Abstract 13166: Externally Irrigated Radiofrequency Ablation With Low Osmolarity Irrigant for the Treatment of Cardiac Arrhythmias

Introduction: Certain cardiac arrhythmias arise from deep or thick myocardium and may be refractory to standard external irrigated ablation. Externally irrigated ablation (EIA) is generally performed with normal saline (NS) as the infusing irrigant. Recent data suggest that larger ablation lesions can be created by decreasing the irrigant osmolarity. Hypothesis: We sought to evaluate the use of half normal saline (HNS) as the irrigant in externally irrigated ablation under ex vivo and in vivo conditions. Methods: Bovine myocardium was placed in a circulating saline bath in an ex vivo model. Two externally irrigated ablation catheters were oriented across from each other, with myocardium in between. Sequential unipolar ablations with HNS were performed at 50 Watts for 60 seconds, and ablation lesions were compared to using NS or HNS irrigation. In addition, a retrospective analysis was performed of all ablations using HNS completed at the University of Colorado from 2015-2016. Results: In vivo porcine ablations with HNS irrigation generated larger lesions, compared to control ablations using standard NS irrigation, and there was no increased incidence of steam pops (Figure 1). Clinically, 7 cases were identified that utilized HNS as the irrigant in EIA for refractory arrhythmias (1 atrial tachycardia, 6 VT/PVC cases). Acute success was achieved in 7/7 of procedures, with no recurrences at a mean follow up of 109 days. There were no complications (Figure 2). Conclusions: By decreasing irrigant osmolarity and charge density in EIA through the use of HNS, larger ablation lesions can be created to target deep arrhythmia circuits refractory to standard ablation.