Differences between manufacturer-specified and measured effective inner diameters of vascular introducer sheaths: a micro-CT analysis

Purpose: To quantify deviations between the inner diameters specified by manufacturers and the effective diameter of vascular introducer sheaths.
Materials and methods: A total of 18 different introducer sheaths (one device per type) with nominal inner diameters (nID) of 5 French (Fr), 6 Fr, and 7 Fr and lengths of 10 cm, 25 cm, and 45 cm, manufactured by four different vendors (Terumo, Biotronik, Merit, and Cook Medical) were evaluated. Non-destructive testing was performed using a commercial Micro-CT system (Comet Yxlon) at three distinct anatomical locations: the hub, middle, and tip/aperture. Cylindrical and circular least-squares fits were applied to calculate the effective inner diameters (eID). The eIDs were compared with the inner diameters specified by the manufacturer (mID) and the nominal inner diameter (nID) in Fr, which both are regularly mentioned for each product.
Results: All non-braided sheaths revealed eIDs at the hubs, middles, and tips exceeding the mIDs (up to + 8.5%). All eIDs at the sheath aperture were consistently smaller than the mIDs and, with one exception, smaller than the nID. For braided sheaths, most eIDs at the hub were up to 3.4% larger than specified. However, at the tips and the apertures all braided sheaths were smaller than the mID (up to − 10.99%). In comparison with the nID, most braided sheaths were larger.
Conclusion: Relevant deviations exist between the effective and manufacturer-specified inner diameters of vascular sheaths, especially at the tips. These discrepancies may necessitate the selection of larger sheath sizes to accommodate specific interventional devices, particularly when aperture constraints are critical.