Hematologists are often asked to treat patients with venous thromboembolic disease. Although anticoagulation remains the primary therapy for venous thromboembolism, vena caval filters are an important alternative when anticoagulants are contraindicated. To assess the evidence supporting the utility of these devices, a comprehensive review of the English language literature was performed. Except for one randomized trial, the vena caval filter literature consists of case series or consecutive case series. The mean duration of follow-up for each of the 5 filter types varies from 6 to 18 months. All are about equally effective in the prevention of pulmonary embolism (2.6%-3.8%). Deep venous thrombosis (6%-32%) and inferior vena cava thrombosis (3.6%-11.2%) after filter placement vary widely among different filter types primarily because of differences in outcome assessment. Thrombosis at the insertion site is a common complication of filter placement (23%-36%). In view of the absence of randomized comparisons, no filter can be designated as superior in safety or efficacy. Vena caval filters represent a potentially important but poorly evaluated therapeutic modality in the prevention of pulmonary emboli. Randomized trials are necessary to establish the appropriate place for vena caval filters in the treatment of venous thromboembolic disease.

Venous thromboembolic disease is a significant cause of morbidity and mortality in the United States. Pulmonary embolism (PE), the most deadly form of venous thromboembolic disease, is diagnosed in 355 000 patients and results in as many as 240 000 deaths per year.1 In most clinical situations, anticoagulation is the preferred form of therapy. Although generally associated with a small (less than 5% per year) risk of major hemorrhage in the average patient, anticoagulation is more risky in selected patient populations (patients with thrombocytopenia, central nervous system [CNS] metastases, active gastrointestinal bleeding, and so forth).2 In these instances, vena caval filters have been considered an effective alternative form of therapy for venous thromboembolic disease. As hematologists, we are often asked to make decisions on the placement of vena caval filters. Unfortunately, the literature supporting the utility of these devices is scattered among a diverse collection of journals not typically read by many practitioners. The purpose of this comprehensive review is to summarize and critique the published data on vena caval filters and thus facilitate informed clinical decision-making by hematologists.

A comprehensive search of the Medline database was performed using the keywords Greenfield filter, bird's nest filter, titanium Greenfield filter, Simon nitinol filter, Vena-Tech filter, temporary vena caval filter, vena caval filter, thrombosis, deep venous thrombosis, pulmonary embolism, anticoagulation, and bleeding. Additional articles were identified by a careful review of reference lists. Study design was reviewed and data from each article were abstracted and entered into a database for analysis. Complication rates were calculated by dividing the number of patients suffering a particular complication by the population examined for that event. Patients listed as lost to follow-up or dead were not included in the denominator when calculating complication rates. None of the studies reviewed fulfilled the recently published guidelines for vena caval filter placement and patient follow-up.3 

Vena caval filter studies: stainless steel Greenfield filter

Five different vena caval filters are available in the United States: the over-the-wire stainless steel alternating-hook Greenfield filter, the titanium Greenfield filter, the bird's nest filter, the Simon nitinol filter, and the Vena Tech filter (Figure1). The over-the-wire stainless steel alternating hook Greenfield filter has recently replaced the original stainless steel Greenfield filter, because its design modifications allow easier percutaneous placement.4 Both consist of a cone-shaped array of 6 stainless steel wires, which end in hooks that secure the device in the inferior vena cava (IVC).

Fig. 1.

Diagram of the permanent vena caval filter models.

(A) The stainless steel Greenfield filter. (B) The modified-hook titanium Greenfield filter. (C) The bird's nest filter (D) The Simon nitinol filter. (E) The Vena Tech filter.

Fig. 1.

Diagram of the permanent vena caval filter models.

(A) The stainless steel Greenfield filter. (B) The modified-hook titanium Greenfield filter. (C) The bird's nest filter (D) The Simon nitinol filter. (E) The Vena Tech filter.

