RADIOFREQUENCY CATHETER ABLATION GUIDED BY INTRACARDIAC ECHOCARDIOGRAPHY

Background Radiofrequency catheter ablation requires precise positioni ng of the ablation electrode. Fluoroscopically guided catheter manipul ation has limitations, and there are risks of radiation exposure. The purpose of this study was to examine the feasibility of guiding cathet er ablation within the right atrium with catheter-based intracardiac e chocardiography. Methods and Results A 10F, 10-MHz intracardiac imagin g catheter was used to direct an ablation electrode at four or five an atomic landmarks in the right atrium. Thirty-eight radiofrequency ener gy applications were performed in nine anesthetized dogs, and 38 lesio ns were identified on pathological examination. Lesions were created a mean of 1.9+/-2.1 mm from the ultrasound-guided site. Twenty-six of 3 8 lesions (68%) were less than 2.2 mm from the imaged site. Intracardi ac echocardiography also was used to confirm stable electrode-endocard ial contact in 37 energy applications (97%) and identified catheter mo vement in 9 energy applications (24%). Discrete lesions, microcavitati ons, and thrombi were observed in 13 (34%), 23 (61%), and 19 (50%) of 38 energy applications, respectively. Microcavitations predicted the a ppearance of thrombus. Fluoroscopy time required to create four or fiv e lesions decreased from 23 minutes in the first study to less than 2 minutes in the last five studies. Conclusions Catheter-based intracard iac echocardiography can accurately guide catheter ablation directed a t anatomic landmarks and potentially reduce ionizing radiation exposur e. Intracardiac imaging can be used to confirm endocardial contact, id entify electrode movement, and directly visualize lesions. Intracardia c echocardiography also can be used to identify microcavitations, whic h predict thrombus formation during radiofrequency energy applications .