Comprehensive MRI-guided intracardiac electrophysiological interventions in swine using a combination of active tracking and passive real-time catheter imaging

Methods A 3D data set containing heart and thoracic vessels was acquired in 8 swine (37-42 kg) using a 1.5T MR-scanner and a breath hold 3D-whole-heart-sequence. An advanced MR-EP-platform (iSuite, Philips Research Hamburg) created auto-registered 3D-models of all cardiac chambers. Two MRI conditional steerable diagnostic and ablation catheters (Vision, Imricor Medical Systems) were inserted via femoral sheaths. Active catheter tracking was performed using the magnetic field to localize inductive coils assembled on the EPcatheter. The coils were shown as a virtual catheter icon displayed in real-time in the auto-segmented/auto-registered 3D-model, in the pre-acquired MRI planes, and during further scanning. The positions of the catheter tip were confirmed by fully balanced steady-state-freeprecession (SSFP) sequence with a frame rate of 8 per second. Initially the CS was intubated. After transseptal access the catheter was brought into all PVs. Subsequently bi-atrial SR activation map was acquired. Ablation procedures were performed alternately in the PVs, the cavotricuspidal isthmus and the posterior wall of the right atrium. For visualization of the myocardial edema and necrosis a T2-weighted turbo-spin-echo and a 2D-T1-weighted phase sensitive inversion recovery sequence was used respectively. After RVOT access the AV-node was ablated, the pig sacrificed and the explanted hearts inspected for ablation lesions.