Analysis of Ablation Curves to Predict Transmural Lesions Using an Epicardial Bipolar Irrigated Radiofrequency Clamp in Pigs and Humans

OBJECTIVE: It is currently not known at what time point a lesion made with the bipolar irrigated radiofrequency clamp (Cardioblate™ Gemini-S, Medtronic, Galway, Ireland) is transmural. This study aimed to explore typical patterns of ablation curves to potentially predict the transmurality of ablation lesions created with the Gemini-S clamp during atrial fibrillation (AF) ablation. METHODS: Ablations were performed on the atria and ventricles of 4 pigs. After ablation, the animals were sacrificed, and macroscopic evaluation was performed to identify the transmurality of the lesions. Typical patterns of ablation curves predicting transmurality were retrospectively identified. Second, a retrospective analysis of typical patterns in human ablation curves was performed to identify potential additional parameters associated with transmurality. Furthermore, the typical patterns identified in the pig experiments were retrospectively analyzed in human ablation curves. RESULTS: Three typical patterns of transmurality were identified in the ablation curves in pigs. Type I was a sharp impedance rise, type II was 3 power drops of at least a 2-energy-level decline in 1 ablation cycle, and type III was a power drop (<11 s) with subsequent hovering of power levels between 15 and 25 W. In 11 hybrid AF ablation patients, 272 applications were performed via the left (41.9%) and right (58.1%) side. Of these ablations, 46.3% were classified as transmural based on the 3 typical patterns of transmurality identified in the pig experiments. CONCLUSIONS: Three typical patterns associated with transmurality have been identified using the Gemini-S clamp. These preliminary types need to be tested and validated in the clinical setting during hybrid AF ablation.