In 2012, an estimated 259,000 patients were implanted with IVC filters.
Inferior vena cava filters are used in many patients at risk of pulmonary embolism. Inserted using a catheter, the small cage-like devices can be placed inside the inferior vena cava (IVC), a large vessel transporting deoxygenated blood from the lower body on its return trip to the heart.
Clinging to the vessel’s walls using several wire “struts,” IVC filters act as a net, capturing blood clots before they reach the lungs.
Filter Risks: Fracture, Perforation & Embolization
But IVC filters present a number of severe risks, most of which actually result from device failure. Although early, “permanent” models hit the American market in 1979, a “new generation” of IVC filters has been linked to a far higher rate of significant side effects than their predecessors.
A US Food & Drug Administration safety warning, published in light of an alarming number of adverse event reports involving IVC filters, first alerted the health community and patients to the device’s dangers.
Between 2005 and August 2010, the FDA received a total of 921 reports of adverse events connected to the failure of newer “retrievable” IVC filters which, unlike earlier versions, can be removed. Of these reports:
- 35.6% involved filter migration
- 15.9% involved embolization of fractured device components
- 7.6% involved perforation of the inferior vena cava
- 6.1% involved filter fracture
The FDA did not report on the remaining 34.8% of adverse event reports, although its warning announcement highlighted an additional risk: IVC deep vein thrombosis.
While many of the devices are now designed to be removed after a patient’s risk of pulmonary embolism decreases, sources including the FDA have reported that many physicians are leaving IVC filters in for too long. The risk of device failure is believed to increase over time.
Migration & Embolization
“Migration” occurs when an IVC filter detaches from the vena cava’s walls. Carried by the flow of blood upward through the body (most IVC filters are implanted slightly lower than the kidneys), the device’s struts can perforate vessel walls, other tissues or enter the heart entirely.
“Embolization” is an alternative term for “migration,” describing any instance in which a detached mass capable of blocking blood flow travels through the bloodstream.
In little more than five years, the FDA received 328 adverse event reports involving filter migration, spurring the agency to instruct surgeons to remove retrievable filters “as soon as protection from PE
Why Do IVC Filters Migrate?
Several teams of researchers have suggested that the possibility of migration may be “built in” to new-generation IVC filters.
While older models were made of stainless steel or titanium, new retrievable IVC filters come in a variety of cutting-edge alloys with “shape memory.” In colder temperatures, the filters become flexible. When heated, they return to their original shape. Thus fluctuations in body temperature can alter an IVC filter’s configuration, allowing it to detach from the vena cava and flow “upstream.”
Potential Complications Of Migration
In this 2009 report, cardiologists at Michigan’s William Beaumont Hospital described the case of a 54-year-old man whose retrievable IVC filter migrated from below his kidneys to the heart. Eventually, the device entered the patient’s right ventricle, one of the heart’s pumping chambers.
He suffered ventricular tachycardia, an abnormally rapid heart rate, and was subsequently diagnosed with non-Q-wave myocardial infarction, a less severe form of heart attack. A “percutaneous” solution, in which surgeons access internal organs through a single needle puncture, was proposed first but abandoned when it became clear that the IVC filter’s struts had become “intertwined” with tissues of a heart valve.
Ultimately, open-heart surgery was successful in removing the migrated IVC filter.
Symptoms Of Migration
Reviewing relevant medical publications between 1998 and 2008, the researchers found that a majority of patients in whom migration had occurred suffered immediate symptoms, including:
- chest pain,
- fainting (or “syncope) and
- abnormal heart rhythms.
Additionally, patients with migrated IVC filters were considered at high risk for serious complications like ventricular arrhythmia (a common precursor to heart attack) and cardiac tamponade, a potentially fatal medical emergency in which blood escapes into the gap between the heart muscle and the organ’s outer layer.
IVC filter struts can break off and migrate themselves, threatening cardiac tissue and heart function.
Among the FDA’s 2005 to 2010 adverse event reports, 202 involved filter fracture; in 146 of these patients, broken device components managed to “embolize,” flowing along with blood toward the heart.
How High Is The Risk Of Fracture?
Recent findings have suggested that the risk of strut fracture is extremely high.
In 2010, cardiologists at Pennsylvania’s York Hospital examined 80 patients who had received IVC filters manufactured by C.R. Bard, a New Jersey company that now faces at least 25 IVC filter lawsuits. Their results, published in the Journal of the American Medical Association, were troubling:
- In 16% of these patients, at least one strut had fractured.
- In 25% of patients with Bard’s now-discontinued Recovery Filter System, at least 1 strut fragment had embolized, beginning to flow toward the heart.
- In 71% of the patients with an embolized fragment of Bard’s Recovery filter, the broken strut had entered the heart.
- 43% of these patients suffered “life-threatening symptoms,” including one case of sudden death.
When IVC filters fragment, the disseminated pieces are difficult to extract.
In this study, conducted by radiologists at Penn State’s Heart and Vascular Institute, identified a 12% fracture rate among 63 patients implanted with Bard IVC filters. Unfractured, the devices were successfully removed in 98.4% of cases. After breakage, the pieces could only be retrieved in a little over 50% of patients.
While we may feel “still” at any given moment, our internal systems are in constant motion: blood flows ceaselessly; the respiratory system expands and contracts more than 20,000 times a day. Under these normal conditions, IVC filter struts can gradually erode and eventually puncture the inferior vena cava.
