Kinked Catheter during cardiac catheterization

Knotted Intravascular Catheters and Foreign Body Removal

Knotted catheters, guide wires and electrodes are rare but serious complications of angiographic procedures and line insertions. The percutaneous techniques and materials used in releasing knots are similar to those used in foreign body retrieval. The aim of this review is to provide an overview of both of these important skills.

Managing knotted catheters

Knotting can occur when curved catheters are reformed in the aorta or when excessive manipulation is used to engage a branch vessel such the right coronary artery (1). Head hunter shaped catheters are thought to be particularly prone to knotting (2) as are pulmonary arterial Swan Ganz catheters due their length and flexibility.

In all cases manipulating the knotted catheter at the level of visceral branches should be avoided, as should loosening the knot by fixing the distal tip of the catheter within a branch vessel. Both risk intimal damage and embolisation (2). Almost all methods can be performed in the lower abdominal aorta. Where catheters have more than one knot they should be corrected in sequence starting with the most distal first.

Simple measures

The following may be tried initially:

  • Gentle catheter traction and rotation.
  • Withdrawing the catheter over a stiff guide wire.
  • Advancing the catheter with a stiff wire to fix the loop against the superior aspect of the aortic arch. Gentle to and fro motion of the catheter enlarges the loop and loosens the knot allowing a wire to be advanced (3). This is most effective with a large loop.

These methods may in fact tighten the knot and more challenging cases require counter traction to loosen the knot (2).


Methods requiring a contralateral femoral artery puncture or puncture of a common femoral vein

  • Hooking the loop of a knot with a secondary catheter

A guide wire and pigtail catheter may be passed through the loop of a knot from the contralateral groin. The pigtail can then “lock” in position and traction applied to it while advancing the knotted catheter with a guide wire to loosen it (2). The knot may also be withdrawn to the level of the aortic bifurcation and gentle to and fro traction applied (4). A similar method describes snaring the loop with a side winder catheter. Both catheters are then withdrawn to the aortic bifurcation where the secondary catheter is then closed within the iliac artery making opening of its curve less likely. Traction is then maintained on the secondary catheter while advancing and loosening the knotted catheter (5). Similarly a hooked catheter and deflecting guide wire from the groin may be used to snare the knot of a venous catheter allowing both catheters to be pulled in opposite directions (6).

When small the knot loop may be enlarged by inflating an angioplasty balloon through the loop (7). Alternatively a stiff guide (such as a Lunderquist) passed through the loop of a knot and positioned well above the level of the knot, to provide adequate support, may then allow a knotted catheter to be manipulated and loosened. (6).

  • Tightening the loop of a knot

Tightening the knot makes it smaller. This may be achieved by forcing the knot against a catheter sheath (6) or with venous catheters by snaring the knotted catheter from the groin and pulling on both ends. The tightened knot may then be pulled down to the groin after cutting its hub at the insertion site and removed through an introducer sheath (8).

  • Grabbing the knotted catheter with forceps or snare

Grabbing forceps have been used to fix guiding catheters above the level of the knot. The proximal end of the catheter is then manipulated to free the knot with anticlockwise rotation being most successful (1). Snare devices can be used in a similar manner by fixing the end of central venous catheters

  • Combined percutaneous and surgical removal

Appropriate for large or multiple knots. After pulling down a knotted catheter to a superficial vein, venotomy is performed under local anaesthetic.

Foreign body retrieval

Foreign body retrieval should be undertaken promptly to avoid life threatening complications such as thromboembolism, infection, perforation and arrhythmia (9). Foreign bodies include filters, valves, pacemaker transducers, stents and embolised coils as well as more familiar catheter and guide wire fragments. Retrieval methods are highly effective (10) and the same principles apply for venous and arterial retrieval.

The loop snare is the most effective and commonly used method (10). Baskets and forceps have also been used but are both relatively rigid making tortuous vessels difficult to negotiate (10). Loop snares are directed using a curved guiding catheter such as a cobra or multipurpose catheter (11). Once the fragment is encircled the catheter is advanced to close the loop. The fragment is then fixed firmly against the catheter and ideally withdrawn into the catheter. A larger 9F catheter and / or long sheath is therefore used (11).

Fragments that do not present a free end to the snare first require manipulation or extraction to a larger vessel. Double curve or pigtail catheters, deflecting guide wires with fixed hooks (9), grasping forceps, baskets and balloon catheters have all been used (10,12). A Judkins left coronary artery catheter can be used to hook trapped coronary electrodes, which commonly lies with its tips in the left subclavian vein and right ventricle. The catheter is then pulled to release one end of the electrode which can then be snared (10). A technically demanding co-axial catheter pass over technique has also been described. A guide wire is passed through the catheter fragment. A larger catheter is then passed over the fragment and then withdrawn through the sheath (10).

In conclusion knotted catheters and retained intravascular foreign bodies are important clinical situations which all angiographers will face. Familiarity with the percutaneous management options are essential for a successful outcome and avoidance of surgery.

Here is a kinked catheter in the right common iliac artery

Here is a kinked catheter in the right common iliac artery


During embolisation of an arteriovenous malformation at the left shoulder, a coil has migrated to the right common femoral artery (arrow).

During embolisation of an arteriovenous malformation at the left shoulder, a coil has migrated to the right common femoral artery (arrow).


The coil was retrieved by puncturing the contralateral femoral artery and using a snare device passed across the aortic bifurcation.

The coil was retrieved by puncturing the contralateral femoral artery and using a snare device passed across the aortic bifurcation.


Dr Farhan Ahmed and Dr Ashish Saini
Interventional Fellows
St Thomas' Hospital
London, UK


Dr. Tarun Sabharwal
Consultant Interventional Radiologist
St Thomas’ Hospital
London, UK

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