IVC Filter Removal
IVC filters are meant to catch blood clots before they can damage the lungs and potentially kill a patient. But putting the devices into a patient’s vein, and later removing it, presents risks of damage to blood vessels and other serious complications.
IVC filters are small, cage-like devices designed to fit inside the body’s largest vein — the inferior vena cava (IVC). IVC filters are usually put in place using a long tube called a catheter that is threaded through veins or arteries. The filters are designed to catch and hold blood clots in place and allow them to dissolve naturally before the clots can cause damage.
Older IVC filters were meant to be left in place. Newer designs, called retrievable IVC filters, should be removed once the danger of clotting is over, according to the Radiological Society of North America.
A procedure similar to the one used to implant the filters is used to remove them.
But removing the devices presents risks. The procedure may damage blood vessels, break filters or cause other complications. Or they may have become embedded in the wall of a blood vessel requiring advanced filter retrieval procedures.
“Patients should educate themselves and be aware they might be candidates for filter removal. And if so, it ideally should be done in a center that has the appropriate experience,” Dr. William Kuo, an interventional radiologist at Stanford Health Care, told Drugwatch.
Dr. Kuo pioneered a laser-assisted advanced IVC filter removal procedure that he and his colleagues perform hundreds of times every year. It is used for filters that cannot be removed conventionally.
How Are IVC Filters Removed?
Doctors remove retrievable filters in a way similar to how they implant them. Health care providers inject contrast or X-ray dye around the device to make sure it is safe to proceed with the removal. A catheter-like snare goes into the vein and grabs a hook located at the end of the filter. A sheath covers the filter, collapsing its legs and releasing its grip on the vein’s walls. The doctor then pulls the catheter out of the vein, bringing the IVC filter with it.
What to Expect Before Removal
The FDA recommends that retrievable IVC filters should be removed once the danger of a pulmonary embolism has passed. This can be accomplished in most patients through anticoagulation treatment – the use of “blood thinners” such as warfarin. If a patient suffers from pulmonary embolism (PE) or deep vein thrombosis (DVT) and cannot take an anticoagulant, the IVC filter may be left in place.
“The FDA recommends that implanting physicians and clinicians responsible for the ongoing care of patients with retrievable IVC filters consider removing the filter as soon as protection from pulmonary embolism is no longer needed.”
Patients Checked Before Procedure
In the weeks leading up to filter removal, doctors reassess their patient’s requirements.
- Ultrasound for patients with no known DVT to confirm they don’t have it
- Two to three weeks of anticoagulation treatment for those at DVT and PE risk
- Anticoagulation therapy can continue prior to the removal
Preparing for Removal
Before undergoing an IVC filter removal, patients should go over their medical history, including any current illnesses or medical conditions, with their doctor. Patients should report all medications and herbal supplements they are taking as well as any allergies, especially to drugs or anesthesia.
- Eat only a light meal the night before
- Avoid food and drink after midnight before the procedure
- Adjust their insulin dose if they are diabetic
- Wear a hospital gown and remove all jewelry for the procedure
- Have someone to drive them home after the procedure
Any surgery carries risks. These can include infection or reaction to the drugs used during the procedure. In addition, IVC filter removal procedures carry their own complications.
- Blood vessel perforation
- Difficult retrieval causing long surgery times
- Damage to the filter
- Inability to remove the IVC filter
Research has shown that roughly 80 percent of IVC filters can be removed, but there are some cases where they have to be left in the body.
- The filter has filled with blood clots
- Incorrect dose of blood thinner
- Scars in the vein attach to the filter and prevent removal
If a filter cannot be removed, the patient may have to consider a second surgery or leave the device in. Blood thinner dosages may have to be adjusted before any further surgery, but if the filter has grown into the vein’s scar tissue, removal becomes increasingly complicated. Advanced surgery centers may be able to use a laser to remove some of these devices.
In this procedure, a laser is inserted inside the catheter and sheath that would normally remove the filter. The laser burns away the scar tissue until the filter can be collapsed, collected in a sheath and removed with the catheter.
What Happens If a Retrievable Filter Stays in Place Too Long?
Studies have shown that the longer a retrievable IVC filter remains in place, the more difficult it is to remove.
“A filter sitting in a vein for a long enough time will cause scar tissue to form around it and eventually, the device becomes ingrown and embedded in the vessel,” Dr. Kuo said.
It may also increase the risk of complications such as vein perforation, the filter breaking or broken parts reaching and damaging the heart, lungs or other organs.
