Biochemical-anatomopathological correlation of the lesions produced with standard and irrigated 4 mm radiofrequency catheters

Introduction and objectives. The influence on the size of radiofrequency le sions by cooling of the tip of the electrode remains unclear. Moreover, the possible effects of two different cooling systems, closed and open, have n ot been well differentiated. We designed this study to compare both systems of irrigated-tip catheters and the lesions produced with standard 4 mm cat heters and also to evaluate the pathological and biochemical marker release correlation (cardiac troponin I) in an experimental model. Methods. The study was performed in 20 pigs. Applying between 1-8 radiofreq uency pulses, at a power of 15, 25 or 50 watts, for 15-60 seconds to each a nimal. After 7 days, the pigs were sacrificed for anatomopathological study . Results. A total of 54 lesions were produced, 25 with standard catheters an d 29 with irrigated catheters. The mean volume of the lesions produced with standard catheters was 146 +/- 110 mul and with irrigated-tip catheters 85 6 +/- 864 mul (p < 0.001). Peak values of cardiac troponin I were also high er for irrigated catheters (18 <plus/minus> 15 ng/ml) than for standard (6. 5 +/- 3 ng/ml). The correlation between the size of the lesion and the leve ls of cardiac troponin I were 0.86 and 0.79 with the standard and irrigated -tip catheters, respectively. The incidence of cratering was higher with st andard catheters (60%) than with irrigated (27%). Conclusions. The lesions produced with an irrigated catheter are greater th an those observed with standard catheters. The mean peak value of postablat ion cardiac troponin demonstrate a good correlation with the real size of t he necrosis.