Cobra catheter

Last revised by Yahya Baba on 11 Oct 2023

The Cobra tip shape configuration is used in selective angiographic catheters and designed for catheterization and subselection of vessels, in order to secure access, advance, exchange devices, or deliver contrast in the target vessel 1.

The Cobra tip-shape configuration is also used in urology renal catheters, for accessing the renal pelvis through cystoscopy/endoscopy.

  • French-Size: 4F or 5F for vascular catheters and 6F for urology catheters

  • recommended guidewire:

    • 0.035″(0.89 mm) for 4F

    • 0.038″ (0.97) mm for 5F

  • length: 65 cm - 100 cm

  • ports (side holes): usually end-hole catheter, but can have two side holes

  • proximal end: Luer lock hub

  • distal tip: may be tapered, there is generally no bumper-tip

It is a double-curved shape, with primary and secondary curves in the same direction.

It comes in different tip-shape configurations:

  • Cobra C1: smooth and continuous curve along its length

  • Cobra C2: similar to the Cobra C1 catheter, but it is slightly longer and has a more pronounced curve

  • Cobra C3: longer than the Cobra C2 catheter

The Cobra catheters are not optimized for steeply angled target vessels. The renal double curve catheter is a better alternative in this case.

  • secure peripheral vascular access

  • flush the catheter and guidewires

  • place the navigation guidewire around the ostium target, bony landmarks could be used as reference

  • advance the catheter over the wire until reaching the tip of the wire.

  • retract the wire to allow the tip of the catheter to form

  • advance the wire in the formed catheter and slightly advance and retract the wire until the target ostium is catheretrised

  • once the wire is in target vessel, advance the catheter

  • once the catheter is in the desired location, deliver the rail guidewire of choice through the catheter

  • maintain access with guidewire while removing and discarding the catheter

To decrease the risk of vascular injury:

  • catheters should always be inserted and withdrawn over wires, as the tip of catheters moving within a vessel can cause dissection

  • always verify the catheter pressure rate limit while using the power injector since surpassing these thresholds can damage both the catheter and the blood vessel

  • in case of resistance while advancing or withdrawing the catheter, it is important to stop and identify the underlying cause of the resistance before proceeding further

  • avoid bending or kinking the catheter before its placement, as doing so may damage the catheter and lead to injury for the patient

  • in a setting of catheter exchange, to avoid sheath catheter thrombus migration, an aspiration through the sheath catheter should be performed before insertion of the new catheter

The loop technique is employed to reverse the curve of a braided Cobra catheter, allowing for catheterization of upward vessels like the left gastric artery 2.

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