Temperature response following nontraumatic low power radiofrequency application

A marker for the efficiency of heating would be helpful in radiofrequency a blation of tachyarrhythmias. We hypothesized that changes of the catheter t ip temperature during nontraumatic, very low power radiofrequency exposure would correlate with the temperature achieved during radiofrequency ablatio n, and therefore, could be used as a marker for heating efficiency. In 71 a blation attempts for drug refractory supraventricular tachycardias, the cat heter tip temperature response to a 1-W-5-second test pulse was measured. S ubsequently at the same site, radiofrequency current was delivered with a t arget temperature of 70 degrees C and a power limit of 50 W. The test pulse , with a measured power level of 1.62 +/- 0.28 Mi resulted in a heating eff iciency of 0.78 +/- 0.60 degrees C/W. During ablation, the achieved tip tem perature was 52.9 +/- 7.5 degrees C, requiring a power output of 40.7 +/- 1 0.9 W. The heating efficiency was 0.57 +/- 0.74 degrees C/W. The correlatio n between heating efficiency at low power and during radiofrequency ablatio n was linear with a correlation coefficient of 0.88. Regression analysis de monstrated that a heating efficiency above 1 degrees C/W predicts a mean ab lation temperature above 50 degrees C with more than 95% confidence interva l. The temperature response to a very low power radiofrequency application correlates with the temperature rise achieved during radiofrequency ablatio n. It is suggested that delivery of low power radiofrequency current could be used to determine and monitor efficiency of heating during catheter mapp ing and ablation procedures.