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At least 19 recordsLinked to original sources
PubMed2006

Retrieval analysis of clinical explanted vena cava filters.

Vena cava filters are the most commonly used mechanical devices to prevent pulmonary embolism. A retrievable permanent filter has been available since 1999. That has allowed the direct study of thrombi captured in humans and the punctual interaction of blood and device at long and short term. Through traditional histologic methods, captured thrombi and the tissues formed around the filter were observed. An innovative environmental scanning electron microscopy technique allowed detection of micro- and nanosized foreign bodies inside thrombi and tissues, and chemical analysis could be carried out by means of energy dispersive spectroscopy. All specimens contained different quantities of foreign debris ranging from few tens of microns to 50 nanometers; their chemistry was not homogeneous when patients were compared, and also differed considerably within the same filter. The constant presence of debris deeply embedded in all thrombi observed may mean that they are the cause that triggered the formation of those thrombi as a result of the interaction between foreign bodies and blood components.

Foreign Bodies↗
PubMed1995

[Recurrent thromboses in a 32-year-old pregnant patient with permanent vena cava filter].

Vena cava-filters are implanted where there is a risk of pulmonary embolisation as cases of thrombosis. Permanent vena cava-filters can induce various complications during the remainder of the patient's life. A case of a 32-year-old woman who became pregnant seven years after the implantation of a Kimray-Greenfield-Filter and gave birth to a healthy child is presented. During pregnancy and after the birth of a healthy child she suffered from two new thrombotic events. After the delivery, a complete thrombosis of the vena cava inferior, both venae iliacae communes and the right vena renalis were shown by computer-tomography and phlebography. Inspite of these longterm complications, pregnancy is not contraindicated after implantation of a permanent vena cava-filter.

Adult↗
PubMed2006

Numerical analysis of the hemodynamics and embolus capture of a greenfield vena cava filter.

BACKGROUND: Vena Cava filters are used to prevent pulmonary embolism in patients with deep vein thrombosis who are unresponsive to anticoagulation therapy. Various filter designs exist in the market with different characteristics distinguishing them. An understanding of the characteristics of these filters is desirable in order to develop better designs. METHODS: A computational fluid dynamical study of the flow over an unoccluded stainless steel Greenfield Vena Cava filter (Boston Scientific, Watertown, MA) to determine its properties has been performed. Simulation of flow over a filter placed axisymmetrically in a rounded inferior vena cava has been performed at a Reynolds numbers of 1000 and the consequences of the flow (by studying parameters like shear stress and stagnation zones) have been discussed. Furthermore, a new finite element based numerical method has been developed that allows the study of capturing properties of Inferior Vena Cava filters. The key idea is the introduction of a thin-wire-model (TWM) that enables a drastic reduction in the computational cost while still maintaining control on the physics of the problem. This numerical technique has been applied to evaluate the embolus capture characteristic of a Greenfield filter. RESULTS: The flow around the unoccluded filter is found to be steady and laminar at the conditions studied. A recirculation/stagnation zone develops immediately downstream of the filter head. This zone is significantly larger when the central hole is occluded. The shear stress and stagnation zone properties for such a flow over a Greenfield filter are compared with existing literature (in vitro studies). A graph showing the regions wherein clots escape or get captured has been determined by a means of numerical simulations. The data has further been analyzed to determine the probability of clot capture as function of the clot size. CONCLUSIONS: The stagnation zone formed behind the head of the Greenfield filter is found to be smaller in size when compared to that of the same filter with the central hole occluded. A map of the shear stress distribution shows a small region having the potential for thrombogenesis. The non-Newtonian properties of blood are not seen to cause much variation in the flow field when compared to the Newtonian model. However variation in the cava size leads to a significant change in the shear stresses. This study also establishes a novel method wherein computational means are used to determine the efficacy of clot capturing of filters. These techniques can further be used to compare the different characteristics among filters.

Blood Flow Velocity↗
PubMedDate not supplied

Venous interruption as prophylaxis of pulmonary embolism: vena cava filters.

