Zenith abdominal aortic aneurysm (AAA) endovascular grafts and associated H&L-B One-Shot 를 위한 안전성 경고 / 현장 안전성 서한

Data from the United Kingdom is current through April 2019. All of the data comes from the Medicines and Healthcare products Regulatory Agency, except for the categories Manufacturer Parent Company and Product Classification.
The Parent Company and the Product Classification were added by ICIJ.
The parent company information is based on 2017 public records. The device classification information comes from FDA’s Product Classification by Review Panel, based on matches of recall data from the U.S. and the United Kingdom.

Potential for serious injury or death of the patient due to difficulty releasing or inability to release the suprarenal stent during graft deployment.MHRA has received reports relating to complications experienced during attempts to release the topcap and deploy the suprarenal stent (top-stent) in a number of Cook Zenith AAA endograft procedures. These have involved difficulties releasing or inability to remove the proximal black trigger-wire, delaying or preventing the release of the top-cap and the associated deployment of the enclosed top-stent.Cook Zenith endovascular grafts have unique proximal and distal trigger-wire release mechanisms. The purpose of the proximal black trigger-wire is to prevent the premature release of the barbed top-stent held within the top-cap of the H&L-B One-Shot Introduction System. The trigger-wire passes through a single hole in the top-cap and through one of the top-stent ‘stent eyelets’ constrained within it. Once deployed, the top-stent is designed to provide physical radial pressure on the aortic wall and stability for the AAA endograft device, minimising the risk of distal migration.Deployment of this device is a multistage procedure. When the proximal trigger-wire is about to be removed, the endograft is already in a partially deployed condition and it is no longer possible to re-sheath or remove the device from the patient.Although the worldwide incidence of trigger-wire or top-cap release problems with this introduction system since 2003 remains low (below 0.1%) these have included serious patient complications such as conversion to open surgery, permanent injury or subsequent patient death.The following factors appear to give rise to difficulty in removing the proximal trigger-wire:inadvertent upward movement of the top-cap in relation to the top-stent during insertion and manipulation of the introduction system may raise tension on the trigger-wire, thereby temporarily entrapping it and increasing the potential for wire deformation;
the tension between the entrapped trigger-wire and the top-cap may be amplified further if an operator pulls downwards on this trigger-wire in an effort to free it, possibly leading to added deformation of the trigger-wire. Similarly, undue tension will be applied to the entrapped trigger-wire if the top-cap is pushed forward in an attempt to free the top-stent.Excessive downward force on a deformed, entrapped trigger-wire may also irreversibly alter the shape and position of the proximal end of the inner cannula and dilator tip, causing it to bow. It is important to ensure that the manufacturer’s recommended model and length of stiff guide wire is used and advanced beyond the end of the dilator tip (to the thoracic aorta) to provide maximum support for the inner cannula.Techniques that may help resolve an entrapped trigger wire are described in the ‘Physicians Reference Manual’ (see Chapter 8, pages 126-127). If these techniques are unsuccessful, an alternative deployment sequence is available to resolve the situation (see trigger wire release instructions).Well maintained and high resolution fluoroscopy equipment is essential for troubleshooting during implantation of these complex devices. Good fluoroscopy will also assist in accurately confirming the position of the top-cap in relation to the top-stent.