Cryothermal cooled radiofrequency ablation increases lesion size without risk of thrombus formation

Abstract

Saline irrigation cooling creates larger and deeper radiofrequency (RF) ablation lesions, but is limited by the requirement for an above-freezing temperature of irrigated saline. A cryothermal cooling source may overcome this limitation to increase the lesion dimension and reduce the risk of thrombus formation. METHODS: We compared the lesion dimensions created by 1) RF and 2) salineirrigated RF (SI RF) using a 7 F, 4mm tip electrode catheter, 3) cryoablation (Cryo) and 4) cryothermal cooled RF (Cryo+RF) using a 10 F, 6.5 mm tip electrode catheter and Cryo system (CryoCor, CA) in vertical (V) or horizontal (H) orientiation to a thigh muscle preparation. All 3 modes of RF were delivered for 1 minute at 50W & 60°C, and Cryo was delivered with double-5 minutes freeze-thaw cycles. RESULTS: Of 211 (V=106, H=105) created, SI RF and Cryo+RF created deeper lesion than RF or Cryo application alone (Fig, p< 0.05). In all 4 modes of application, lesions diameter were greater with V than H orientation (Fig, p<0.05). Cryo and Cryo+RF were associated with a significant lower incidence of thrombus formation on the lesions compared with RF and SI RF (0/87vs.26/124, p<0.01). CONCLUSIONS: Cryothermal cooling during RF application resulted in a similar lesion dimension as SI RF. Both Cryo+RF and SI RF created significantly deeper lesions than Cryo, and significantly deeper and larger lesions than RF. The use of Cryo and Cryo+RF were associated with a lower risk of thrombus formation than RF and SI.