"The application of this promising new catheter tracking technology integrated into Artis zee offers nearly fluoroscopyfree operations even in complex ablation procedures."1
Thomas Gaspar, M.D.
Electrophysiology and Rhythmology,
Heart Center Leipzig, Leipzig, Germany
A 62-year-old female patient with lone atrial fibrillation. Treatment including a beta-blocker and specific antiarrhythmic drugs (flecainide) did fail in controlling recurrences of the arrhythmia. Stress electrocardiogram and transthoracic echocardiography has not shown relevant structural heart disease. The left ventricular ejection fraction was normal with 60 %, the left atrium was slightly enlarged (42 mm in the parasternal long axis).
Highly symptomatic, drug-refractory paroxysmal atrial fibrillation indicates catheter-interventional treatment with the aim of circumferential isolation of the pulmonary veins.
The procedure was performed under the guidance of a 3D electro-anatomic mapping system (NavX-EnSite Velocity) supplemented by a novel sensor-based electromagnetic tracking system (MediGuide; MG) installed within the fluoroscopy detector of a flat panel X-ray imaging system (Artis zee). Special sensor-equipped catheters can be localized in 3D and in real-time resulting in 4D visualization within a moving organ image, such as preacquired X-ray cine loops. Before catheter insertion two cine loops in a 20° RAO and 50° LAO were recorded for 5 sec. and a dosage of 453 μGym2, each. Based on these cine loops, the MG sensor-enabled electrophysiology catheters were advanced non-fluoroscopically and positioned in the coronary sinus and the apex of the right ventricle. Consecutively, LA angiograms were acquired for serving as dynamic cine loops during the LA procedure. For that, 50 cc of non-ionic iodinated contrast material was injected through a pigtail catheter into the common pulmonary artery trunk. The fluoroscopic acquisition started after 4 sec. of lung passage time and takes 4 sec. in a 20° RAO and 6 sec. in a 50° LAO projection, respectively. The cumulative fluoroscopy dosage after these steps was 1356 μGym2. Hereafter a single transseptal (TSP) puncture was made. For safety reasons and due to the fact that neither a TSP sheath nor a TSP needle equipped with the MG sensor is available, this was performed under fluoroscopic guidance with a steerable sheath. This resulted in a cumulative fluoroscopy time and dosage of 2.6 min. and a dosage of 1985 μGym2. Hence, no fluoroscopy was necessary up to the end of the procedure. The four PVs were reconstructed as individual NavX-EnSite anatomies with an MG sensor-equipped irrigated tip ablation catheter and subsequently served as the anchor structures to register the 3D CT image. LA mapping and ablation were performed using a specific MG sensor-equipped irrigated tip ablation catheter. That catheter could be tracked within the LA angiogram in real-time (fig. 1, 2). Circumferential ablation around both ipisilateral PVs was performed at the atrial side of the PV antrum (fig. 3). Bidirectional conduction block was the end point of the procedure, and was confirmed by the circular mapping catheter. Successful pulmonary vein isolation was performed within 159 min. with a total fluoroscopy time of 2.6 min. and a fluoroscopy dosage of 1985 μGym2.
Screen shot of the MediGuide user interface during a pulmonary vein isolation procedure in a left anterior oblique projection (LAO). Three MediGuide sensor-enabled catheters are tracked real time and non-fluoroscopically by the electromagnetic sensor field and projected as an icon on their intracardiac position within prerecorded left atrium angiographies. One catheter is placed in the coronary sinus (CS - yellow icon), one in the apex of the right ventricle (RV – blue icon) and the sensor-enabled ablation catheter is on the ostium of the right inferior pulmonary vein (Abl – red icon). During mapping of the pulmonary veins their ostia are marked by chips of different color (right superior pulmonary vein – RSPV, green chip; right inferior pulmonary vein – RIPV, red chip; left superior pulmonary vein – LSPV, blue chip; left inferior pulmonary vein – LIPV; grey chip).
Screen shot of the MediGuide user interface during a pulmonary vein isolation procedure in a right anterior oblique projection (RAO) combined with the validation of displayed catheter position on fluoroscopy (small image on left upper side). Similar to fig. 1, three MediGuide sensor-enabled catheters are tracked in real time and non-fluoroscopically by the electromagnetic sensor field and projected as an icon on their intracardiac position within prerecorded left atrium angiographies. For validation catheter positions are now visualized simultaneously on live fluoroscopy and non-fluoroscopically within the MediGuide surface. The overlay of the fluoroscopic catheter image and the non- fluoroscopic catheter icons indicates the accuracy of the system for catheter localization.
Visualization of the 3D model of the left atrium at the end of the procedure within the electroanatomic mapping system.
The statements by Siemens' customers described herein are based on results that were achieved in the customer's unique setting. Since there is no "typical" hospital and many variables exist (e.g., hospital size, case mix, level of IT adoption) there can be no guarantee that other customers will achieve the same results.
Rolf S, Sommer P, Gaspar T et al.: Ablation of Atrial Fibrillation using Novel 4D Catheter Tracking within Auto-Registered LA Angiograms. Circ Arrhythm Electrophysiol. 2012 Jul 7. [Epub ahead of print]