Blood clots are the body’s natural response to stop bleeding. Doctors may implant IVC filters after a major surgery or accident that triggers this clotting response because they may believe a patient is at risk of suffering a pulmonary embolism. The FDA recommends retrievable filters be removed as soon as the clotting risk is over, usually after just a few weeks. But many are left in place for years.
Embedded IVC Filters
In some cases, IVC filters left in place long-term cannot be removed because they embed themselves in the walls of the vein.
“Unfortunately, this complication can be really high,” Dr. Kuo told Drugwatch.
“Some reports in medical literature estimate 20 to 40 percent of cases or more and it also depends on how long the filter has been in and what make and model the filter is,” he said.
Doctors have begun developing specialized procedures to deal with difficult-to-remove filters. In the past, they often had to improvise retrieval methods.
Illinois doctors Benjamin Lind and Hector Ferral documented a case in which they successfully removed a Cook Medical Günther-Tulip IVC filter more than nine years after it was implanted. The device had shifted, penetrating the wall of the vein and perforating the patient’s small intestine and part of her urinary tract.
Extensive Removal Planning
Because the device had been left in the patient for so long, removing it required extensive planning and a unique procedure.
“A considerable amount of endovascular experience is required to remove these filters,” the doctors wrote in the Journal of Vascular Surgery Cases. “The key to the present case was careful planning.” The doctors used multiple instruments to dislodge the filter only to find that its prongs had become attached to the wall of the vein. They finally had to insert and partially inflate an angioplasty balloon, used for heart procedures, into the vein. The doctors partially inflated the balloon on one side of the IVC filter while continuing to pull on the device from the opposite side. After considerable work, they were able to successfully remove the filter.
But in some cases, doctors have had to perform open surgery, actually cutting the patient open to remove the filter, and sometimes the vein around it as well.
Advanced IVC filter retrieval involves cases in which the standard technique — using a snare to retrieve the filter — can’t be used.
“A lot of patients and even their doctors don’t know that advance filter retrieval techniques can now be done without the need for open surgery,” Dr. Kuo told Drugwatch.
Dr. Kuo pioneered a minimally invasive IVC filter retrieval procedure that uses an excimer laser. These are lasers used for extremely fine work, such as making semiconductor circuits or micromachining. Medical uses include delicate eye surgery.
“The idea behind the excimer laser is to help deal with scar tissue that forms around a filter,” Dr. Kuo said.
The laser emits concentrated, ultraviolet light at its target, firing in bursts as short as one-billionth of a second. In eye surgery it may be used to vaporize part of the cornea’s surface, reshaping the eye to correct the patient’s vision.
Dr. Kuo and his Stanford team use the laser to target the scar tissue in which an IVC filter has become embedded. They remove tiny layers of scar tissue, each 60 to 100 microns thick — between 2 and 4 one-thousandths of an inch — at a time. Once the scar tissue is removed, the filter is usually retrievable.
“We have found that this has really opened up possibilities for removing long-term ingrown filters that were previously considered irretrievable,” Dr. Kuo said.
An article in the January 2015 issue of Vascular Disease Management identified several other advanced IVC filter retrieval procedures. Authors from the University of Miami School of Medicine and Jackson Memorial Hospital in Miami based their paper on procedures they’d performed at their institutions.
- Stiff-Wire Displacement
- Used if the filter has shifted and the tip is against or embedded in the vein wall. A stiff wire is passed between the filter tip and the wall to reposition it so it can be retrieved using a snare.
- Balloon Displacement
- An angioplasty balloon is passed through a catheter to the filter hook and inflated. This can sometimes loosen the embedded filter, but it may have a higher risk of causing a filter fracture or causing it to migrate to another part of the body.
- “Sandwich” Technique
- This requires going into the inferior vena cava from two different directions, engaging both the tip and the tines at the end of the filter’s legs. Once loosened from the vein walls, it can be removed with the typical snare removal method.
- “Telescopic Sheath” Technique
- It also approaches the filter from two different directions like the sandwich method. Two retrieval sheaths are deployed, entering the large femoral artery in the thigh — a smaller one toward the tip from above and a larger sheath from below. The twin sheaths completely encase the filter and are removed through the entry incision in the femoral artery. This prevents the filter from redeploying if there’s a risk it can’t be fully encased in a single sheath removal.
- “Sling” Technique
- This is usually used for non-conical shaped filters. A doctor routes a guidewire into a U-shaped sling around the middle of the filter. Gentle pressure is applied to both ends of the wire and the snare to loosen an embedded filter.
Please seek the advice of a medical professional before making health care decisions.