Purpose: Generator impedance (Im) mapping with constant contact force (CF) by tip catheter at PV isolation (PVI) was assessed for a proposal of tissue characterization at PV-LA junction (PV-LAJ).
Methods: In this observational, prospective, single-center study, Im mapping at constant CF = 10 g (± 2 g) was performed before PVI at PV-LAJ. PV in-vein, PV ostium (PVos), and antrum (PVan) contours were manually traced based on the 3D electroanatomic map (3DEAM) integrating intracardiac echocardiography and computerized tomography. PVan contour-methods based on Im mapping was defined on 3DEAM as the atrial-like Im contour closest to PVos, and its distance from anatomical PVan contour > 5 mm was assumed as the non-concordance marker between contour and methods.
Results: Sixty-two patients (62 ± 9 years; 43 males) were enrolled, and 244 PV-LAJ were assessed. From in-vein PV to LA and, less prominently, from PVos to PVan and LA, Im showed a unidirectional decrease with highly variable individual-specific distribution and values. PVan non-concordance was found in 59/665 segments (8.8%), 18% of PV-LAJs, and 53% of pts; it prevailed in superior PV-LAJ and measured on average 7.2 ± 1.1 mm. Im decrease patterns and non-concordance were not associated with any clinical or anatomical feature, including PV dimensions and shape.
Conclusions: Im mapping of LA-PVJ at constant CF added to 3DEAM may consistently track the tissue transition from PV to LA. PVan identified by Im was often located more toward LA than the 3D anatomical PVan, particularly in LSPV, suggesting the potential advantage of avoiding ablation of venous-like tissue. Im mapping can deserve further investigation for target characterization at LA-PVJ.
Keywords: Atrial fibrillation; Pulmonary vein imaging; Pulmonary vein isolation; Pulmonary vein mapping.
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