Close modal

Because the newer Greenfield filter has been evaluated in few patients, this review will focus on the original stainless steel Greenfield filter, which has been investigated in 40 different case series involving 3184 patients (Table1).5-36 All the studies are case series and most are retrospective. The most common reasons for filter placement are a contraindication to anticoagulation, a complication from anticoagulation, or a failure of anticoagulation. In some series, a substantial number received filters for prophylaxis. Study populations vary from 6 to 642 participants. Serious procedural complications (eg, pneumothorax, 2 cases; cerebrovascular accident, 1 case; and death, 3 cases) are rare. The duration and intensity of the follow-up after filter placement varies considerably among studies (Table 1). In most cases, follow-up information is based on chart reviews, telephone questionnaires, or clinic visits (combined, 86% of study population). A minority of patients had radiologic surveillance (ultrasonography, 22%; computed tomography [CT] scans, 1.5%; and inferior venacavograms, 8.4%), a weakness that must be considered when reviewing event rates.

Table 1.

Compilation of vena caval filter study data

Filter type Study no. Patient no. F/U duration (in mo) PE DVT IVCT Postphlebitic syndrome
Stainless steel Greenfield  40  3184  18 (1-60) 66/2561 (2.6%)  96/1634 (5.9%)  73/2033 (3.6%) 254/1353 (19%)  
    (range 0-9%) 
    fatal 22 (0.9%)  (range 0-18%)  (range 0-18%)  (range 0-47%)  
Titanium Greenfield  10  511 5.8 (0-81)  13/422 (3.1%)  5/22 (22.7%) 15/230 (6.5%)  34/236 (14.4%)  
    (range 0-3.8%)  
    fatal 7 (1.7%)  (range 0-36%) (range 1-31%)  (range 9-20%)  
Bird's nest  16  1426 14.2 (0-60)  32/1111 (2.9%)  27/448 (6%) 36/940 (3.9%)  37/267 (14%)  
    (range 0-4.2%)  
    fatal 10 (0.9%)  (range 0-20%) (range 0-15%)  (range 4-41%)  
Simon nitinol  8  319 16.9 (0-62)  10/265 (3.8%)  11/123 (8.9%) 17/220 (7.7%)  16/124 (12.9%)  
    (range 0-5.3%)  
    fatal 5 (1.9%)  (range 8-11%) (range 4-18%)  (range 6-44%)  
Vena Tech  15  1050 12 (0-81)  33/963 (3.4%)  8/25 (32%) 83/741 (11.2%)  95/232 (41%)  
    (range 0-8%)  
    fatal 3 (0.3%)  (range 32%)  (range 0-28%)  (range 24-59%) 
Filter type Study no. Patient no. F/U duration (in mo) PE DVT IVCT Postphlebitic syndrome
Stainless steel Greenfield  40  3184  18 (1-60) 66/2561 (2.6%)  96/1634 (5.9%)  73/2033 (3.6%) 254/1353 (19%)  
    (range 0-9%) 
    fatal 22 (0.9%)  (range 0-18%)  (range 0-18%)  (range 0-47%)  
Titanium Greenfield  10  511 5.8 (0-81)  13/422 (3.1%)  5/22 (22.7%) 15/230 (6.5%)  34/236 (14.4%)  
    (range 0-3.8%)  
    fatal 7 (1.7%)  (range 0-36%) (range 1-31%)  (range 9-20%)  
Bird's nest  16  1426 14.2 (0-60)  32/1111 (2.9%)  27/448 (6%) 36/940 (3.9%)  37/267 (14%)  
    (range 0-4.2%)  
    fatal 10 (0.9%)  (range 0-20%) (range 0-15%)  (range 4-41%)  
Simon nitinol  8  319 16.9 (0-62)  10/265 (3.8%)  11/123 (8.9%) 17/220 (7.7%)  16/124 (12.9%)  
    (range 0-5.3%)  
    fatal 5 (1.9%)  (range 8-11%) (range 4-18%)  (range 6-44%)  
Vena Tech  15  1050 12 (0-81)  33/963 (3.4%)  8/25 (32%) 83/741 (11.2%)  95/232 (41%)  
    (range 0-8%)  
    fatal 3 (0.3%)  (range 32%)  (range 0-28%)  (range 24-59%) 

Abbreviations: F/U indicates follow-up; PE, pulmonary embolism; DVT, deep venous thrombosis; IVCT, inferior vena caval thrombosis.

