Abstract 2742: Characteristics of Epicardial Lesions Delivered With an Externally-Irrigated Catheter Using Multiple Irrigation Rates
Background: Saline irrigation during radiofrequency ablation has been shown to improve lesion size during epicardial ablation. However, when using externally-irrigated catheters, the optimum rate of saline irrigation is unknown. To this end, we performed an in vivo evaluation of the effects of multiple irrigation rates on lesion size during epicardial ablation with an externally-irrigated catheter.
Methods: In 9 normal sheep, epicardial access was obtained using a percutaneous subxyphoid approach. Following placement of a sheath in the epicardial space, a 3.5mm externally-irrigated catheter (Biosense Inc) was used to deliver lesions to the epicardial surfaces of the right and left ventricles at 30 W and either 5 cc/min (4 sheep) or 30 cc/min (5 sheep) irrigation rates. During ablation, the impedance, temperature, and power were continually recorded. After ablation, the animals were sacrificed and the heart explanted for gross examination of lesion dimensions.
Results: A total of 66 lesions were delivered: 25 at 5 cc/min, 41 at 30 cc/min. Of these, only 17/25 (68.0%) at 5 cc/min and 17/41 (41.5%) at 30 cc/min were identified on gross examination (p = 0.044). The ablation and lesion characteristics of the visible lesions are shown in the Table⇓. The maximum temperature and impedance change were greater at the 5 cc/min irrigation rate. Additionally, with the lower irrigation rate, the larger surface dimensions of the lesions translated to a larger lesion volume. However, there was no difference noted in maximum lesion depth between the two rates.
Conclusions: The use of lower irrigation rates during epicardial ablation with an externally-irrigated catheter translates to larger lesions; however, the lesion depth is unchanged.