Nonsurgical Retrieval of Devices and Foreign Bodies

Interventional procedures for removing malfunctioned, fractured, or migrated devices.

By Kenneth R. Thomson, MD, FRANZCR
 

Interventional procedures to retrieve devices and other foreign objects from within vascular spaces are useful additions to the skill set of endovascular specialists. These objects have been previously classified as long and skinny and round and slippery.1

Every endovascular specialist will, at some time or another, be confronted with the problem of a device that has malfunctioned, fractured, or migrated and requires removal. Coronary artery stent migration and subsequent retrieval are the most commonly reported device misplacements because these are the devices most commonly used, but the incidence is still less than 0.5%.2,3 Some of the devices physicians may encounter are listed in the Classifications of Intravascular Foreign Bodies sidebar. The reasons for migration of devices are numerous, but the most common is a misjudgment of the relative size of the device and the intended site of placement. Coronary stents are the exception because these are mostly dislodged by calcified plaque before or during placement. Different methods of retrieval are needed for each type of object. This article discusses methods for nonsurgical foreign body retrieval. In some cases, it is better not to attempt to remove the device but to render it harmless in situ.

RETRIEVAL DEVICES
There are many kinds of commercially available snares and graspers for retrieval. However, it is easy to make a loop snare with a standard 5-F angiographic catheter and a 180-cm, 0.018-inch guidewire (Figure 1). This is our most commonly used snare. Mallmann et al4 reported 100% success using this type of device, but its usefulness was well known before this recent publication. The advantages of this type of snare are that it has a variable size loop and that it is inexpensive. If the end of the loop is kinked with forceps, this snare can be deflected to either side more predictably. The other advantage is that the angiographic catheter has a shaped tip (most commonly a Hinck or Cobra 2 shape) and, usually, better translational torque than a commercial snare.

Commercial devices include 0.038-inch single-arm forceps, snares, and graspers for inferior vena cava (IVC) filter removal, stone retrieval baskets, and loop snares designed for embolization coil retrieval. There are several cleverly designed forceps and graspers for laparoscopic use, but they are generally too short, rigid, and large in terms of caliber for endovascular use. Although the concept of grasping forceps is attractive, in most cases, it is easier to grasp the wall of the cavity or vessel rather than the foreign body itself.

In small tubes such as the bile duct or ureter, commercial stone baskets or a simple balloon catheter are effective. In the case of the bile duct, a stone just needs to be ejected into the duodenum. Ureteric stones can be delivered through a nephrostomy or per urethra. Most of the foreign bodies in the airways and upper alimentary tract are removed endoscopically without the assistance of endovascular specialists. Urethral foreign bodies usually damage the posterior urethra. This subject was reviewed by Forde et al.5

A loop snare can also be used for capture and change of double-pigtail ureteric stents via nephrostomy or urethra. It is important to position the snare close to the tip of the double-pigtail stent. Once the stent tubing is externally visible, a guidewire is passed through the stent to allow replacement with a new stent, if that is required.

For larger devices within body cavities, most commonly the rectum, a four-wire snare allows better control for round and slippery objects. Most of the commercial fourwire devices are too short or rigid for intravascular use.

METHODS
In almost every case, it is possible to remove the unwanted object without resorting to an open operation. In some cases, a large or rigid object can be captured and brought to a superficial site where simple surgical removal under local anesthetic is possible. Occasionally, intracardiac devices, such as stents and filters, may damage the tricuspid valve if they become entangled during migration6 or retrieval, and in these cases, a surgical approach from the right atrium is preferable.

The best time to remove a device is as soon as possible after it becomes unwanted. An unwanted device becomes a foreign body and a possible source of patient complications. This axiom applies to IVC filters as well as other devices. Intravascular objects become covered by endothelium surprisingly quickly, and if the foreign body becomes incorporated with the vessel wall, it may not be possible to engage or remove it without causing significant endothelial damage.7 In the case of large-caliber devices such as atrial septum occluders, there is a risk of aortic or large branch vessel thrombosis, and usually, open or laparoscopic surgery is required.8

It is not uncommon to see pieces of IVC endothelium attached to long-dwelling IVC filters after retrieval. This is most marked with filters that have closed sections in contact with the IVC endothelium (Figure 2). We have seen a retained guidewire, which was inserted in the subclavian vein during a resuscitation, that appeared in the iliac and femoral veins. The patient presented with a piece of the guidewire mandrel projecting from his calf. Endovascular retrieval failed, and at surgery, the guidewire was completely incorporated within the vein wall. It could not be retrieved without transecting the femoral vein.

Sections of silicone catheters from venous access devices may also become closely applied to the wall of the pulmonary artery and cardiac chambers. This makes it difficult or impossible to engage the tubing with a conventional snare. In this situation, provided the tubing is flexible, a catheter can be passed beneath the tubing near a less fixed portion and a snare used to complete the capture (Figure 3).

The steps in removal are deciding what to capture the foreign body with, positioning the retrieval system, engaging the foreign body, and bringing the retrieval device and foreign body to the retrieval system’s point of entry. It is very important to consider how the foreign body is engaged, because it may not be possible to extract a long and skinny object that will not bend easily unless it is captured near one end (Figure 4).

Consideration should be given to the delivery method of the foreign body. It may be easier to pull a stent or catheter through the tissues to the puncture site than to insert a very large access sheath. For extravascular foreign bodies, a combination of fluoroscopy and computed tomography may be helpful.9 If “bare” delivery is planned, the access site should be enlarged so that forceps can be used to ensure that the foreign body is not lost at the access site (Figure 5).

As an alternative to removal, a misplaced stent can be repositioned where it will be innocuous. The final resting place should be where branch vessels are not compromised and the stent can be securely fixed without the risk of further migration (Figure 6).

CONCLUSION
Endovascular retrieval of foreign bodies and misplaced devices is a simple technique, and there is a large array of instruments available for this purpose. For most situations, a simple loop snare is as effective and at a far lower cost than commercial snares. In most cases, open or even laparoscopic surgery can be avoided. It is important to remember that although no job is too small, some jobs are too hard. In the latter case, the interventionist can always either leave it alone or resort to open surgery.

Kenneth R. Thomson, MD, FRANZCR, is Professor and Director of Radiology, Alfred Hospital, Monash University in Melbourne, Australia. He has disclosed that he holds no financial interest in any product or manufacturer mentioned herein. Dr. Thomson may be reached at +61 3 9076 2536; k.thomson@alfred.org.au.

 

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