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CA-527-02 LESION CHARACTERISTICS WITH HIGH POWER SHORT DURATION AND CONVENTIONAL RADIOFREQUENCY ABLATION WITHOUT TEMPERATURE CONTROL

      Background

      During radiofrequency (RF) ablation, resistive heating causes superficial heating and conductive heating (time dependent) extends to deeper layers. High power short duration (HPSD) ablation should result in wider but shallower lesions by reducing conductive heating. However, if HPSD is delivered with standard ablation catheters, the impact of irrigation rate is not clear.

      Objective

      Assess the effect of different irrigation rates on lesion formation, geometry and volume using HPSD ablation compared with conventional ablation.

      Methods

      This study used an ex-vivo model consisting of a circulating saline bath (37°C), an indifferent electrode, a submersible cell load, porcine heart preparations, an Ampere generator and a Flexability ablation catheter (Abbott, Minneapolis, MN, USA). For HPSD, applications were delivered at a power of 70W for 7 seconds maintaining 10-20g of force. Conventional RF was 30W for 30 seconds (10-20g). Irrigation was set at 6ml/min, 10ml/min, 15ml/min, 20ml/min and 30ml/min. Ten lesions were created at each of the five different irrigation settings using the two modalities. The tissue was stained with Triphenyl tetrazolium chloride (TTC) and a digital precision caliper was used to measure every lesion.

      Results

      Irrigation rate did not change the lesion depth using HPSD or conventional ablation (p=0.3; p=0.2 respectively). However, lesion width decreased with higher irrigation rates (p<0.001). Consequently, lesion volume was also lower (p=0.008) at higher irrigation. These findings were not seen using conventional ablation where there was no significant impact on the lesion volume (p=0.1).Lesions using HPSD were shallower (3.2±0.6mm vs 4.9±0.8mm; p<0,001) and had smaller volume (80±29mm vs 202±83mm; p<0,001) vs conventional. Lesion shape was different: conventional ablation showed maximum width in the sub-endocardium and HPSD on the endocardial surface.

      Conclusion

      Higher irrigation rate does not result in deeper lesions but has a direct impact on the lesion width and volume using HPSD. There is no benefit from using high irrigation rates in HPSD ablation performed with non-temperature-controlled catheters.