The Technology of Homogeneous Scar Tissue Creating as a Result of Ablation of the Atrial Wall with a Radiofrequency Bipolar Clamp: an Experimental and Clinical Study.

Abstract

The objective of this study was to develop a radiofrequency ablation technique to create a homogeneous scar tissue in the atrial myocardium. In the double-blinded morphological stage of the study, the left atrial appendage was used as an anatomical model to investigate the efficacy of one experimental and two conventional techniques to create ablation lines. Then, these lines were studied by morphologists. The clinical stage involved investigation of the outcomes of the developed technique for creation of ablation lines. During thoracoscopic radiofrequency fragmentation of the left atrium, all ablation lines were created using the experimental radiofrequency technique. In all histological sections of ablation lines created using the criterion of "steady decrease in the time to transmurality", there were no intact (viable) cells, in contrast to the other two conventional methods, i.e., a homogeneous scar of the atrial wall. Investigation of clinical efficacy of this developed technique revealed recurrent atrial fibrillation only in six of 137 patients (4.4%) at median follow-up time of 36 (10; 58) months. None of the patients developed specific complications (wall perforation or bleeding). According to intracardiac mapping performed after the end of the blind period, the sources of atrial fibrillation in these six patients were outside the radiofrequency ablation zone (perimitral or in the right atrium). A steady decrease in the time to transmurality should be considered as the priority intraoperative criterion for the formation of a homogeneous scar during radiofrequency ablation of the left atrium wall using a bipolar ablation clamp.