PO-04-062 CRYOABLATION OF INTRAMURAL SUBSTRATE IN AN IDIOPATHIC CRUX VT MAPPED BY NAVIGATING OTHERWISE INACCESSIBLE CS ANATOMY USING 2FR MAPPING CATHETER

Abstract

Idiopathic cardiac crux VTs are are difficult to map and ablate due to their inaccessible location often requiring epicardial ablation. We report a unique case of a recurrent idiopathic crux VT originating near a trifurcated confluence of CS branches that required extensive mapping only accessible with the 2Fr EP catheter that was successfully ablated with cryoablation (due to proximity to coronary artery) from within the CS and the site-opposite (epicardially). Case Report A 40 year old man with idiopathic VT (normal Echo and cardiac MRI without LGE), prior endocardial VT ablation (RV septum and mid MCV), asthma, OSA, and the Arnold-Chiari malformation, was noted to have continued symptomatic PVCs and monomorphic wide-complex tachycardia at 164 bpm. A monomorphic VT (Figure) with CL 320-380 ms was only inducible with isoproterenol infusion at 20mcg/kg/min. We attempted to better define the CS anatomy and assess if there is a route via the CS to reach the Crux. The main body CS was noted to have a trifurcation into the MCV, a posterolateral branch and an anterior branch (extension of the CS main body) all meeting at an area of confluence (Figure 1). Detailed mapping was made possible using the CS-L telescoping catheter to carry the smaller 2French EP Star catheter deep into the multiple CS branches. We noted that the proximal MCV was 28ms early in VT (but not the best pace match) and the proximal lateral CS branch across from the MCV early site within the confluence had the best pace match. This suggests the origin was likely deep in between the two sites with the exit closer to the lateral branch site. Given that we noted that the PDA is in borderline proximity (5-6mm) to the site of ablation on coronary angiography, we chose to use to cryoablation (8 minute lesions) at the confluence of these branches at the marked sites to mitigate coronary injury. VT terminated with ablations at this site. Epicardial mapping was performed and no scar was noted. An additional single lesion was performed at the site opposite from the confluence with the best pace-map and VT was no longer inducible on repeat testing with isoproterenol. CSL telescoping catheter harboring the EP star catheter can be used to overcome challenging CS anatomy to bracket the Crux VT origin. Cryoablation (not without risk completely) can be potentially effective for Crux VTs approached from CS, especially if within borderline proximity to a coronary artery.