Counter intuitive relations between in vivo RF lesion size, power, and tip temperature

Radiofrequency (RF) lesion size in vitro is positively correlated with applied power and catheter tip temperature. However, the relation between RF lesion size, power, and tip temperature in vivo remains unclear. We hypothesized that due to flow, anatomy and tip contact effects in vivo, increased ti...

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Bibliographic Details
Published in:Journal of interventional cardiac electrophysiology 2003-12, Vol.9 (3), p.309-315
Main Authors: MUKHERJEE, Rupak, LAOHAKUNAKORN, Preecha, WELZIG, M. Charles, COWART, Kathryn S, SAUL, J. Philip
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Cardiology. Vascular system
Catheter Ablation
Endocardium - surgery
Medical sciences
Swine
Temperature
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Summary:Radiofrequency (RF) lesion size in vitro is positively correlated with applied power and catheter tip temperature. However, the relation between RF lesion size, power, and tip temperature in vivo remains unclear. We hypothesized that due to flow, anatomy and tip contact effects in vivo, increased tip temperature would be inversely related to applied power and RF lesion size. RF lesions were created on the endocardium of 16 pigs using 5, 6, and 7 Fr catheters. The ablation generator was set to achieve a temperature of 70 degrees C. RF lesions were created in different regions of the heart so as to encompass a wide range of blood flow and catheter movement conditions. RF lesions were measured acutely (DIMEN, mm) and correlated with average power applied (POWER, W), and average tip temperature (TEMP, degrees C). The POWER and TEMP relation was also examined. For TEMPs below 55 degrees C, the power output from the generator was typically maximized at 50 W. At TEMPs above 55 degrees C, POWER decreased exponentially with increasing TEMP (POWER = 50 - exp(-((41-TEMP)/7)), r = 0.98, p < 0.05). Further, DIMEN tended to be inversely related to TEMP (Slope: -0.07 +/- 0.04, r = -0.15, p = 0.07); but, was positively related to POWER (Slope: 0.04 +/- 0.02, r = 0.23, p < 0.05). These relations varied by tip size and estimated local blood flow characteristics. In vivo, variable tissue contact and flow yield DIMEN-POWER-TEMP relations opposite to those found in vitro. These counterintuitive results suggest that maximum in vivo RF lesion size is achieved when power is maximized at tip temperatures between 50 and 60 degrees C.
ISSN:1383-875X
1572-8595
DOI:10.1023/A:1027426907668