Three-dimensional catheter positioning during radiofrequency ablation in patients: first application of a real-time position management system

Three-Dimensional Reai-Time Position Management. Introduction: Precise localization of target sites for radiofrequency catheter ablation (RFCA) of arrhythmias is hampered by the relative inaccuracy of X-ray localization procedures. This study evaluated the efficacy of a three-dimensional (3D) real-time position management system in guiding RFCA procedures in patients. Methods and Results: Patients (n = 30, age 59 ± 20 years) referred for ablation of either atrial flutter (n = 10), ventricular tachycardia (n = 15), or accessory pathways (n = 5) were studied. The real-time position management system uses ultrasound ranging techniques to track the position of an ablation catheter relative to two multitransducer reference catheters, positioned in the right atrium or coronary sinus and the right ventricle. Each catheter contains three or four ultrasound transducers. The distance between the transducer(s) is determined hy calculating the time necessary for an ultrasound pulse to reach other transducers, assuming the speed of sound in blood is 1,550 m/sec. The proximal His bundle was marked at the beginning and the end of the procedure as an electrical landmark to verify reproducibility. After identification of target sites, the position of each lesion created with the ablation catheter was marked. Successful ahlation was achieved in 94% of the patients. The distance between the location of the proximal His hundle as marked at the beginning and at the end of the procedure was 2.0 ± 1.2 mm (range 1.5 to 3.5). Conclusion: The new 3D real-time position management system facilitated RFCA procedures as it allowed accurate and reproducible 3D tracking of the mapping and ablation catheter.