3. Discussion
Prior study has shown that catheter ablation via superior approach for AVNRT is safe and feasible. [2] Femoral approach with IVC interruption and azygos continuation may be possible but has disadvantages including (1) instability and difficulty in manipulation of catheters, (2) increased fluoroscopy time and radiation exposure, and (3) patient discomfort due to the numerous catheters.
Superior approach has been reported in catheter ablation of VT with IVC access issues including anatomical anomalies (bifurcating or tortuous veins), IVC interruption or agenesis, or IVC obstruction by prosthetic material or thrombus. [11] [12][13] [14] Using multielectrode and large curves catheters is recommended to better define the scar and border zone areas, and in accessing the RVOT. [12]
Hong Euy Lim et al. demonstrated the safety and feasibility of AF ablation via the superior approach in patients with complete interruption of the IVC. Transseptal puncture via superior approach can be challenging and requires better support with (1) Brockenbrough needle (manually bent with 150°) toward the fossa ovalis (FO), and (2) a stiffer and angulated sheath, such as the Mullins sheath, SL3 sheath, or superior transseptal access system. Additionally, a steerable sheath can make transseptal puncture and catheter manipulation in the left atrium easier. In cases of difficult transseptal puncture, utilizing transesophageal echocardiography (TEE) can provide greater certainty of safe puncture and prevent major complications. [9] [10] Integration of the 3-D mapping system with pre-acquired MR or MDCT images can improve navigation of the mapping catheter within the atria. It can also provide better accuracy of lesion placement to ensure continuity of linear ablation over the complex anatomy of the PVs and the surrounding LA antrum. [15] [16]
In our study, we present four cases who underwent catheter ablation via superior approach including AVNRT, monomorphic VT, and persistent AF with 3-D mapping system (Table 1). In these four cases, we used different vascular access including right internal jugular vein, right subclavian vein, and right femoral with azygos continuation. We chose superior approach because of (1) IVC interruption, (2) bilateral femoral venous thrombosis, (3) bilateral iliac vein total occlusion, and (4) highly tortuous vessel. Compared with conventional fluoroscopy-guided ablation, 3-D mapping system in these complex cases can provide precise cardiac anatomy and target ablation area with fewer intra-cardiac catheters. Only two catheters via two vascular access were required in our cases, with utilization of 3D mapping. In the case of VT and persistent AF, long sheaths were needed to facilitate the mapping and ablation. Complications such as puncture site hematoma, significant vessel damage, pericardial tamponade, and aortic or atrial perforation may occur in cases such as the ones presented due to the complexity of the access and ablation approach but none were recorded in our cases. All were also successfully ablated.