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

Introduction: Precise localization of target sites for radiofrequency cathe ter ablation (RFCA) of arrhythmias is hampered by the relative inaccuracy o f X-ray localization procedures. This study evaluated the efficacy of a thr ee-dimensional (3D) real-time position management system in guiding RFCA pr ocedures in patients. Methods and Results: Patients (n = 30, age 59 +/- 20 years) referred for ab lation of either atrial flutter (n = 10), ventricular tachycardia (n = 15), or accessory pathways (n = 5) were studied. The real-time position managem ent system uses ultrasound ranging techniques to track the position of an a blation catheter relative to two multitransducer reference catheters, posit ioned in the right atrium or coronary sinus and the right ventricle. Each c atheter contains three or four ultrasound transducers, The distance between the transducer(s) is determined by calculating the time necessary for an u ltrasound 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 a nd the end of the procedure as an electrical landmark to verify reproducibi lity, After identification of target sites, the position of each lesion cre ated with the ablation catheter was marked. Successful ablation was achieve d in 94% of the patients, The distance between the location of the proximal His bundle 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 RFC A procedures as it allowed accurate and reproducible 3D tracking of the map ping and ablation catheter.