Cardioscopic guidance of linear lesion creation for radiofrequency ablation

Background. The broad use of catheter ablation of atrial fibrillation is limited by the difficulty inherent in creating transmural linear lesions under fluoroscopy. Therefore, we evaluated cardioscopy as a more accurate method of guiding the catheter for the placement of linear lesions. Methods. Nineteen swine underwent endocardial ablation to create linear conduction block lesions in the right atrium under cardioscopy (group I, n = 13) or fluoroscopy (group II, n = 6). In both groups, the linear lesion was created between the superior and inferior vena cava, perpendicular to hexapolar electrodes placed on the epicardial surface. Each swine received two pairs of epicardial hexapolar electrodes: one pair to measure the conduction delay time across the ablated line and another pair for pacing. The time spent to complete the ablation, number of trials and effective ablations, ratio of effective ablations to trials, length of the lesion, conduction delay under pacing, and postmortem pathology were compared between the two groups. Results. Statistically significant differences were found for the time required for ablation, ratio of effective ablation to total number of trials, and conduction delay. Histologic analysis revealed more homogenous, continuous lesions in group I. Conclusions. Cardioscopy facilitated the placement of a conduction block line more efficiently than ablation performed under fluoroscopy. Landmarks of tissue relevant to ablation are readily visualized by cardioscopy. Moreover, cardioscopy can be useful for the development of a guiding catheter for the ablation of atrial fibrillation.