Interruption of vena cava for prevention of pulmonary embolism (PE) was achieved in the past with surgical ligation or placement of clips outside the infrarenal vena cava. At present, this procedure is performed with percutaneous insertion of vena cava filters. Vena cava filters can be permanent or temporary, catheter-retrievable. Main indications for placement of a vena cava filter are: contraindication for anticoagulant therapy in patients with severe PE in whom a further embolic episode would be fatal or patients with PE (or its recurrence) undergoing adequate anticoagulant therapy. Temporary filters are reserved to patients where the risk of PE is limited in time as in posttraumatic, post-partum or postoperative thromboembolism. The incidence of recurrence after placement of a vena cava filter varies between 0.5 and 7%. Procedure-associated complications are usually mild. However, severe complications as filter migration into the pulmonary artery or vena cava perforation were described. Our experience concerns the insertion of 61 vena cava filters (47 permanent and 14 temporary). Indications were as follows: iliofemoral thrombosis at embolic risk (37 cases), contraindication for anticoagulant therapy in the presence of deep vein thrombosis with embolic risk (7 cases), protection during fibrinolytic therapy (3 cases), PE during anticoagulant therapy (5 cases) complications of anticoagulant therapy which required discontinuation (5 cases), prophylaxis in view of surgery at high risk for PE (2 cases), protection for surgical venous thrombectomy (2 cases). Mortality was nil. Clinically evident PE was not observed in any patient in whom vena cava filter was inserted. Complications were mild and asymptomatic. Vena cava filters represent an effective prevention of PE together with medical and surgical treatment. At present, problems of this procedure are not technical but rather concern correct indications. Interruption of vena cava is effective if planned within a global strategy for prevention of thromboembolism.

Adolescent↗
PubMedDate not supplied

Optional vena cava filters: preliminary experience with a new vena cava filter.

PURPOSE: To prevent pulmonary embolism, some clinical situations only need a vena cava filter for several days, without the inconveniences of temporary vena cava filters in the short-medium term and without the drawbacks of permanent ones in the long term. We report our initial experience with a new definitive vena cava filter, easy to retrieve when it becomes unnecessary. MATERIAL AND METHODS: From the beginning of January 1999 to December 2001, 18 ALN vena cava filters were deployed. The approach used was transbrachial in ten patients, transjugular in seven, and transfemoral in the others. The indications were pelvic trauma in eleven patients, hip replacement in three; four filters were "prophylactically" placed before surgery in patients at high risk of thromboembolic disease (three with ileal or femoral or ileo-femoral thrombosis, and one without clinically manifest thromboembolic disease). Optional vena cava filters were evaluated for malpositioning, caval perforation, filter migration, acute caval thrombosis or access site thrombosis. Seven optional vena cava filters were retrieved. CT was performed before retrieving the vena cava filters to document the absence of thrombi inside the filters. The transjugular ap-proach was used to retrieve the filters. RESULTS: Technical success was achieved in all patients. No complications were encountered during the procedure; no migration or rupture of the filters was detected during the follow-up. No thrombosis of the vena cava or at the insertion site was encountered. The median retrieval time for the filters was 12': only the transfemoral filters required 15' of fluoroscopy. The median permanence was 63 days. No thrombi were found inside the filters. DISCUSSION: A definitive vena cava filter, easy to retrieve when it becomes unnecessary, is the ideal device in many clinical conditions: young subjects with pelvic fractures orthopaedic and gynaecologic interventions.

Adult↗
PubMed1995

Vena cava filter devices.

Vena cava filters are effective in preventing pulmonary embolism (PE) in patients with deep vein thrombosis or PE who either have contraindications to anticoagulation or have sustained a PE despite adequate anticoagulation. Although vena cava filters are not without complications, clinically significant morbidity and mortality are low. The use of vena cava filters as primary prophylaxis or therapy for deep vein thrombosis and PE should await the results of controlled trials.

Anticoagulants↗
PubMed2001

Right heart catheterization in the presence of an inferior vena cava filter.

Inferior vena cava filters are being inserted with increasing frequency. When such patients later require right heart catheterization, brachial or jugular vein access is usually attempted. We describe our experience in 10 consecutive patients using the standard femoral approach, first assessing filter patency and then carefully crossing the filter using a straight guidewire. The right heart chambers were successfully accessed in every case. There were no complications, and in no case did the filter migrate or become dislodged. This technique may prove useful when right heart catheterization is indicated in a patient who has a Greenfield inferior vena cava filter.

Aged↗
PubMed1998

A large embolus trapped by an inferior vena cava filter: a case report supporting inferior vena cava filter insertion.

We describe a patient with a deep vein thrombosis causing multiple pulmonary emboli. After inferior vena cava filter insertion, a large embolus was trapped by the filter. Anticoagulation following filter insertion decreased the pulmonary artery pressure, and there was no recurrence of pulmonary embolization. Thus, in the presence of large, multiple thrombi in the proximal veins, inferior vena cava filter had better be inserted before thrombolytic treatment to prevent a lethal pulmonary embolism, and anticoagulant therapy is important after filter insertion.

