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.