Epicardial electroanatomical mapping, radiofrequency ablation, and lesion imaging in the porcine left ventricle under real-time magnetic resonance imaging guidance—an in vivo feasibility study

Abstract

AimsMagnetic resonance imaging (MRI) is the gold standard for defining myocardial substrate in 3D and can be used to guide ventricular tachycardia ablation. We describe the feasibility of using a prototype magnetic resonance-guided electrophysiology (MR-EP) system in a pre-clinical model to perform real-time MRI-guided epicardial mapping, ablation, and lesion imaging with active catheter tracking.Methods and resultsExperiments were performed in vivo in pigs (n = 6) using an MR-EP guidance system research prototype (Siemens Healthcare) with an irrigated ablation catheter (Vision-MR, Imricor) and a dedicated electrophysiology recording system (Advantage-MR, Imricor). Following epicardial access, local activation and voltage maps were acquired, and targeted radiofrequency (RF) ablation lesions were delivered. Ablation lesions were visualized in real time during RF delivery using MR-thermometry and dosimetry. Hyper-acute and acute assessment of ablation lesions was also performed using native T1 mapping and late-gadolinium enhancement (LGE), respectively. High-quality epicardial bipolar electrograms were recorded with a signal-to-noise ratio of greater than 10:1 for a signal of 1.5 mV. During epicardial ablation, localized temperature elevation could be visualized with a maximum temperature rise of 35 °C within 2 mm of the catheter tip relative to remote myocardium. Decreased native T1 times were observed (882 ± 107 ms) in the lesion core 3–5 min after lesion delivery and relative location of lesions matched well to LGE. There was a good correlation between ablation lesion site on the iCMR platform and autopsy.ConclusionThe MR-EP system was able to successfully acquire epicardial voltage and activation maps in swine, deliver, and visualize ablation lesions, demonstrating feasibility for intraprocedural guidance and real-time assessment of ablation injury.

Evaluation of a real-time magnetic resonance imaging-guided electrophysiology system for structural and electrophysiological ventricular tachycardia substrate assessment

“…The MR-compatible catheter has two solenoid micro-coils located 2 and 11 mm proximal to the ring electrode that enabled the location and orientation of the catheter to be detected in 3D space using a dedicated MRI active tracking sequence. A custom-built MR-EP recording system (Advantage-MR, Imricor, Burnsville, MN, USA) consisting of a digital amplifier, stimulator, and host workstation was used to record, display, and analyse intra-cardiac electrograms as previously described 10 . A patient monitoring system suitable for use in the MRI environment (Invivo, Gainesville, FL, USA) was used to monitor a single lead ECG and invasive arterial blood pressure throughout the study.…”

“…In order to accurately detect the location and orientation of the mapping catheter in 3D space, a dedicated active tracking sequence was used as described previously 10 . Briefly, the X, Y, and Z co-ordinates of the catheter micro-coils were determined using the custom active tracking sequence, which was optionally interleaved with a fast balanced steady state free precession (bSSFP) imaging sequence automatically following the current catheter position.…”

Magnetic resonance imaging guidance for the optimization of ventricular tachycardia ablation

“…Current generation MR-compatible catheters cannot achieve the same resolution as multipolar mapping catheters used with high-resolution 3D EAM systems. 79 A potential workflow to performing real-time MRI-guided intervention could therefore be to perform a conventional electrophysiological assessment followed by moving the patient into the MRI scanner for intra-procedural assessment of imaging substrate, guidance with active tracking, ablation lesion delivery and lesion assessment under real-time MR guidance. Development of such a workflow will require rapid, automated segmentation and registration tools and could allow the benefits of conventional EAM assessment to be combined with real-time imaging but can realistically only be performed in hybrid X-ray and MRI catheter laboratories.…”

Advancement in cardiac imaging for treatment of ventricular arrhythmias in structural heart disease

“…163,164 Promising results from animal studies indicate that such real-time visualization of ablation lesions could be used in the future for titrating radiofrequency energy. 165 There are several other evolving technologies that might help in the future in personalized VT ablation, including body surface mapping and image-based arrhythmia modelling. A detailed description of these techniques is beyond the scope of this review, and we therefore refer to recent review articles.…”