Sheath shape pattern during leadless pacemaker implantation.

Abstract

Options for shaping the delivery sheath of leadless pacemakers (LPs) based on the cardiac anatomy of patients are limited. We predicted the shape of the LP sheath during implantation using preoperative computed tomography (CT) and intraoperative fluoroscopy. Forty-eight patients with implanted LPs due to symptomatic bradyarrhythmia were divided into two groups, α-loop and non-α-loop, based on the shape of the LP delivery sheath head at implantation. Angles between the inferior vena cava (IVC) and the interventricular septum (IVST), and the IVC and right ventricular apex (RVA) were measured by CT. The relationship between the final sheath shape and position of the IVC and the right or left side of the line drawn vertically from the deflection point of the sheath in the LAO view on fluoroscopy was assessed. Angles between the IVC and IVST (44.4 ± 5.9° vs. 50.2 ± 6.8°) and IVC and RVA (52.5 ± 5.3° vs. 58.8 ± 7.8°) on CT were significantly (p < 0.01) smaller in the α-loop group. To predict the α-loop shape, a combined IVC-IVST angle < 50° and IVC-RVA angle < 55° revealed higher sensitivity (81.8%). The delivery sheath positioned right of the vertical line was more frequent in the α-loop group (90.9% vs. 23.1%, p < 0.01). When the preoperatively calculated angles of IVC to IVST and RVA on CT were narrow, the right side of the sheath in the IVC from the vertical line drawn from the deflection point in the LAO view indicated the need to shape the delivery sheath head into an α-loop during LP implantation.