PO-05-098 CAN INTRACARDIAC ECHO HELP AVOID STEAM POPS DURING HALF NORMAL SALINE IRRIGATED VENTRICULAR ARRHYTHMIAS ABLATION?

Abstract

Irrigated radiofrequency ablation (RFA) with half-normal saline (HNS) can potentially increase lesion size, but may increase the risk of steam pops and with possible emboli or perforation. Intracardiac ultrasound (ICE) allows observation of pops, and tissue whitening and spontaneous contrast (bubbles) that may be markers of heating. We assessed the relation between audible pops and ICE observations during HNS irrigation during ventricular arrhythmia RFA in a prospective study. In 100 consecutive patients undergoing endocardial ventricular arrhythmia RFA with HNS we attempted to observe the ablation site with ICE. RFA power was titrated by the operator to a 15 - 20 Ohm impedance fall and could be adjusted for tissue whitening and increasing bubble formation on ICE. Steam pops were defined as audible or on ICE, a sudden explosion of bubbles. Of 2,210 ablation applications in 100 procedures (63.2 ± 14.5 years, 75.0% men, 82% structural heart disease, 51.0% sustained VT, LVEF 39.8 ± 15.2%), the ablation site was visualized on ICE during RFA in 1,334 (60.4%), and was not seen during 876 (39.6%) applications; 38 pops (1.7%) occurred in 21 patients; 31 were audible and 7 (18%) were visible but not audible. Fewer pops occurred when ICE visualization of the RFA site was achieved (1.0%) compared to RF applications in which the site was not visualized (2.7%, p=0.004). Of the 11 ICE-visible pops, 11 (100%) were preceded by tissue whitening and 9 (81.8%) were preceded by an increase in bubble formation. There were no embolic events or cardiac perforations. Acute success was not different for patients with vs without pops (100% vs 89.9%, p=0.140). Steam pops occurred in fewer than 2% of HNS RF applications titrated to an impedance fall but occurrence without an audible pop is common, suggesting that they are under-recognized without ICE. On ICE pops are usually preceded by tissue whitening and increased bubble formation. Pops were less frequent when the operator was able to observe the site on ICE and adjust power, but some sites are difficult to image. Use of ICE may help reduce pops which could potentially improve safety.