Note: The denominators of the various complications only include patients who were evaluated (ie, patients lost to follow-up or dead are not included. Only a portion of the studies evaluated patients for all these events).

The primary purpose of implanting a vena caval filter is to prevent PE. Only 66 patients suffered a PE following Greenfield filter insertion; 22 were fatal. These numbers compare favorably with anticoagulation in the management of venous thromboembolic disease.37-43 Deep venous thrombosis (DVT) developed in 6%. Only a portion of the study population was assessed for this event. Therefore, the actual DVT frequency after Greenfield filter placement is probably somewhat higher.

Insertion site thrombosis (IST) is a venous thrombus that develops at the vascular access sites where filters are initially inserted. IST was identified in 87 patients. However, as with other complications of filter placement, the frequency varies with the surveillance intensity. Studies with routine ultrasound screening identified IST in 23% of participants (Table 2). Because most of these thrombi were asymptomatic, their clinical significance is unknown. Long-term follow-up studies of patients with asymptomatic IST are warranted.

Table 2.

Insertion site thrombosis rates for vena caval filters

Filter type IST—No surveillance IST—Routine surveillance
Stainless steel Greenfield  87/898 (9.6%)  50/217 (23%) 
 Range 1-47%  Range 14-41%  
Titanium Greenfield 35/267 (13.1%)  23/82 (28%)  
 Range 2-50% Range 25-50%  
Bird's nest  31/417 (7.4%) 23/101 (23%)  
 Range 0-33%  Range 21-33%  
Simon nitinol  22/191 (11.5%)  11/36 (31%)  
 Range 0-64% Range 16-64%  
Vena Tech  36/215 (16.7%)  16/44 (36%) 
 Range 8-44%  Range 34-44% 
Filter type IST—No surveillance IST—Routine surveillance
Stainless steel Greenfield  87/898 (9.6%)  50/217 (23%) 
 Range 1-47%  Range 14-41%  
Titanium Greenfield 35/267 (13.1%)  23/82 (28%)  
 Range 2-50% Range 25-50%  
Bird's nest  31/417 (7.4%) 23/101 (23%)  
 Range 0-33%  Range 21-33%  
Simon nitinol  22/191 (11.5%)  11/36 (31%)  
 Range 0-64% Range 16-64%  
Vena Tech  36/215 (16.7%)  16/44 (36%) 
 Range 8-44%  Range 34-44% 

Abbreviation: IST indicates insertion site thrombosis.

Although a less common event with current methods of venous interruption, inferior vena cava thrombosis (IVCT) remains a complication of Greenfield filter placement. Anecdotal cases of massive lower extremity swelling and phlegmasia cerulea dolens have been seen in conjunction with IVCT, occasionally with lethal consequences.44-46 More commonly, by impairing lower extremity venous drainage, IVCT predisposes patients to recurrent DVT and the postphlebitic syndrome.47,48 The venous collateral vessels that develop after IVCT also can become alternative routes for PE.49,50 In the Greenfield filter series, IVCT appears to be a rare event. Only 73 (3.6%) patients developed it during follow-up. Incomplete follow-up and the use of insensitive diagnostic techniques, however, suggest that this event may be underdiagnosed.47 51 

Penetration of the IVC wall by filter prongs, migration, tilting, and fracture of filters are infrequent and predominantly asymptomatic events noted during the follow-up of patients after vena caval filter placement. Penetration of the IVC wall by the legs of a Greenfield filter has been associated with perforation of the small bowel, ureter, and aorta as well as retroperitoneal hematomas and small-bowel obstruction.52-57 Fortunately, symptomatic penetration is a rare event. Only 63 of 1448 patients (4.4%) with stainless steel Greenfield filters had evidence of IVC penetration and only 6 (0.4%) were symptomatic.

