Evaluation of Radiofrequency AblationIrrigation Type: InVivo Comparison of Normal Versus Half-Normal SalineLesionCharacteristics.

Abstract

This study investigated the impact of the type of catheter irrigant used during delivery of radiofrequency ablation. The use of half-normal saline (HNS) as an irrigant has been suggested as a method for increasing ablation lesion size but has not been rigorously studied in the beating heart or the use of a low-flow irrigation catheter. Sixteen swine underwent left ventricular mapping and ablation using either normal saline (NS) (group 1: n=9) or half-normal saline (HNS) (group 2: n=7). All lesions were delivered using identical parameters (40W with 10-second ramp, 30-second duration, 15ml/min flow, and 8- to14-g target contact force). An occurrence of steam pop, catheter char, or thrombus was assessed using intracardiac echocardiography and catheter inspection following each application. Lesion depth, width, and area were measured using electronic calibers. A total of 109 lesions were delivered in group 1 and 77 in group 2. There were significantly more steam pops in group 2 (32 of 77 [42%] vs. 24 of 109 [22%], respectively). The frequencies of catheter tip char were similar (group 1: 9 of 109 [8%] vs. group 2: 10 of 77 [13%]; p=0.29). Lesion depths, widths, and areas also were similar in both groups. The use of an HNS irrigant using a low-flow open irrigated ablation catheter platform results in more tissue heating due to higher radiofrequency current delivery directed to tissue, but this can lead to higher rate of steam pops. In this invivo porcine beating-heart model, the use of HNS does not appear to significantly increase lesion size innormal myocardium despite evidence of increased radiofrequency heating.