Surface steel ball calibration - A novel method for facilitating fluoroscopic measurement during implantation of WATCHMAN

Background: Although the method of autocalibration or calibration based on catheter diameters was proposed for fluoroscopic measurement during percutaneous left atrial appendage occlusion (LAAO), it may be imprecise and lead to mismeasurement. We sought to investigate whether the utilization of the surface steel ball calibration (SSBC) method under fluoroscopy could facilitate the fluoroscopic measurement of the post-implanted WATCHMAN device (Boston Scientific Corporation, Natick, MA, USA) in LAAO.

Methods: This retrospective study included 97 consecutive patients who underwent percutaneous LAAO with the WATCHMAN device. The SSBC method and sheath calibration method under fluoroscopy, and transesophageal echocardiography (TEE) were employed to measure the diameter of the post-implanted device during the LAAO procedure. The results of the three methods were then compared.

Results: The success rate for procedural WATCHMAN implantation was 100 %. The mean maximal diameter of the post-implanted devices was 24.7 ± 3.1 mm, 23.5 ± 3.2 mm, and 24.2 ± 3.0 mm, as measured by the SSBC method, sheath calibration method, and TEE, respectively (all p < 0.001). The relevant coefficient of correlation between the SSBC method/TEE, SSBC method/sheath calibration method, and TEE/sheath calibration method, was 0.94, 0.93, and 0.89, respectively (all p < 0.001).

Conclusion: The SSBC method, when employed under fluoroscopy, demonstrated a high correlation with the sheath calibration method and TEE for measurements. It may be applied to facilitate fluoroscopic measurements during percutaneous LAAO procedures.