Conduction gap mapping of linear ablation lesions with high-density mapping

Introduction When performing linear ablation, creating contiguous and transmural lesions are technically challenging due to the difficulty in finding electrical conduction gaps. We hypothesized that high-density mapping could identify the gaps. Methods and Results This study included consecutive patients who underwent conduction gap mapping of de novo lesions (41 patients, 55 lines) and previous lesions (25 patients, 34 lines). We analyzed the utility of bipolar and unipolar conduction gap mapping and retrospectively assessed the voltage and morphology of the bipolar electrograms at the gap sites. Bipolar and unipolar propagation maps were classified into three types: the propagation wavefront traveled through the linear ablation lesions (direct leak), the wavefront jumped to an opposite site across the line and returned to the line (jump and return leak), and others (indefinite leak). In the jump and return leak maps, the site where it returned suggested a conduction gap site. Bipolar propagation maps identified 30 (54.5%) conduction gaps and unipolar maps identified 40 (72.7%) gaps at de novo linear ablation lesions (P = .01), and 32 (94.1%) gaps and 33 (97.1%) gaps, respectively, at previous lesions (P = .56). Bipolar voltage mapping did not add any further efficacy in detecting conduction gaps, and the morphology of the electrograms recorded at the gap sites was not related to the types of propagation maps. Conclusion Conduction gaps of linear ablation lesions can be visualized by high-density mapping with a high probability. Unipolar propagation, when used with bipolar mapping, may help detect conduction gap sites.