The body has amazing survival mechanisms to keep us alive. In the case of trauma, a blood clot can form around a blood vessel that has been damaged during trauma from an accident.
A blood clot can also form when cholesterol plaques break apart and travel in the artery. They too can mimic a trauma and the clotting process starts.
If a clot forms in the deep veins of the legs, arms or pelvis it is called Venous Thromboembolism (VTE), also known as Deep Venous Thromboses or DVTs. You’ve heard of this condition if a patient stays on an airplane too long and doesn’t move. A DVT can travel up the blood vessels and get into the heart or lungs where it can cause a heart attack or a pulmonary embolism (PE).
Either way, there is an interruption of normal blood flow to the body which can be life-threatening.
With this condition, your doctor will prescribe blood thinners. Their anticoagulation ability can break up a clot until it dissipates on its own. Also, an IVC filter may be placed in the inferior vena cava (IVC), the body’s largest vein, to trap the blood clot as it moves up from the lower half of the body.
Some patients are unable to take blood thinners and an IVC would then be the first line of defense. Others need the additional security of an IVC filter.
Made of a metal alloy of nickel and titanium (nitinol), an IVC filter is generally about an inch-and-a-half long and resembles a badminton birdie with dangling metal legs. In an ideal world, it works well. The filter is placed by a vascular surgeon or interventional radiologist with just a small incision placed in the jugular or groin. A catheter guides the filter into place with the help of an x-ray. The removal process is the same in reverse. A catheter delivers a snare to catch the hook at the end of the filter and pull it through the removal sheath.
Initially it was thought some of these filters should be implanted permanently but in 2010, the U.S. Food and Drug Administration changed that position and said most should be out before the 54th day after implantation and when the danger of PE has passed.
Today about 250,000 IVC filters are implanted in Americans every year.
But with the passage of time, we are learning more about IVC filters and questions are long overdue as to whether the benefits exceed the risk, especially since some manufacturers have more problems than others.
Especially problematic is the Recovery and G2 IVC filter made by C.R. Bard of Murray Hill, New Jersey. The FDA warning to remove the filters and not leave them in permanently came after the FDA received 921 reports of adverse events of complications, many with the Bard devices.
In a November 2010 published report, from York Hospital at Penn State College of Medicine, a prevalence of fractures and fragmentation implicated the Bard IVC filters.
Thirteen of 80 patients in this retrospective, cross-sectional study of patients with Recovery or G2, had at least one strut fracture of the delicate IVC filter legs. One strut in seven fractured and embolized or blocked the passage of blood. In five of these cases, at least one fragment embolized to the heart. As a result, three patients experienced symptoms of ventricular tachycardia, an elevated heart beat that can preclude a heart attack.
One patient had to undergo emergency open-heart surgery to remove the fragments of the filter.
One patient died at home. Even with that, researchers say the traveling to the heart of a strut fragment is a “rarely reported occurrence,” which of course doesn’t matter if it happens to you.
The research found the Recovery filter had a 25 percent prevalence of device fragmentation and embolization.
An improvement to Recovery came in September 2005 with the redesigned G2 cava filter. It was supposed to improve resistance to fracture by reducing stress points and using longer filter arms to reduce the load.
Over 65,000 G2s were implanted between September 2005 and 2010 when it came off the market.
The same researchers wanted to determine if G2 had improved outcomes over Bard’s Recovery.
Again, they noted a lower fracture rate than Recovery but still a high tendency to fracture – 12 percent or six out of 52 filters. One fragment rested in the hepatic vein (carries blood away from the liver) and one in the lung. In two cases, the filter fragment embolized the heart and perforated the right ventricle. That patient had life threatening cardiac tamponade (the heart does not get enough blood) and emergency open heart surgery.
Four of the 6 Bard G2 fragmented filters remained near the original device.
Another study in 2009 out of the Vascular and Vein Center of Columbus, Ohio, looked at two cases. A 27-year-old who could not take warfarin as an anticoagulant and instead received an IVC filter. At the ten-month mark, he had a complaint of nausea and vomiting some blood and discomfort. A CT scan showed the inferior vena cava pierced by one of the filter prongs. It had to be cut out with wire cutters. He was okay and discharged from the hospital.
A 61-year-old woman went to the emergency room with nausea, shortness of breath and chest and abdominal pain. She had a G2 IVC filter and several prongs penetrated the IVC wall but she did not undergo surgery because a CT scan showed the filter was stable, even though several prongs were extending outside of the vein.
The Ohio study found among the G2 filters, 3.4 percent had fractured prior to removal at 180 days.
According to a May 6, 2014, FDA Safety Communication, the agency has received reports of vein and organ perforation with the IVC filters upon placement, while it remains in the body, and during retrieval, yet we know about half of IVC filters that can be removed are not.