An inferior vena cava filter ( IVC filter ) is a type of vascular filter, a medical device implanted by an interventional radiologist or a vascular surgeon into the inferior vena cava to possibly prevent pulmonary embolism which is life-threatening (PE). Their effectiveness and safety profiles are not well established, and in general, they are only recommended in some high-risk scenarios. They are not intended to be a substitute for the management of vein thromboembolic (VTE) medical (drug-based). However, in cases where high-risk patients develop clinically significant PE and not enough anticoagulants, IVC filter placement may be recommended.
To date, only one randomized controlled trial has been completed on the IVC filter. The study found that IVC filters reduced the incidence of PE but increased the incidence of deep vein thrombosis (DVT). All patients took anticoagulant medications during the study. Results from the PREPIC study and other studies that have demonstrated many long-term complications of IVC filters led to the introduction of IVC filters that could be taken. The first approved IVC filter was approved by the FDA in 2003 and 2004.
In 2012, the American College of Chest Physicians recommend IVC filters for those who have contraindications to anticoagulation that also have acute PE or deep deep acute (deep knee) deep thrombosis (DVT).
Video Inferior vena cava filter
Histori
The first IVC filter was made by Kazi Mobin-Uddin, MD who published his findings in the New England Journal of Medicine. The Mobin-Uddin filter was later replaced by a Greenfield filter developed by Lazar Greenfield that had lower complication levels associated with the filter.
Maps Inferior vena cava filter
Medical use
While the ability to retrieve filters does exist for many models, it can not be guaranteed that all filter placement cases will allow, or be indicated for retrieval. Thus, the terms and indications for permanent filter placement are used to decide when to use permanent and temporary IVC filters.
Long-term risk factors should also be considered, to include life expectancy of more than six months after insertion, and the patient's ability to adhere to anticoagulant therapy. The decision to use temporary vs permanent filters is essentially related to the expected duration of time that protection is required to prevent pulmonary emboli from moving to the heart and lungs. One of the guidelines is described below:
- Contraindications to anticoagulants; for example a patient with DVT or PE who has other conditions that put them at risk of bleeding, such as recent bleeding into the brain, or patients who will undergo major surgery
- Short-term risks PE/Contraindications short-term anticoagulants: Usually the benefits of filters that can be taken
- Uncertain risk of PE and/or lack of control for anticoagulation: Usually produces permanent filters for long-term management
- Long-term repeat PE/PE risk/Repeat DVT: permanent filter
Category indication
While much research has been done on the efficacy of the Vena Cava filter, there is still no major research done on the actual placement and removal of filters regarding standard guidelines. That is why the Society of Interventional Radiology creates a multidisciplinary panel that develops the following guidelines to see if a person is eligible for implantation:
Absolute indication
These are patients who should consider IVC filter placement, as they are at risk of developing pulmonary embolism.
- VTE Proven: Venous thromboembolism and contraindications or complications due to anticoagulant therapy
- Recurrent VTE: Although anticoagulation therapy is sufficient
Relative indication
This may be a category; usually it represents patients who could benefit from an IVC filter, but it might be fine without one.
- Proven VTE: High risk of contraindications or complications arising during anticoagulant therapy
- Large, free-floating proximal DVT
- Poor Compliance: The INR rate is unstable, not taking the drug as directed
- Thrombolysis: Iliocaval DVT, which is an embolism in the Illiac region
Prophylactic indication
This is usually a very controversial reason to do IVC filters, and most radiologists and physicians generally would not recommend IVC filters if other options are available instead.
- No VTE: An unlikely anticoagulation therapy (high risk of bleeding)
- VTE Transient Risk: Trauma, surgical procedure or medical condition
Other indications
- Patient Bariatrics: Ongoing surgery to control weight, only if BMI is greater than 55, previous history of DVT/PE, hypercoagulation state, chronic venous insufficiency, truncal obesity or contraindications to anticoagulant therapy.
