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CA-527-03 DOES HIGH POWER - SHORT RADIOFREQUENCY ABLATION PRODUCE WIDER ATRIAL LESIONS ?

      Background

      It has been proposed that high power-short duration RF applications produce wider but shallower atrial lesions, compared to moderate power-moderate duration RF applications.

      Objective

      To compare atrial lesion size and the incidence of steam pop between RF ablation at 90Watts/4sec, 50Watts/10sec and 30Watts/30sec in the canine beating heart.

      Methods

      Six dogs were studied closed chest. 7.5 Fr ablation catheters with a 3.5 mm electrode and 66 or 56 small irrigation holes (QDOT MICRO or THERMOCOOL SMARTTOUCH SF Catheter, Biosense Webster) were positioned in the right atrium (RA). RF was delivered at 2 separate sites at 90Watts for 4sec (QDOT, 8 ml/min irrigation), 50Watts for 10 sec (SF, 15 ml/min irrigation) and 30Watts for 30sec (SF, 8 irrigation ml/min), total 12 sites in the RA in each dog with contact force 6-22 (median 11) g. After ablation, dogs were sacrificed and RF lesion size was measured by TTC staining for maximum depth, maximum diameter, endocardial diameter and epicardial diameter.

      Results

      Figure. No steam pop or thrombus occurred in any RF. 33/36 (92%) lesions were transmural in the atrial wall. There was no significant difference in maximum diameter between three groups. Endocardial diameter is smaller than epicardial diameter. Lesion depth was slightly smaller with 90W/4sec. Lung lesions were observed at 1/12 (8%) sites with 90W/4sec, 4/12 (33%) sites with 50W/10sec and 5/12 (42%) sites with 30W/30sec.