Electroanatomic mapping and radiofrequency ablation of porcine left atria and atrioventricular nodes using magnetic resonance catheter tracking.
BACKGROUND
The MRI-compatible electrophysiology system previously used for MR-guided left ventricular electroanatomic mapping was enhanced with improved MR tracking, an MR-compatible radiofrequency ablation system and higher-resolution imaging sequences to enable mapping, ablation, and ablation monitoring in smaller cardiac structures. MR-tracked navigation was performed to the left atrium (LA) and atrioventricular (AV) node, followed by LA electroanatomic mapping and radiofrequency ablation of the pulmonary veins (PVs) and AV node.


RESULTS
One ventricular ablation, 7 PV ablations, 3 LA mappings, and 3 AV node ablations were conducted. Three MRI-compatible devices (ablation/mapping catheter, torqueable sheath, stimulation/pacing catheter) were used, each with 4 to 5 tracking microcoils. Transseptal puncture was performed under x-ray, with all other procedural steps performed in the MRI. Preacquired MRI roadmaps served for real-time catheter navigation. Simultaneous tracking of 3 devices was performed at 13 frames per second. LA mapping and PV radiofrequency ablation were performed using tracked ablation catheters and sheaths. Ablation points were registered and verified after ablation using 3D myocardial delayed enhancement and postmortem gross tissue examination. Complete LA electroanatomic mapping was achieved in 3 of 3 pigs, Right inferior PV circumferential ablation was achieved in 3 of 7 pigs, with incomplete isolation caused by limited catheter deflection. During AV node ablation, ventricular pacing was performed, 3 devices were simultaneously tracked, and intracardiac ECGs were displayed. 3D myocardial delayed enhancement visualized node injury 2 minutes after ablation. AV node block succeeded in 2 of 3 pigs, with 1 temporary block.


CONCLUSIONS
LA mapping, PV radiofrequency ablation, and AV node ablation were demonstrated under MRI guidance. Intraprocedural 3D myocardial delayed enhancement assessed lesion positional accuracy and dimensions.
Department of Radiology, Brigham and Women's Hospital, Boston, MA 02115, USA. eschmidt3@partners.org
Ehud J
EJ
Schmidt
Richard P
RP
Mallozzi
Aravinda
A
Thiagalingam
Godtfred
G
Holmvang
Andre
A
d'Avila
Renee
R
Guhde
Robert
R
Darrow
Glenn S
GS
Slavin
Maggie M
MM
Fung
Jeremy
J
Dando
Lori
L
Foley
Charles L
CL
Dumoulin
Vivek Y
VY
Reddy
D000818:Animals; D001283:Atrioventricular Node / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D002304:Cardiac Pacing, Artificial; D017115:Catheter Ablation / Q000295:instrumentation; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac / Q000295:instrumentation; D004867:Equipment Design; D006325:Heart Atria / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D053783:Magnetic Resonance Imaging, Interventional / Q000295:instrumentation; D023421:Models, Animal; D011237:Predictive Value of Tests; D011667:Pulmonary Veins / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D025321:Surgery, Computer-Assisted / Q000295:instrumentation; D013552:Swine