Atrial Fibrillation Ablation

Combined with the magnetically enabled radiofrequency (RF) ablation catheters (NaviStar® RMT ThermoCool® and NaviStar® RMT, Biosense Webster, Inc., Diamond Bar, CA) and an advanced electroanatomic mapping system (CARTO RMT, Biosense Webster, Inc.), Stereotaxis provides a fully integrated solution for the ablation of AF. The pliable nature of the magnetic catheter combined with the precision of computer-assisted navigation allows the physician to reach all structures in the left atrium and to confidently address the thin tissue of the posterior wall. Automated features of the Navigant software can facilitate mapping and improve the efficiency of linear lesion delivery.

The hallmark of magnetically-navigated catheters is their flexible properties that allow them to traverse along the cardiac wall without delivering excessive force to the tissue. Higher forces are associated with increased incidence of steam pop, which may be associated with increased risk for perforation. Magnetic catheters, however, follow a different paradigm for lesion delivery by providing superior stability and consistent contact with the cardiac wall at lower contact forces. This constant contact leads to effective lesion formation and magnetic precision and may facilitate the contiguousness needed for effective vein isolation in AF ablation cases.

Porcine 1eft atrial lesions showing a continuous line of transmural lesions (LA roof lesion) and the lesion line connecting the right superior pulmonary vein to the left inferior pulmonary vein (LA posterior lesion) -- a) Necropsy image, b) CARTO map with red ablation points. (Stereotaxis, Inc., Data on File)

Clinical data from centers around the world reinforce the value of Stereotaxis in the ablation of complex left-sided arrhythmias such as AF. For example, data from Dr. Xu Chen at the Rigshospitalet in Copenhagen, Denmark showed 95% acute success in a series of 81 patients treated with Stereotaxis' magnetic irrigated catheter (Chen, HRS 2009). Performing standard ablation techniques, the total case time averaged 140 minutes and fluoroscopy time was a remarkable 7 minutes on average. Eighty-nine percent of these patients remained symptom free at one year, and 65% of the patients in this group who underwent instrumented two week monitoring were completely free from arrhythmia.

Caption: Generator settings included temperature limit of 48 °C, power limit of 30-40 W, RF time of 60 seconds, and irrigation flow rate of 10-20ml/min. During RF ablation careful monitoring of impedance, tip temperature, and RF power curves are performed (Chen, HRS 2009).

Additional published data from Prof. Carlo Pappone in Italy demonstrated 100% acute success in a similar patient group (Pappone, Heart Rhythm 2010). After 12 months of follow up, 90% of the paroxysmal patients and 80% of the long-term persistent patients in this study were in normal sinus rhythm and were not taking anti-arrhythmic medications. Most importantly, there were no complications noted in either of these patient series.

Though catheter ablation of AF is a reasonably safe procedure, there is still a risk of significant adverse events. These major complications can include perforation and tamponade and, in some cases, can lead to perioperative mortality. Stereotaxis ablation has been shown to reduce the risks associated with complex ablation procedures by up to 28 times, as is demonstrated by the graph.

Use of Stereotaxis can significantly reduce the amount of radiation exposure to both patients and physicians during AF ablation. A study by Arya and colleagues from Leipzig, Germany showed that fluoroscopy can be reduced by more than 50% when magnetic navigation is employed for AF ablation (Arya, Cardiostim 2010).