Indication to remove IVC filter
No data published at this time confirms the benefits of IVC deletion. Therefore, the Society of Interventional Radiology creates a multidisciplinary panel that develops the following guidelines to see if a person is eligible for removal:
- No permanent filter required: Temporarily delete
- Significant low PE risk: Continued anticoagulation works, temporarily delete
- No expected high-risk long-term PE: Continue anticoagulation therapy, temporarily remove
- Life expectancy of more than six months: Clear temporary
- Ability to retrieve filters: No complications, no tear probability, no trauma possibility; if so, temporarily delete
Anticoagulation
In those with early acute proximal DVT or acute PE who had IVC filters placed in place of anticoagulation, and who had a risk of completing bleeding, the American College of Chest Physicians suggested, by 2012, that they receive an anticoagulation standard course. While IVC filters are associated with long-term risk of DVT, they are not, alone, reason enough to maintain an extended anticoagulant.
Side effects
The main function of the vena cava filter is to prevent death from massive pulmonary embolism. Long-term clinical follow-up studies have shown that this is done in 96% of cases that have standard Greenfield stainless steel filters.
FDA Communication
In August 2010, the FDA released Initial Communication on Risks and Adverse Events associated with Long Term use of inferior vena cava filters. Over a period of about 5 years, they identified 921 occurrences. Although not the majority of cases, the figure still shows statistical significance from long-term IVC use.
Of the adverse effects of IVC filters, 328 involve device migration, 146 involved embolization after removal of device components, 70 involving IVC perforation, and 56 involved filter fracture. Many medical communities believe that a large number of these side effects are associated with the remaining cardiac filters in place longer than necessary.
Common problems related to failure, including death (4% of other cases) include:
- Device related morality
- Device migration
- Filter embolization
- Fracture filter
- Site insertion thrombosis
- Perforation of vena cava
- Repeat DVT
- PE recursed
- Thrombotic complications
- Vena cava thrombosis
Bad reaction less common
Although these side effects are uncommon (less than 10-20% of patients), many report problems arising from IVC placement and complications while in the body.
- 9% (12 of 132 patients) delayed IVC filter penetration greater than 3 mm
- Some filters are disconnected in 2% (5 of 230 patients)
- Bag filters migrate to the heart or pulmonary artery (4 patients)
Many small published articles and case study reports illustrate similar problems above. Especially:
- Fracture filter: Struts damaged to migrate to the retroperitoneum, requiring exploration. Also struts can migrate to the heart and can cause pericardial effusion and tamponade.
- Perforation to the duodenum: Produce severe diarrhea and weight loss.
- Arterial hemorrhage: Requires surgery to avoid death. Filters
- Wrong Place: Causes pericardiac tamponade requiring surgery under the cardiopulmonary bypass.
- Migration Filters to the Right Atrium: Resulting in acute myocardial infarction.
- Filters Placed in the Heart: Causes life-threatening arrhythmias and often require pacemakers to resolve conditions.
- Heart Migration: Requires surgery to remove IVC from the liver.
- Sudden Death: Caused by filters that migrate to the active region of the heart.
- Filter Migration to Chest: Requires operation.
- Perforation of strut filter into small intestine: Requires surgery to repair perforation.
Although the above case is an exception, and not the rule, most radiologists object to the insertion of prophylactic filters in patients without thromboembolic disease. For the most part, whenever possible, interventional radiologists prefer to start patients with anticoagulants rather than using IVC, even if requested or referred through a physician.
MRI
While most IVC filters are made of non-ferromagnetic materials, there are several types of weak ferromagnetic properties. Thus, IVC filters fall under the category of MRI Safe and MRI Conditional depends largely on the type of materials used during construction. Very rarely will anyone find the MRI Not Safe IVC filter, as most of the steel, and other ferromagnetic material devices have been discontinued through the FDA.
IVC filters are attached to the vena cava through the hooks on the edges. Some are compression springs, which squeeze out into the sidewall of the cava vein; However, they still have a small hook that maintains their location. These hooks help in the process of retaining and healing, as they allow the network to 'grow' around them, securing IVC in place. It is not possible, then, after 4 to 6 weeks of healing, that a MRI of 1.5 tesla, up to 3 tesla, will cause any release rate to occur in the IVC filter.
MR examination studies on animals and humans, with embedded IVC filters, have not reported complications or displacement of symptom filters.
Some animal studies have even used MR "real-time" for IVC filter placement to check rotation, sheering, and other artifacts.
