Interactive real-time mapping and ablation of the pulmonary veins and cavotricuspid isthmus in an ovine model with an externally-irrigated MRI-compatible ablation catheter

Abstract

Summary In recent years MRI-guided interventional electrophysiology (EP) has rapidly emerged as a promising alternative to conventional X-ray guided ablation. We present a novel MRI-compatible electrophysiologic ablation and recording system, performing realistic biatrial simulated procedures. Background To date, preclinical studies evaluating MRI-guided ablation have used non-irrigated catheters limited to test lesions in the right heart. Modern complex EP procedures require externally irrigated catheters to produce adequate lesion depth. We present the first feasibility study of an externally-irrigated MRI-compatible ablation catheter, and integrated EP pacing and recording system. We demonstrate the feasibility of pulmonary vein (PV) and cavotricuspid isthmus (CTI) ablation, the targets of ablation in atrial fibrillation and typical atrial flutter respectively. Methods An externally irrigated MRI-compatible ablation and diagnostic electrophysiology catheters and integrated EP recording system (Imricor Medical Systems, Burnsville, MN) were tested in n=11 sheep, in a 1.5T MRI scanner. The diagnostic catheters were placed in the coronary sinus, and right ventricula ra pex. Power controlled (40W, 120 second duration) lesions were formed at the pulmonary veins and cavotricuspid isthmus with the ablation catheter. Real-time intracardiac electrograms were recorded during MR imaging. Steady state free precession (SSFP) non-breath-hold images were repeatedly acquired to guide the catheter to the target region using passive catheter tracking. Markers in the catheter were used to ensure adequate visualization of the catheter. Lesion visualization was performed using both noncontrast (T2-weighted turbo spin echo pulse sequence) and gadolinium-DTPA enhanced T1-weighted imaging (inversion-recovery gradient echo pulse sequence).