Evaluation of Stereotaxis system for catheter ablation
BORDEAUX, FRANCE. The use of robotic systems for catheter ablation of atrial fibrillation (AF) and other cardiac arrhythmias has been under development for several years. There are now two main systems – the Niobe II Stereotaxis and the Hansen Sensei. The Stereotaxis system uses a soft-tipped irrigated ablation catheter that can be guided to and positioned at the desired site by varying the field direction of two permanent magnets located on either side of the patient's body. The catheter contains three magnets within the tip segment and an irrigation channel and is operated by remote control from a shielded control room.

The Hansen Sensei system uses a robotic arm (placed next to the patient at groin level) which essentially guides a flexible sheath (tube) extending from the groin to the atria through the femoral vein. The ablation catheter is threaded through the sheath with only the tip (1 cm) extending from the sheath. The movement of the sheath can be closely controlled by the electrophysiologist sitting at a remotely located console. Both systems have the great advantage of limiting radiation exposure to the operator by a factor of 10 or more.

The Bordeaux group has now completed a small-scale evaluation of the Stereotaxis system. The study included 30 consecutive paroxysmal afibbers (average age of 60 years with 77% being male) of which 90% had lone AF. The patients underwent an anatomically-guided (CARTO) pulmonary vein isolation (PVI) procedure using the Stereotaxis Niobe II ablation system accompanied by a cavotricuspid isthmus ablation when needed to eliminate right atrial flutter. NOTE: Six out of 120 veins were isolated using manual rather than robotic control. The total average procedure time was 263 minutes and average fluoroscopy time was 67 minutes. Patients were followed up at 1, 3, 6 and 12 months and in case of symptoms. After an average follow-up of 14 months, 69% of ablatees were free of atrial tachyarrhythmias (AF, atrial flutter, and atrial tachycardia). Four patients underwent a repeat ablation a year after the initial procedure. There were no major complications.

The outcome of the Stereotaxis procedure was compared with that of the standard, manually-guided procedure. This study included 44 consecutive paroxysmal afibbers (average age of 58 years with 84% being male) of which 89% had lone AF. The patients underwent a standard PVI and right atrial flutter ablation as needed. The total average procedure time was 165 minutes and total fluoroscopy time was 47 minutes. After an average follow-up of 15 months, 61.8% in the group were free of atrial tachyarrhythmias without the use of antiarrhythmics. Seven patients underwent a repeat procedure a year after the initial procedure. There was one major complication (cardiac tamponade) which was resolved satisfactorily through percutaneous drainage.

The Bordeaux evaluators conclude that, in patients with paroxysmal AF, Stereotaxis-guided PVI with an irrigated tip, magnetic catheter backed up with manual ablation whenever required, is feasible. However, it requires longer ablation, fluoroscopy and procedural times than the conventional approach – at least during the early part of the learning curve.

Miyazaki, S, et al. Remote magnetic navigation with irrigated tip catheter for ablation of paroxysmal atrial fibrillation. Circulation Arrhythmia and Electrophysiology, Vol. 3, December 2010, pp. 585-89

Editor's comment: This study and the study carried out by Dr. Karl-Heinz Kuck at the St. Georg Hospital in Hamburg conclude that medium-term results obtained using the Stereotaxis system are comparable to those obtained using conventional manual ablation. Radiation exposure to the operator is significantly less than with manual operation and this will hopefully translate into a benefit to the patient as well, as operator experience improves.