COMPLICATION

Complication

What's another bad scenario for WEB embolization? It's prolapse with occlusion of adjacent branches! Check what Jean-Christophe Gentric and Guiseppe Lanzino will do!

Tips & tricks to safely deploy a WEB and to deal with branch protrusions:

• Before detaching a WEB device, always ensure that you have removed the forward pressure on the device before detachment. If you detach without reducing the tension and pulling gently on the device, you may be in a situation in which the WEB is contracted by the microcatheter, and upon detachment, it will assume its natural form and protrude in one or both branches if it is slightly oversized.
  
• WEB is a nitinol device, so even if you manipulate it after the manipulating force is retrieved it will assume its resting state form.
• WEB shouldn’t be used in recanalized aneurysms because of poor outcomes, as well partially thrombosed aneurysms may not be a good indication for WEB since it will get flattened and absorbed inside the thrombus. If you plan to use WEB with partially thrombosed aneurysms you should always plan on using adjunctive stents to change the angle of the bifurcation and provide some flow-diverter effect. Thrombosed aneurysms are neither a good choice for clipping as you risk mobilizing the thrombus inside the parent artery resulting in ischemic complications during the procedure.
  
  
• In case of improper deployment and device protrusion, two strategiesare feasible:
  1. Retrieve the device using a snare, especially if the tip of the WEB points towards the parent artery. However, this strategy is technically more demanding, and if the aneurysm is also thrombosed, this may result in retrieving thrombus and causing distal emboli.
     
     
  2. Stenting of the branch that is affected by the protrusion:
     • Try to catheterize this branch with a microcatheter;
     • You have the option of using either open-cell laser cut stents or braided stents, with advantages and disadvantages for both:
     • Laser-cut open cell stent: 
       • Reasonable radial force, may compress most slightly oversized WEBs but may prove difficult to compress dangerously oversized WEBs.
       • Easily recrossed towards the other branch if you think Y-stenting will be necessary due to the severity of the protrusion.
       • Less metal theoretically reduces thrombogenicity;
     • Braided stent:
       • Theoretically, it has less radial force, but in face of a severely oversized WEB, you can partially deploy and recapture if you do not obtain a good result;
       • You may and should use shouldering during deployment;
       • Probably indicated if you do not plan Y-stenting, as crossing a braided stent (like LVIS EVO) will be more difficult, and it would add much more metal to the MCA bifurcation;
       • You can easily repass inside and use balloons if necessary;
     • In case of failure to open the WEB and save the branch, consider coronary balloon-mounted stents as a bail-out;

• When you decide to bail out a protruded WEB with a stent in the branch that it partially occludes, you should anticipate that the radial force of the stent will push the WEB. It might impact the other branch, so it is reasonable to put a microcatheter in the accessible branch before you detach the first stent, to anticipate another complication.
• It is not uncommon in patients where you can see an immediate great result and thrombosis of the sac, to have thromboembolic complications, and you may keep the overnight under heparin. 
• You should prepare all your prepares to face every situation.