Application Of Unipolar Electrogram Mapping In Catheter Radiofrequency Ablation For Paroxysmal Atrial Fibrillation

OBJECTIVE:Pulmonary vein isolation(PVI)plays a corner stone role in catheter ablation for atrial fibrillation.Transmural lesions are the key for PVI.How to judge achievement of transmural lesions and distinguish the conduction gaps still remain difficulty.Previous studies have demonstrated that changes of unipolar electrogram is associated with transmural lesions.However,little was known about how to changes of unipolar electrogram patterns around the pulmonary vein ostia after ablation.This study aimed to analyze the different patterns of unipolar electrogram in different continuous circular lesions regions after ablation and verify the effectiveness of unipolar electrogram guided PVI.Methods: Patients diagnosed with paroxysmal atrial fibrillation who received radiofrequency catheter ablation were admitted to the Heart Center of Zhongshan Hospital affiliated to Dalian University from January 2018 to December 2019.PVI was achieved by contiguous point-by-point radiofrequency catheter ablation.Unipolar electrogram was recorded by the ablation catheter.Both continuous circular lesions were divided into six regions.Two points were randomly chosen from each region to analyze unipolar electrogram type after ablation.After the PVI is completed,the unipolar electrogram is used to identify potential changes looking for gaps for analysis.All the patients were followed for atrial arrhythmias recurrence.RESULTS: A total of 61 patients were enrolled into the study.All patients completed pulmonary vein isolation during the procedure.A total of 1489 radiofrequency ablation points are collected for unipolar electrogram after ablation.All the recorded unipolar electrogram turned to complete positive.Most unipolar electrogram in the same region were similar after ablation.The unipolar electrogram morphology after ablation was divided into three different types defined as R patterns,RR’ patterns and M patterns.M patterns mostly appeared in anterosuperior(52%),roof(48%)regions of left continuous circular lesions and posteroinferior(51%)regions of inferior right continuous circular lesions.The non-M patterns(R and RR’)mostly appeared in(94%)regions of left continuous circular lesions,roof(84%)and anteroinferior(83%)regions of inferior right continuous circular lesions.After a mean follow-up time of 12 ± 7 months,48(79%)patients remained in sinus rhythm.CONCLUSIONS: The changes of unipolar electrogram at the ablation site before and after ablation is an important method to evaluate the transmural lesions.It indicates that unipolar mapping could useful to guide the catheter ablation for atrial fibrillation.