Another highly publicized complication is filter migration into the heart or pulmonary arteries.58 59 Migration usually is defined as caudal or cranial movement in excess of 1 cm. Only 5.3% of patients (70 of 1329) were documented to have filter migration and clinically significant sequelae occurred in only 5 patients (0.4%). No cases of migration into the heart or pulmonary arteries were described.

Occasionally, Greenfield filters tilt after placement in the IVC. In the studies reviewed, 3 of 623 filters (5.3%) were found to be tilted more than 10° from the central axis of the IVC. Theoretically, eccentric placement might be anticipated to impair performance, although no PEs have been linked to this finding.16 60-62Five of 385 filters surveyed were noted to have fractured during follow-up. No adverse events were noted. Therefore, its significance remains unknown. Oral anticoagulants were used in 37% of patients during follow-up.

The potential advantage of vena caval filters is that by virtue of their permanence, they can provide life-long protection from PE. Unfortunately, if caval thrombosis develops, this virtue also can become a liability. One potential long-term consequence of caval thrombosis or DVT is the development of the postphlebitic syndrome. Symptoms of the postphlebitic syndrome include leg swelling and ulceration. Overall, 254 patients (19%) developed postphlebitic symptoms. Given the short follow-up duration in most studies and the slow progression of postphlebitic syndrome, it is likely that this frequency is an underestimate.63 64 However, filter recipients typically have multiple reasons for developing this syndrome. Therefore, only a prospective randomized clinical trial of vena caval filters and anticoagulation with long-term follow-up will be able to determine if filters predispose patients to development of this syndrome.

Titanium Greenfield filter

To address concerns about venous trauma and thrombosis attributed to the stainless steel filter's large insertion catheter (29F outer diameter), Greenfield and colleagues redesigned his filter using titanium to allow the use of a smaller introducer system (14F outer diameter).65 The initial model was troubled by a tendency to migrate, tilt, and perforate the inferior vena cava.66 67 Modifications of the filter limb and hook corrected these problems and this filter, the modified-hook titanium Greenfield filter, was introduced in 1991 (Figure 1). Only studies of this version of the titanium Greenfield filter are reviewed.

Ten case series were retrieved from the literature on the modified-hook titanium Greenfield filter involving 511 patients (Table1).44,68-76 Insertion complications are unusual except for filter limb asymmetry, which was noted in 7.6% of patients (27 of 354). Filter limb asymmetry, when the distribution of filter limbs within the IVC lumen is asymmetrical, might be anticipated to impair filtration efficiency; however, no clinical sequelae have been reported.77-79 

Follow-up information was available on 75% (450 of 599) of participants. More intense radiologic surveillance (abdominal radiograph, 258 of 599, 43%; ultrasound, 247 of 601, 41%; CT scans, 40 of 599, 7%) was used compared with the stainless steel Greenfield filter, but the mean follow-up duration was only 5.8 months (range, 0-81 months).

The modified-hook titanium Greenfield filter appears to be as effective as the stainless steel model in preventing PE. Data on the frequency of DVT after filter placement were not routinely collected, so comparisons are difficult for this complication. Theoretically, the lower profile of the titanium Greenfield filter should result in fewer insertion site thrombi; however, the frequency (13.1%, 35 of 267) was similar to that seen with the bulkier stainless steel filter. In studies with routine IST surveillance, 28% of patients developed thrombosis (Table 2). Thus, regardless of catheter size, IST remains a frequent complication of filter placement.

Inferior vena caval thrombosis occurred in 6.5% of patients with the modified-hook titanium Greenfield filter. Greater radiologic surveillance probably accounts for the higher frequency of IVCT compared with the stainless steel Greenfield filter. Postphlebitic syndrome developed in only 14% of the recipients of the titanium Greenfield filter recipients. This favorable outcome is likely a consequence of the shorter follow-up compared with the stainless-steel filter (5.8 versus 18 months).