Humans↗
PubMed2003

Inferior vena cava filter placement: preinsertion inferior vena cava imaging.

Imaging of the vena vava prior to the insertion of an inferior vena vava (IVC) filter is mandatory to assess IVC diameter and patency, delineate anatomy and venous anomalies, and to direct filter placement for appropriate deployment and avoidance of complications. The standard imaging technique is vena cavography, although alternative methods to evaluate the inferior vena cava include carbon dioxide venography, transabdominal duplex ultrasound, and intravascular ultrasound. This manuscript will review the anatomical features, technique, and complications of pre-insertion inferior vena cava imaging and discuss alternative methods to evaluate the inferior vena cave prior to filter insertion.

Angiography, Digital Subtraction↗
PubMed1987

[Initial experiences with angiodynography (color-coded duplex sonography) in the follow-up of vena cava filters].

In vena cava filter thrombosis, plain films and real-time B-mode ultrasound are not reliably diagnostic. Angiodynography (colour-coded duplex ultrasound) was performed in 15 patients as an alternative to invasive methods. Despite of the relatively low depth of the used 5 MHz transducer, in 14 patients blood flow in the vena cava could be identified successfully. A nearly total occlusion of filter could be demonstrated in one case; in another patient partial thrombosis was not detected. Flow alterations around the filter were seen in the majority of cases. First experiences with the method were satisfying with regard to the particular problem.

Color↗
PubMed2003

Overview of current inferior vena cava filters.

Inferior vena cava (IVC) filter technology has expanded dramatically over the past decade. Improvements in catheter and filter technology have allowed for the safe and rapid insertion of IVC filters from multiple venous access sites, using increasingly lower-profile percutaneous delivery systems. While the currently available filters have slightly different designs and insertion techniques, all function in a similar fashion to prevent venous thromboembolic propagation through the inferior vena cava. This article describes the construction and deployment mechanisms of the various filters that are currently on the market.

Equipment Design↗
PubMed2003

Complications of inferior vena cava filters.

Inferior vena cava (IVC) filters offer a safe and effective means of preventing pulmonary embolus and have reduced complications when compared to earlier techniques of caval interruption. However, despite continued improvement in filters and insertion methods, complications still occur. Pneumothorax, hemorrhage, and vessel injury may result while obtaining vascular access. Filter misplacement, excessive tilt, and vascular injury have been reported with insertion, but preinsertion cavography is helpful in preventing these insertion-related complications. Attention to detail, proper use of guidewires, and preinsertion imaging are vital in preventing insertion-related complications as well. Long-term complications occur in a minority of patients and include recurrent pulmonary embolus, caval occlusion, and filter migration. Overall, the benefits of preventing pulmonary embolism far exceed the risks related to filter placement in properly selected patients.

Humans↗
PubMed2005

Long lives, short indications. The case for removable inferior cava filters.

Vena cava filters have been in use for decades to prevent pulmonary embolization from deep venous thrombosis. These filters have been shown to be effective, with fairly low rates of filter migration, fracture and thrombosis. However considering that filters remain in situ for the life of the patient and that studies do not show increased longevity in patients with filters, any complications from filters are significant concerns. In addition, often patients require filters for only temporary indications, e.g. contraindication for anticoagulation because of impending procedures, or for only a transient risk period, as in trauma or pregnant patients. In these cases, removable filters may be more appealing. This review will examine the different types of removable filters and the indications in which removable filters may have an advantage over permanent filters.

Disposable Equipment↗
PubMed2005

Removal of the OptEase retrievable vena cava filter is not feasible after extended time periods because of filter protrusion through the vena cava.

