Real-time MRI-guided placement of catheters possible in patients

Real-time MRI-guided radiofrequency (RF) ablation for atrial flutter is feasible in patients, according to a study published in the June issue of Radiology.

Radiofrequency catheter ablation is the standard therapy in atrial flutter, atrial fibrillation and other arrhythmias. Although the current modality utilized for catheter guidance is fluoroscopy, it comes with its disadvantages. Given MRI’s lack of ionizing radiation and ability to offer high-contrast images with any user-defined angulation, the modality seems to be a prospective alternative to fluoroscopy.

“Performing diagnostic and therapeutic electrophysiological (EP) interventions with MR imaging guidance requires the development of a compatible ablation system, a reliable method to visualize the catheter tip during intervention, and a workflow in patient management that accounts for the high magnetic field environment,” wrote the study’s lead author, Matthias Grothoff, MD, of the University of Leipzig Heart Center in Germany, and colleagues.

To assess if real-time MRI-guided RF ablation for atrial flutter is feasible in patients, the researchers included 10 patients with symptomatic atrial flutter who underwent isthmus ablation in their study. Two MRI conditional steerable diagnostic and ablation catheters were inserted into the coronary sinus via femoral sheaths and into the right atrium with fluoroscopic guidance in all patients. The participants then were transferred to a 1.5-T whole-body MR imager for an ablation procedure. During this procedure, the catheters were manipulated by an electrophysiologist by using a commercially available interactive real-time steady-state free precession MRI sequence.

Successful placement in standard positions occurred with all catheters. Simple programmed stimulation maneuvers were also performed. A complete conduction block was performed with MRI guidance in one of the patients. In nine of the 10 patients, creating only a small number of additional touch-up lesions was necessary to complete the isthmus block with conventional fluoroscopy.

No device or procedure-related adverse events occurred during or after MRI.

“As a next step, the handling of the catheters has to be modified to enable fully MR imaging–guided ablation procedures,” wrote Grothoff and colleagues. “However, there remain several major limitations to be overcome before this technique can be considered as an alternative to standard fluoroscopy-guided procedures.”