Migration (33 of 258, 12.8%) and tilting (11 of 89, 12.4%) were more common among the titanium Greenfield filter series, whereas IVC penetration (10 of 258, 3.5%) occurred at a comparable rate to the stainless steel filter. Filter fracture, which was assessed in only 1 series, was not noted in any patients. All of these events were without apparent clinical consequences.

Bird's nest filter

In 1984, Roehm et al80 published the initial clinical investigation of the bird's nest filter. Unlike the conical design of the Greenfield filters, the bird's nest filter consists of 4 stainless steel wires, 0.18 mm in diameter and 25 cm in length, which are affixed to the vena caval wall by V-shaped struts bearing hook-like anchors (Figure 1). Its unique design allows it to be loaded into an 14F insertion catheter and gives it the flexibility to be placed into vena cavae up to 40 mm in diameter, the largest of any filter on the market (other filters are limited to cavae of 30 mm or less).81,82Unfortunately, the original design of the bird's nest filter had a tendency to migrate, which resulted in several deaths. Thereafter, stiffer, wider struts were used, which greatly diminished this tendency.81 

Sixteen case series of the bird's nest filter exist in the English literature involving 1426 patients (Table1).46,71,72,74,76,81 83-92 In common with all the filter literature, a mixture of prophylactic and therapeutic indications was cited as the reason for filter insertion. Study populations varied from 5 to 568 participants. Significant procedural complications were rare and compare favorably with the Greenfield filter models. A weakness of the bird's nest filter studies performed to date is the intensity of patient follow-up. The majority of the patients had clinical/chart follow-up alone (1182 of 1426, 83%). Radiologic surveillance was rare (abdominal radiograph, 166 of 1426, 12%; ultrasonography, 144 of 1426, 10%; CT scan, 76 of 1426, 5%; inferior venacavogram, 27 of 1426, 1.9%). The mean duration of follow-up was 14.2 months (0-60 months).

Pulmonary emboli, DVT, and IST occurred at frequencies comparable to those with the Greenfield filter models (Tables 1 and 2). Substantial increases in the number of IST diagnosed were seen in studies using routine screening procedures. IVCT and postphlebitic syndrome developed in a minority of patients. Only 4 of 15 studies documented postphlebitic symptoms among their patients.84 87-89 

Phlegmasia cerulea dolens was reported in only 2 patients after filter insertion. Filter migration (11 of 588, 1.9%) and fracture (3 of 107, 2.8%) were infrequent and asymptomatic except for migration causing the death of 1 patient. Penetration of the IVC wall was only noted in a few studies. It happened frequently (52 of 137, 37.9%) but was asymptomatic.

Simon nitinol filter

The Simon nitinol vena caval filter is constructed of a nickel-titanium alloy that has thermal memory properties. At 4° to 10°C, the wires, which compose the filter, are folded into a straight and compact form fitting into a 9F catheter carrier. At body temperature, the wires are programmed to unfold into an umbrella filter composed of 7 “petals” and 6 hooked legs that anchor the device in the vena cava (Figure 1).

Since 1989 when the first clinical study of the Simon nitinol filter was published, it has been studied in 8 different trials comprising 319 patients (Table 1).51,72,74,76 93-96 Procedural complications are extremely rare. Difficulty releasing the filter into the IVC was noted in 1 patient (0.3%). Chart review follow-up of 99.4% (317 of 319) of the study population is available for a mean duration of 16.9 months (0-62 months). Ten percent (32 of 319) of patients had follow-up clinic visits; 31% (99 of 319) had at least 1 abdominal radiograph in follow-up. Ultrasonography was performed in 41% (132 of 319) of patients, whereas magnetic resonance imaging (MRI) and CT scans were done in 12.2% (39 of 319) and 18.2% (58 of 319), respectively. Ventilation-perfusion scans (1 of 319, 0.3%), inferior venacavograms (8 of 319, 2.5%), and intravascular ultrasound (5 of 319, 1.6%) were rarely performed.

