +/- 23.3 min, P < or = 0.02). There were no episodes of coagulum formation in group 1, while there were 15 episodes (7.1% of energy applications) in group 2 (P = 0.0006) despite a significantly higher applied power in group 1 (53.4 +/- 25.1 vs 35.6 +/- 9.5W, P = 0.0001). Successful energy applications were associated with significantly higher temperatures than unsuccessful applications in group 1 (55.6 degrees +/- 5.8 degrees C vs. 52.9 degrees +/- 6.8 degrees C, P < or = 0.03). The minimum temperature required for successful ablation was 48 degrees C for two patients (5%) and was > or = 50 degrees C for the remainder of patients (37/39 [95%]). The catheter ablation system used in this study was safe, effective, and prevented coagulum formation while delivering relatively high power. In addition, shorter ablation times and radiation exposure were seen with this system. Although successful energy applications and the production of junctional rhythm were associated with higher achieved temperatures, temperature alone did not predict either endpoint. Future prospective, randomized trials are needed to confirm these findings and further evaluate the value of temperature monitoring.

The Response of the Slow Atrioventricular Nodal Pathway to Temperature

“…The mean number of applications of RF energy per patient was 5.9±3.3 (range: [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. There were no complications except for 1 patient with transient AV block.…”

“…22 Epstein et al demonstrated that the minimum temperature required for the successful ablation of the slow pathway was 48°C, and that for the appearance of junctional beats was also 48°C. 11 In terms of AV junction ablation, the mean temperature associated with the appearance of AV nodal block was 58-70°C. 22,23 The mean temperature associated with the development of accelerated junctional beats was 47-51°C.…”