Catheter ablation approach for DGCV-AIV VAs
Previous studies have revealed that one key point for successful ablation of DGCV-AIV VAs is the structure of DGCV-AIV being sufficiently accessed and mapped. However, the existence of anatomic obstacles in the coronary venous system limited the ablation catheter manipulation and access to the target sites in this region. In some cases, even advancing the ablation catheter to the proximal GCV is difficult. In our study, due to the obstacle of venous valves, catherter tip could not reach the proximal-middle GCV by NS approach and SS approach in 6 patients. One study reported in one patient with DGCV VAs, because of the tortuous course of GCV, catheter ablation could not access the optimal target site of VAs[8]. Contact force catheter guided deep engagement with a steerable sheath in the DGCV was then performed. The contact force catheter and steerable sheath were advanced alternately, which overcame the deflections in GCV and resulted in the deep engagement of catheter tip to DGCV and successful ablation of DGCV VAs. However, this method had its limitations. In patients with small size coronary venous system, it could be challenging to manipulate the contact force catheter and steerable sheath, as both of which were much larger than the conventional irrigated catheter and sheath in diameter. Besides, the much harder characteristics of steerable sheath may more easily cause coronary vein dissection and rupture. Another study also reported anatomic obstacles restrained successful ablation of DGCV-AIV VAs[7]. Due to the very distal portion of DGCV are usually very thin and frequently inaccessible to an ablation catheter, Kazutaka A et al. delivered a 2F microcatheter into the vein as a landmark of the ablation sites and performed ablation in the nearby endocardial structures. However, by this approach, the elimination of these VAs usually requires ablation at multiple sites at adjacent structures and because of indirect ablation, the efficacy of RFCA was usually limited. In our research, we found that an aute angle between AIV and DGCV was also another anatomic obstacle difficult to overcome when cathter ablation was performed, for which, an appropriate manipulation approach remained investigated. In addition, we found in a situation of narrow elliptical shape of CVS (Width/Height>0.69), SS approach ensured a powerful backup force for ablation catheter, which could assist catheter tip overcome a partial anatomic impediments of coronary venous system and reach the target sites in DGCV-AIV more easily, contributed to a relative higher success rate of RFCA. Thus, it was more favorable than NS approach when RFCA of DGCV-AIV VAs.
It should be noted that when catheter ablation of DGCV-AIV VAs, anatomic obstacle is not the the only factor that limits successful ablation. In clinical practice, successful ablation of DGCV-AIV VAs is associated with a network of factors, including origin sites (epicardially or intramurally), distance to adjacent coronary artery, impedance during ablation and so on.