Pulmonary emboli, both fatal (1.9%) and nonfatal (10 of 265, 3.8%), were uncommon. DVT and IVCT occurred in 8.9% (11 of 123) and 11.5% (22 of 191) of patients (Tables 1 and 2). Routine surveillance for IST documented thrombosis in 31% of patients.74 76 Thrombosis of the IVC occurred in 7.7% (17 of 220) of patients. More liberal use of effective screening studies (MRI and CT scans) may be responsible for the higher rate of IVCT. Postphlebitic symptoms occurred in 12.9% (16 of 124) of the study population. Only 2 patients (0.7%) developed phlegmasia cerulea dolens after filter placement.

Penetration of the IVC wall (45 of 122, 36.9%), migration (3 of 135, 2.2%), and fracture (10 of 71, 14.1%) were recorded in only a few studies; therefore, the frequency of these complications may not be accurate. Only 1 patient with IVC penetration (0.8%) was symptomatic.94 Crossed filter legs were noted in 4 of 44 participants (9.1%) in 1 study. Although theoretically this event might be predicted to impair the filter efficiency, no clinical sequelae were noted.93 Thirty-nine percent of patients received oral anticoagulants for several months after filter insertion.

Vena Tech filter

The Vena Tech vena caval filter is constructed of Phynox, a unique nonparamagnetic alloy (cobalt 42%, chromium 21.5%, iron 8.85%, nickel 18%, molybdenum 7.5%, magnesium 2%, and a maximum of 0.15% carbon and beryllium 0.001%). Six struts are fused into a cone-shaped filter reminiscent of the Greenfield filter. Side rails attached to the filter cone anchor it to the vena caval wall (Figure 1).

Fifteen studies of the Vena Tech filter have been published involving 1050 patients (Table 1).46,48,71-73,75,76 97-104 The only common procedural complication was incomplete filter opening, which occurred in 57 of 842 participants (5.2%). In 5 patients (0.6%), a second filter had to be placed. Serious procedural complications were rare (death, myocardial infarction, and cardiac tamponade, 1 patient each). Eighty-nine percent of patients (931 of 1050) had at least telephone or chart review follow-up. Abdominal radiography was obtained in 600 (57.6%) patients; ultrasound was performed on 51% (539 of 1050). Inferior venacavograms were done in 259 patients (25%). CT scans (51 of 1050, 4.9%), ventilation-perfusion scans (46 of 1050, 4.4%), autopsies (4 of 1050, 0.4%), and venograms (2 of 1050, 0.2%) were obtained less often.

The mean follow-up duration was 12 months (range, 0-81 months). Nonfatal and fatal PE occurred at comparable rates to other filters. DVT was documented in only 1 study, which identified it in 32% of participants (8 of 25).72 IST was assessed in 5 studies in which the combined rate was 16.7% (36 of 215) (Table 2).73,75,76,97,103 Thirty-six percent of patients with routine imaging had an IST diagnosed.73 76 

Thrombosis of the IVC occurred in 11.2% of patients receiving the Vena Tech filter. Postphlebitic syndrome developed in 95 patients (41%). The more intense follow-up procedures used in the Vena Tech studies are probably responsible for these higher complication rates. Filter migration (55 of 661, 8.3%), tilt (30 of 640, 4.7%), and fractures (2 of 117, 1.7%) occurred infrequently and were asymptomatic in all participants. Anticoagulant use was frequent after filter placement, being present in 68% of patients at follow-up.

Until 1998, the only clinical data available on vena caval filters were derived almost exclusively from retrospective unrandomized case series. In 1998, Decousus et al105 published the first and only randomized study of vena caval filters in the prevention of PE. They randomized 400 patients using a 2 × 2 factorial design to a vena caval filter or no filter and enoxaparin or unfractionated heparin. Four different types of vena caval filters (titanium Greenfield, bird's nest, Vena Tech, and Cardial filters) were used. All were placed within 48 hours. Ventilation-perfusion scans were performed at baseline and after 8 to 12 days of anticoagulation. Vena caval filters were associated with a significant decrease in the incidence of PE compared with anticoagulation alone (1.1% versus 4.8%, P = .03) at 8 to 12 days of follow-up. After 2 years, however, this difference was no longer statistically significant although the trend still favored vena caval filters (3.4% versus 6.3%, P = .16). Symptomatic PE occurred at a similar frequency in both groups after 3 months (filter, 4; no filter, 6) (Figure 2). Fatal emboli were more common among patients treated solely with anticoagulation (0.5% versus 2.5%).105 

Fig. 2.

