MRI guided electrophysiological intervention with a voltage-based electro-anatomic mapping system

Background MRI visualizes luminal & vessel-wall anatomy, and identifies edema & scar tissue, contributing to improved electrophysiological (EP) ablative procedures for treatment of Ventricular Tachycardia & Atrial Fibrillation. MRI-guided EP interventions will be performed for the foreseeable future partially in & outside MRI, due to the need for X-ray/Ultrasound-compliant devices. Electromagnetically tracked catheter procedures, today’s norm for most EP procedure phases; vascular navigation, Electro-Anatomic-Mapping (EAM, the diagnostic and therapeutic phases), can only be performed outside MRI. Separate MRI tracking is required in MRI, complicating EP procedures which require moving in & out of the bore [1,2]. Continuous catheter tracking using a single system would allow registration-free EAM in & outside MRI. The goal was developing an MR-compatible St. Jude Medical (SJM) EnSite NavX (ESN) voltage-based tracking [3]. ESN applies 5.8/8.0 kHz voltage bursts between 3 pairs of electrodes on the chest, detecting a catheter’s position [4], so a challenge for intra-MRI use is MR gradient ramps which interfere with ESN operation. Minimal MR Image Quality (IQ) reduction also needs to be insured, as well as <2oC patient-skin heating due to components in MRI.