As part of the 'routing' survey for MRI studies, patients with IVC filters often require verification from a doctor, or medical record, to certify that IVC is safe for MRI. Most patients with weak or insecure ferromagnetic implants will be given a card, which people keep at all times, which can help isolate if it is safe to perform MRI.
For patients who have been rejected for an MRI scan for safety reasons, doctors usually recommend a CT scan with contrast as an alternative.
Labeling and recommendations
Most IVC filters that have been tested have been labeled "MRi safe"; the remaining IVC filters that have been tested are "conditional MR." Patients who have been treated with a nonferromagnetic IVC filter may undergo MR testing at any time after filter implantation. In patients who have been treated with a weak ferromagnetic IVC filter (IVC nest sieve Gianturco [Cook], Greenfield vena cava [Boston Scientific] stainless steel filter), it is recommended that patients wait at least six weeks before undergoing MR tests (since the older device was initially may not be firmly anchored in places like other devices discussed in this context), unless there are strong clinical indications for performing MR tests sooner after implantation, and as long as there is no reason to suspect that the device is not positioned correctly or improperly installed. Most IVC filter research has generally been performed at 1.5 tesla or less, although many IVC filters have now been evaluated on 3 tesla and are considered acceptable for MR examination.
Placements
IVC filters are placed endovascularly, meaning that they are inserted through the blood vessels. Historically, IVC filters were placed surgically, but with modern filters that can be compressed into thinner catheters, access to the venous system can be obtained through the femoral vein (the large vein in the groin), the internal jugular vein (large veins) in the neck) or arm vein with one design. The choice of route depends primarily on the number and location of blood clots in the venous system. To place the filter, the catheter is guided into IVC using a fluoroscopic guide, then the filter is pushed through the catheter and distributed to the desired location, usually just below the intersection of IVC and the lowest renal vein.
A previous cross-sectional imaging review or venogram of IVC was performed before spreading the filter to assess possible variations of anatomy, thrombus in IVC, or stenosis area, and to estimate IVC diameter. Rarely, ultrasound-guided placement is preferred in the setting of contrast allergies, renal insufficiency, and when patient immobility is desired. IVC sizes can influence which filters are used, as some (such as Bird's Nest) are approved to accommodate larger cavae. There are situations where the filter is placed over the renal vein (eg pregnant patient or woman of childbearing age, renal or gonadal vein thrombosis, etc.). Also, if there is a duplication of IVC, the filter is placed on top of the meeting of two IVCs or the filter can be placed inside each IVC.
Retrieval
The concept of removable IVC filters was first thought of in 1967. However, it was not until 2003 and 2004 that the United States Food and Drug Administration drafted regulations and requirements for making a decent device to be taken from the vena cava and still, even when the FDA approved the model and design, it was not until 2005 that the Society of Interventional Radiology (SIR) held a multidisciplinary conference to address the clinical application of non-permanent cava vein filters.
The retrievable filters are equipped with the device (varies from model to model) allowing them to be easily snared and pulled back into the catheter and removed from the body, often through the jugular vein. Prior to 2004, filters that had been in IVC for less than three weeks were considered suitable for retrieval efforts, since longer-installed filters may have been overgrown by cells from IVC walls and there was an increased risk of IVC injury. if the filter is dislodged. Newer designs, and developments in techniques mean that some filters can now be left out for long periods and withdrawals after one year are now being reported. These include ALN filters, Bard G2 and G2x, Option, Tulip and Celect.
It is important to note that clinical examination prior to filter removal is critical in understanding the risks and pathophysiological effects that eliminate the filter in patients. Doctors and medical professionals should consider several key factors (see Indications for removing IVC filters).
References
Literature quoted
- Athanasoulis, Christopher A, MD. "Complications of Vena Cava Filters" (PDF) . Journal of Radiology . 3. 188 (3): 614-615 . Retrieved 2012-10-11 .
External links
- IVC filter - emedicine.com
- IVC Filter - Medical College of Wisconsin
- IVC Filters - GPnotebook.co.uk
- Lazar Greenfield's history and its filters - Discovery & amp; Technology
- IVC lawsuit
Source of the article : Wikipedia
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