Abstract 19881: Impact of Radiofrequency Application Time and Power on Lesion Volume Created by a Novel Heated Saline Enhanced Radiofrequency Needle-tip Catheter: Evidence From an MRI Lesion Validation Study

Purpose: This study was conducted to assess controllability of lesion creation in left ventricular myocardium using a novel heated saline enhanced radiofrequency (RF) needle-tip catheter. Methods: Six normal dogs underwent catheter ablation using this novel catheter (closed-end 25-gauge needle [penetration depth 6 mm], 24 radial side holes for injection of heated saline). Ablative lesions were created using different power and RF application times (21, 33, 40, 45W; application of 25, 50, 60, 75sec.; irrigation saline 60°C with 10mL/min flow). Needle penetration was assessed by intracardiac echocardiography (ICE). Hearts were explanted one week after ablation and evaluated using postmortem 3.0T-MR imaging (FSPGR sequences, 1mm slice interval). Gross pathologic and histologic characteristics of lesions were examined. Lesion volume was measured using MR images and compared to volumes obtained in gross pathology. Results: In total, 29 lesions (5 lesions with 21W/25sec, 5 with 21W/75sec, 5 with 33W/50sec, 4 with 40W/60sec, 5 with 45W/25sec and 5 with 45W/75sec) were assessed. No steam pop, perforation and lethal arrhythmia events were observed during RF application. All lesions were successfully identified on MR images. Out of the 29 lesions, 23 lesions (79.3%) were transmural. Lesion volume data are summarized in Figure. Time Δlesion volume was 50.2mm 3 /sec with 21W, 37.3mm 3 /sec with 45W and power Δlesion volume was 74.7mm 3 /W with 25sec, 47.7mm 3 /W with 75 sec. Spearman rank correlation test showed positive correlations between gross pathologic lesion volume, RF application time and MRI lesion volume (r=0.833; p Conclusions: This novel catheter created LV lesions correlates with RF application time. MR lesion size is dependent on both time and power, although, unlike other ablation tools ablation time is more important than power.