307 MRI-guided atrio-ventricular node ablation in swine models using MRI tracking
Journal of Cardiovascular Magnetic Resonance volume 10, Article number: A110 (2008)
MRI-guided navigation, Electro-Physiological (EP) voltage mapping of the left ventricle, as well as mapping and Radio-Frequency Ablation (RFA) at the Pulmonary Vein/Left Atrium junction, were previously demonstrated in swine models (references [1–3]). This study is an extension of the MRI-tracked technique, using simultaneous multiple-catheter tracking, to locate, perform RFA and verify ablation of the Atrio-Ventricular (AV) node, with electrical and MRI signatures. AV node ablation is a treatment component for types of arrhythmia, usually followed by pacemaker implantation.
To perform AV node ablation in an MRI scanner, utilizing clinical grade MRI-tracked catheters. To demonstrate MRI-guidance advantages in anatomic imaging and in the rapid post-delivery monitoring of the extent of ablation injury.
Intubated swines (n = 3) were used. Pre-procedural MRI included 3D ECG-gated MR Angiography and 3D wall motion Cine, which were reformatted and 3D rendered into navigational roadmaps. A 4-micro-coil MR-tracked sheath was advanced to the Right Ventricle (RV). A 5-microcoil MRI-tracked deflectable bipolar EP catheter, equipped with a 4 mm ablation tip, was passed through the sheath and used for ECG mapping and ablation. An additional tracked EP catheter was advanced into the RV and intra-cardiac ECG pacing commenced. The AV node was located by navigating on short-axis images to its assumed anatomic position, with physical contact verified electrically (Figure 1A). A slow drip of Gd-DPTA contrast was started. RFA was performed with a noise-filtered RFA generator. AV node block and ablation were confirmed on the ablation catheter's ECG signal. Following RFA, 2 mm slice contrast-enhanced 3D Myocardium Delayed Enhancement (3DMDE) was performed. Gross histology was performed following sacrifice.
Locating the AV node was a lengthy procedure (> 20 minutes). Catheter voltage (Figure 1B) and high-resolution 3D MDE (Figure 1C) demonstrated the AV node ablation rapidly (< 2 minutes). Histology verified well-positioned ablation lesions. Total node blockage was achieved in 2 pigs, partial in 1 pig.
MRI-tracked AV node ablation, simultaneously visualizing 3 catheters at 12–15 frames per second, is feasible.
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Schmidt, E.J., Thiagalingam, A., d'Avila, A. et al. 307 MRI-guided atrio-ventricular node ablation in swine models using MRI tracking. J Cardiovasc Magn Reson 10 (Suppl 1), A110 (2008). https://doi.org/10.1186/1532-429X-10-S1-A110