BACKGROUND: Therapeutic and prophylactic vena cava filters (VCFs) are used to prevent pulmonary embolism. Concerns exist over placing a permanent filter in a young trauma patient. Recently, retrievable VCFs have become available. One such filter is the OptEase, which has a recommended time of removal of up to 23 days after insertion. Data supporting this recommendation are sparse. Many trauma patients will need filters for more than 2 weeks, and there are no data evaluating the safety of removal after extended time periods. The purpose of this study was to determine the safety, feasibility, and reaction of the vena cava when removing the OptEase retrievable VCF at different time intervals. METHODS: Twenty Yorkshire cross pigs (80-113 kg) underwent general anesthesia with tiletamine and zolazepam. Filters were placed in the infrarenal vena cava (VC) through the femoral vein under fluoroscopic guidance. Animals were then divided into four groups. In group 1, filters were removed at 14 days; in group 2, at 30 days; in group 3, at 60 days; and in group 4, at 90 days. Removal was attempted using a snare-and-sheath technique through the femoral vein. Animals with successful filter removal were allowed to recover; then, the animals underwent autopsy (gross and microscopic VC examination) 2 months later. Animals with unsuccessful filter removal underwent autopsy immediately after attempted removal. Venacavograms were taken at filter insertion, at removal, and before autopsy to evaluate any VC abnormalities. RESULTS: Successful removal of the filter in all five pigs (100%) was reliably performed only in the 14-day group. In this group, the initial VC transverse diameter was 19.4 +/- 0.8 mm and was significantly reduced to 9.8 +/- 1.1 mm (p < 0.05) immediately after removal. Sixty days later, before autopsy, VC diameter had increased to 15.3 +/- 1.9 mm, which was significantly larger than at removal (p < 0.05) but not different from the initial value. In the 30-day group, removal was successful in only one of five animals. Although removal was successful in the one pig, autopsy at 2 months postremoval revealed total occlusion of the VC. Filters could not be removed from 60- and 90-day groups. At autopsy, the VCF struts were embedded or protruded through the VC wall. Microscopic examination of the VC revealed significant scarring underneath and between the struts. CONCLUSION: Removal of the retrievable OptEase VCF may be successfully performed up to 14 days after insertion. Strut protrusion through the VC wall prohibited successful and safe removal at extended time intervals.

Animals↗
PubMed1995

Physico-chemical observations on a failed Greenfield vena cava filter.

A Greenfield vena cava filter for the prevention of thromboembolism failed in vivo due to the displacement of 2 of the 6 legs and their subsequent break. The explanted stainless steel filter was analyzed with an electron microscope and energy dispersion system in order to assess the reason for the break. Fatigue and corrosion of the metal were responsible for the failure.

Corrosion↗
PubMed1991

Venography and vena cava filters.

Placement of inferior vena cava filters has become a standard part of a radiology practice. However, the number of filters on the market has increased dramatically. This paper attempts to discuss the various ramifications of the filters available. However, without a long term standardized study, we will not have the necessary information to adequately judge the effectiveness of these filters.

Angiography, Digital Subtraction↗
PubMed1982

Comparative in vitro evaluation of the nitinol inferior vena cava filter.

An inferior vena cava filter made from nitinol, a thermal shape memory alloy, was evaluated. A series of in vitro experiments was designed to assess its shape recovery, orientation, and positioning after delivery and its embolus-capturing efficiency. For comparison, the Mobin-Uddin and Kimray-Greenfield filters were also tested. The results indicate that the nitinol filter is easily and accurately delivered and is superior to the other filters in its ability to capture emboli. In addition, it showed no tendency to migrate or to elevate the upstream hydrostatic pressures significantly.

Alloys↗
PubMed2004

Hemodynamic effects of clot entrapment in the TrapEase inferior vena cava filter.

PURPOSE: The TrapEase vena cava filter has a symmetric design. Emboli can be trapped in the outlet conical section (superior cone) or between the filter and vessel wall at the inlet end (inferior cone). The purpose of this in vitro study is to investigate the hemodynamic effects of clot entrapment by the TrapEase filter and to examine the possibility of flow-induced filter thrombosis. MATERIALS AND METHODS: Velocity and wall shear stress maps were determined for steady flow with use of the photochromic flow visualization technique. Experiments were done for a filter without clot and for three other cases: an asymmetric clot in the inferior zone, a symmetric clot in the superior zone, and a filter with both zones partially occluded. Each simulated clot was 1500 mm(3) and the vessel diameter was 2 cm. RESULTS: The unoccluded filter did not significantly affect the flow field. However, for a partially occluded filter, flow stagnation/recirculation and turbulence developed downstream from the clot. The greatest effect was noted when the clot was against the vessel wall in the inferior trapping region. CONCLUSIONS: The tendency for clots to be trapped between the filter and the vessel wall in the inferior (inlet) region may play an important role in the performance of the TrapEase filter. A clot in this configuration will generate a large region of flow stagnation/recirculation that is considered to be prothrombotic. In addition, a significant amount of the filter wire will be embedded in this region, which may also promote thrombosis.

Blood Flow Velocity↗