The FDA reported 70 adverse event reports in which some degree of perforation had occurred between 2005 and 2010.
“Rule Rather Than Exception” For Long-Term Filter Implantation
The severity of perforation appears to be a direct result of a filter’s “indwelling” time, the amount of time it remains in a patient’s body.
Out of 50 patients with Cook Medical IVC filters, researchers at UC San Francisco found that 86% experienced perforation of the vena cava between 1 and 880 days after filter placement.
Taking CT images of each patient at regular intervals, the team noted that perforation appeared “progressive,” increasing in severity over time. However, every patient exhibited a degree of perforation after only 71 days.
The paper, published in 2012’s Cardiovascular & Interventional Radiology, suggested that IVC perforation was the “rule rather than exception,” at least for Cook Medical’s devices. Elsewhere, the risk of perforation has been estimated at anywhere between 9% and 24%.
Organs & Tissues At Risk
Once a strut has managed to puncture the vessel wall, the sharp wire can pierce surrounding tissues and organs. Since IVC filters are almost universally placed near the kidneys, damage most often occurs to the intestines and ureter, along with other nearby blood vessels. Cases in which an errant strut harms the spinal column or diaphragm are not unheard of.
Many case reports describe filter struts that have managed to puncture a patient’s duodenum, the small intestine’s uppermost chamber.
In 2001, surgeons at the University of Florida reported the case of a patient in whom two struts had punctured the vena cava, one piercing the small intestine while the other threatened to perforate a major blood vessel. The patient’s symptoms included abdominal pain, nausea, anorexia, and constipation. He lost 40 pounds due to the IVC filter’s intestinal penetration.
In this report, Brazilian vascular surgeons described the case of an IVC filter that had perforated the vena cava and gone on to dig its hooks into the patient’s descending aorta, the body’s largest artery.
Complications Of IVC Perforation
The primary complications associated with IVC perforation are:
- Retroperitoneal hematoma – a swollen clot of blood within body tissues of the abdominal cavity
- Sepsis – a complication of infection and potentially life-threatening emergency. In sepsis, the body reacts to an infection by releasing chemicals into the bloodstream, which trigger inflammation throughout the body. Sepsis can lead to systemic organ failure, shock, and death.
- Gastrointestinal bleeding – even minor amounts of bleeding in the GI tract can result in long-term complications like anemia and low blood counts, according to the US National Library of Medicine.
Any form of “thrombosis” is characterized primarily by a localized clotting of blood somewhere in the circulatory system. Intuitively, inferior vena cava thrombosis refers to the formation of a clot in the IVC, a blockage that limits the flow of deoxygenated blood on its journey back to the heart.
In its initial safety warning, the FDA listed “lower limb deep vein thrombosis” under the IVC filter’s known long-term risks. While it may seem perverse that these devices can cause a condition they were designed to treat, a long history of medical research has associated filters with an increased risk for potentially life-threatening blood clots.
Notably, this general review of the condition pointed to a causal link between “pathological changes in the vessel wall,” such as filter perforation, and IVC thrombosis. Publishing their article in Vascular Medicine, the authors wrote: “placement of foreign bodies such as IVC filters […] may promote” the development of new blood clots.
From 1973 to 1998, radiologists at Massachusetts General Hospital followed the progress of 1,731 patients with IVC filters. Even following implantation of the device, 3.7% of these patients died of pulmonary embolism; in another 12, pulmonary embolism was identified during an autopsy but considered unrelated to the cause of death.
The researchers also observed a fair number of blood clots forming in the vena cava after a filter’s insertion. In total, 55 patients developed IVC thrombosis; 87% experienced leg edema, a painful swelling of the lower body.
Symptoms & Risks Of Blood Clots In The Inferior Vena Cava
IVC thrombosis is widely considered a subtype of deep vein thrombosis, or DVT, since the IVC is considered a “deep vein,” one lying far from the skin’s surface. Inhibiting blood flow, a clot in the IVC often causes:
- painful swelling in the legs
- lower back pain
The potential complications of IVC thrombosis are highly variable; some patients may remain asymptomatic, experiencing no ill effects, while some undergo complete cardiac collapse.
Like any form of DVT, IVC thrombosis can result in pulmonary embolism, in which the clot breaks free of its starting point and is carried into the lungs.
Patients Who Suffered Side Effects May Be Eligible For Compensation
In light of the health community’s widespread acknowledgment of IVC filter failure and its significant risks, injured patients have begun to file lawsuits. More than 100 claims have been brought against C.R. Bard and Cook Medical, the primary manufacturers of these dangerous medical devices.
Visit our “IVC Filter Lawsuits” to learn more about settlements, class actions and the progress of this ongoing litigation.
In court documents, Plaintiffs accuse the IVC filter industry of concealing the device’s serious risks for decades, while promoting a product with no proven clinical benefits. They say companies like Bard and Cook marketed a defective device to generations of physicians and patients.
Many more lawsuits are expected in the coming months, and you may have a case.
If you suffered severe side effects as a result of IVC filter migration, fracture, embolization, perforation or thrombosis, contact the experienced attorneys at Banville Law today. We’re currently offering free consultations to patients interested in learning more about their legal options. For a no-cost case eligibility evaluation, call or complete our contact form.