Search

Objectives: To evaluate the feasibility of performing comprehensive Cardiac Magnetic resonance (CMR) guided electrophysiological (EP) interventions in a porcine model encompassing left atrial access., Methods: After introduction of two femoral sheaths 14 swine (41 ± 3.6 kg) were transferred to a 1.5 T MR scanner. A three-dimensional whole-heart sequence was acquired followed by segmentation and the visualization of all heart chambers using an image-guidance platform. Two MR conditional catheters were inserted. The interventional protocol consisted of intubation of the coronary sinus, activation mapping, transseptal left atrial access (n = 4), generation of ablation lesions and eventually ablation of the atrioventricular (AV) node. For visualization of the catheter tip active tracking was used. Catheter positions were confirmed by passive real-time imaging., Results: Total procedure time was 169 ± 51 minutes. The protocol could be completed in 12 swine. Two swine died from AV-ablation induced ventricular fibrillation. Catheters could be visualized and navigated under active tracking almost exclusively. The position of the catheter tips as visualized by active tracking could reliably be confirmed with passive catheter imaging., Conclusions: Comprehensive CMR-guided EP interventions including left atrial access are feasible in swine using active catheter tracking., Key Points: • Comprehensive CMR-guided electrophysiological interventions including LA access were conducted in swine. • Active catheter-tracking allows efficient catheter navigation also in a transseptal approach. • More MR-conditional tools are needed to facilitate left atrial interventions in humans.

Aims: Recently cardiac magnetic resonance (CMR) imaging has been found feasible for the visualization of the underlying substrate for cardiac arrhythmias as well as for the visualization of cardiac catheters for diagnostic and ablation procedures. Real-time CMR-guided cavotricuspid isthmus ablation was performed in a series of six patients using a combination of active catheter tracking and catheter visualization using real-time MR imaging., Methods and Results: Cardiac magnetic resonance utilizing a 1.5 T system was performed in patients under deep propofol sedation. A three-dimensional-whole-heart sequence with navigator technique and a fast automated segmentation algorithm was used for online segmentation of all cardiac chambers, which were thereafter displayed on a dedicated image guidance platform. In three out of six patients complete isthmus block could be achieved in the MR scanner, two of these patients did not need any additional fluoroscopy. In the first patient technical issues called for a completion of the procedure in a conventional laboratory, in another two patients the isthmus was partially blocked by magnetic resonance imaging (MRI)-guided ablation. The mean procedural time for the MR procedure was 109 ± 58 min. The intubation of the CS was performed within a mean time of 2.75 ± 2.21 min. Total fluoroscopy time for completion of the isthmus block ranged from 0 to 7.5 min., Conclusion: The combination of active catheter tracking and passive real-time visualization in CMR-guided electrophysiologic (EP) studies using advanced interventional hardware and software was safe and enabled efficient navigation, mapping, and ablation. These cases demonstrate significant progress in the development of MR-guided EP procedures., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.)

Real-time magnetic resonance imaging (MRI) combines the advantages of excellent soft-tissue characterization in a true 3D anatomical and functional model with the possibility of lesion and gap visualization without the need of any radiation. Therefore, real-time MRI presents a particularly attractive imaging technology to guide electrophysiology studies and catheter ablation procedures. This article aims to provide an overview on current routine clinical application of MRI in the setting of interventional electrophysiology. Furthermore, development of real-time MRI guided electrophysiology studies and first experiences with MRI guided catheter ablation procedures are depicted. In this context advantages, challenges and limitations of real-time MRI guided catheter ablation as well as future perspectives are discussed.

Purpose: To assess if real-time magnetic resonance (MR) imaging-guided radiofrequency (RF) ablation for atrial flutter is feasible in patients., Materials and Methods: The study complied with the Declaration of Helsinki and was approved by the local ethics committee. All patients were informed about the investigational nature of the procedures and provided written informed consent. Ten patients (six men; mean age ± standard deviation, 68 years ± 10) with symptomatic atrial flutter underwent isthmus ablation. In all patients, two MR imaging conditional steerable diagnostic and ablation catheters were inserted into the coronary sinus via femoral sheaths and into the right atrium with fluoroscopic guidance. The patients were then transferred to a 1.5-T whole-body MR imager for an ablation procedure, in which the catheters were manipulated by an electrophysiologist by using a commercially available interactive real-time steady-state free precession MR imaging sequence., Results: All catheters were placed in standard positions successfully. Furthermore, simple programmed stimulation maneuvers were performed. In one of 10 patients, a complete conduction block was performed with MR imaging guidance. In nine of 10 patients, creating only a small number of additional touch-up lesions was necessary to complete the isthmus block with conventional fluoroscopy (median, three lesions; interquartile range, two to four lesions)., Conclusion: Real-time MR imaging-guided placement of multiple catheters is feasible in patients, with subsequent performance of stimulation maneuvers and occasional complete isthmus ablation.

Aims: Magnetic resonance imaging (MRI) in the context of electrophysiology (EP) studies facilitates visualization of complex three-dimensional anatomy and the underlying arrhythmogenic substrate, real-time passive visualization of catheters, atrial and ventricular function and complications, as well as lesion visualization during the ablation without radiation. In the following we report on our first experience of a real-time MRI-guided EP study demonstrating current possibilities and drawbacks., Methods and Results: Five consecutive patients (one male, four female; mean age 66 ± 11 years) with symptomatic arrhythmias, three patients with highly symptomatic typical atrial flutter, presented to our hospital for isthmus ablation, one patient for an EP study and one for slow pathway ablation in atrioventricular node re-entry tachychardia. The four ablations were performed successfully in a conventional EP laboratory and complete bidirectional isthmus block was confirmed in three patients with atrial flutter. After the procedure in the EP laboratory all five patients were transferred to a 1.5 T whole-body MRI scanner (Intera) for a diagnostic EP procedure. Two MRI compatible steerable diagnostic/ablation catheters (Vision) were inserted via the femoral sheaths and manipulated by an experienced electrophysiologist using a commercially available interactive real-time steady-state free precession sequence (repetition time = 3 ms, echo time = 1 ms, flip angle = 35°, slice thickness = 10 mm, frame rate = 8/s). All catheters could be placed successfully in the right atrium and ventricle, confirmed by intracardiac electrograms, using passive catheter tracking. Furthermore, simple programmed stimulation maneuvers were performed. During and after the procedure, no adverse effects were observed in any patients., Conclusion: To our knowledge, this is the first series of patients with real-time MRI-guided placement of multiple catheters with subsequent performance of stimulation maneuvers. Besides the mentioned benefits, this technology still encounters several limitations, which have to be solved before application in a routine clinical setting. Challenges arise from delineation of precise surface electrocardiogram recordings in the MRI setting along with intracardiac electrograms, easier handling and visualization of catheters, facilitation of immediate defibrillation in the MRI setting and implementation of an active catheter tracking system.