Cumulative percentage of patients suffering a symptomatic pulmonary embolism at 3, 12, and 24 months of follow-up.

Vena caval filters do not provide significantly greater protection against PE than anticoagulation alone. Decousus et al randomized 400 patients to receive a vena caval filter with anticoagulation or anticoagulation alone. Filters significantly reduced the incidence of PE at 8 to 12 days (P = .03). This protection was no longer significant after 2 years of follow-up (P = .16). Data adapted from Decousus et al.105 

Fig. 2.

Cumulative percentage of patients suffering a symptomatic pulmonary embolism at 3, 12, and 24 months of follow-up.

Vena caval filters do not provide significantly greater protection against PE than anticoagulation alone. Decousus et al randomized 400 patients to receive a vena caval filter with anticoagulation or anticoagulation alone. Filters significantly reduced the incidence of PE at 8 to 12 days (P = .03). This protection was no longer significant after 2 years of follow-up (P = .16). Data adapted from Decousus et al.105 

Close modal

In contrast, vena caval filters were associated with significantly more recurrent DVT than anticoagulation alone (20.8% versus 11.6%,P = .02) (Figure 3). No difference in bleeding or overall mortality was documented. Sixteen of the 37 patients (43.2%) with vena caval filters who had recurrent DVT also had IVCT (8% of filter population).105 

Fig. 3.

Cumulative percentage of patients with and without filters developing a DVT during follow-up.

Vena caval filter patients have a significantly higher cumulative incidence of recurrent DVT than patients receiving anticoagulation alone. By 24 months of follow-up, significantly more filter patients had developed a DVT (P = .02). Data adapted from Decousus et al.105 

Fig. 3.

Cumulative percentage of patients with and without filters developing a DVT during follow-up.

Vena caval filter patients have a significantly higher cumulative incidence of recurrent DVT than patients receiving anticoagulation alone. By 24 months of follow-up, significantly more filter patients had developed a DVT (P = .02). Data adapted from Decousus et al.105 

Close modal

In light of these data, one can conclude that vena caval filters in combination with standard anticoagulation do appear to offer significantly more protection from PE than anticoagulation alone. This additional protection, however, appears to be short-lived and does not decrease overall mortality. In addition, vena caval filters are associated with a higher incidence of recurrent DVT over 2 years of follow-up. Further follow-up of participants in this study should be highly informative, providing important information about the long-term risks and efficacy of vena caval filters in comparison with standard anticoagulation. Because almost all participants (94%) in this trial received anticoagulants for at least 3 months, however, the outcome of these patients cannot be generalized to the typical patient with a filter who does not receive anticoagulation.

Is anticoagulation necessary after vena caval filter placement?

If feasible, many investigators recommend routine anticoagulation after vena caval filter placement.106,107 However, little data are available to support the utility of this practice. Several case series have attempted to address this issue.14 31-33Although none of these investigators were able to demonstrate any benefit of anticoagulation, the retrospective, unrandomized nature of the studies as well as the limited duration and intensity of anticoagulation used in some of the studies suggest that randomized comparisons will be necessary to resolve this issue.

Are vena caval filters superior to anticoagulation for treatment of venous thromboembolism?

No randomized studies have been performed to address this question. The randomized study of Decousus et al105 suggests that filters may provide additional short-term protection against PE inanticoagulated patients but does not address the comparative efficacy of these therapies. An unrandomized retrospective case series found no significant differences in recurrence rate or lower extremity symptoms between the patients treated with anticoagulation and filters.36 Yet, the significant design flaws of this small study suggest that larger randomized trials will be required to answer this question conclusively.

Suprarenal vena caval filters

Concern about the possibility of IVCT precipitating acute renal failure has prompted many to recommend that vena caval filters be placed in the infrarenal portion of the inferior vena cava. Occasionally, however, placement below the renal veins is impossible. Six studies encompassing 187 patients have been published focusing on this subgroup (Table 3). All but 1 used Greenfield filters exclusively.5,11 108-111 Mean follow-up is 70 months. Follow-up data from chart reviews or clinic visits are available on 59%. Radiologic imaging was performed in 56%. PE occurred in 6% (7 of 112); venous insufficiency developed in 75% (55 of 73). Although IVCT was diagnosed in 3.6% (4 of 112), no evidence of significant renal morbidity was noted. Only 2 studies evaluated patients for DVT, which occurred in 3 participants (17.6%). Migration occurred in 18% (16 of 91) but all were asymptomatic.

Table 3.

Suprarenal vena caval filter studies

Study Patient no Chart/clinical F/U Radiology F/U Mean F/U duration PE IST/DVT IVCT Venous stasis
Stewart, 1982 Ref. 110  12  91%  58% 17 mo  1/11 (9%)  NA/2/11 (18%)  NA 1/11 (9%)  
Orsini, 1984 Ref. 11  11  100%  82% 12.3 mo  0  0  0  0  
Brenner, 1992 Ref. 5  100%  100%  12.5 mo  0  NA/1/6 (16.7%) 1/6 (16.7%) NA  
Greenfield, 1992 Ref. 109  71  85% 34%  53 mo  3/60 (5%)  NA  0/22 16/39 (41%) present prior to filter 
Greenfield, 1998 Ref. 108  148  49%  49%  81.6 mo 6/73 (8%)  NA  2/73 (2.7%)  55/73 (75%) 
Matchett, 1998 Ref. 111  22  100%  82%  36 mo 1/22 (4.5%)  NA  1/22 (4.5%)  NA 
Study Patient no Chart/clinical F/U Radiology F/U Mean F/U duration PE IST/DVT IVCT Venous stasis
Stewart, 1982 Ref. 110  12  91%  58% 17 mo  1/11 (9%)  NA/2/11 (18%)  NA 1/11 (9%)  
Orsini, 1984 Ref. 11  11  100%  82% 12.3 mo  0  0  0  0  
Brenner, 1992 Ref. 5  100%  100%  12.5 mo  0  NA/1/6 (16.7%) 1/6 (16.7%) NA  
Greenfield, 1992 Ref. 109  71  85% 34%  53 mo  3/60 (5%)  NA  0/22 16/39 (41%) present prior to filter 
Greenfield, 1998 Ref. 108  148  49%  49%  81.6 mo 6/73 (8%)  NA  2/73 (2.7%)  55/73 (75%) 
Matchett, 1998 Ref. 111  22  100%  82%  36 mo 1/22 (4.5%)  NA  1/22 (4.5%)  NA 

Abbreviations: F/U, follow-up; PE, recurrent pulmonary embolism; DVT, deep venous thrombosis; IST, insertion site thrombosis; IVCT, inferior vena cava thrombosis; NA, not assessed.

Note: Greenfield's 1998 publication is an update of a series of patients first reported by Stewart et al in 1982 and previously updated by Greenfield in 1992.

In comparison with data on infrarenal filters, suprarenal filters appear to have a higher rate of PE and venous insufficiency. Careful inspection suggests that these events probably reflect differences in the study populations rather than filter location. The mean follow-up in the suprarenal filter studies is considerably longer than the infrarenal group (70 versus 18 months). Previous PE and malignancies were more common among the population with suprarenal filters, suggesting that this study population was at particularly high risk for further thrombotic events and venous stasis.108 Therefore, further information will be required to clarify the comparative safety of suprarenal vena caval filters.

Superior vena caval filters

A few investigators have published small experiences with placement of filters in the superior vena cava (SVC). These studies consist of scattered case reports and a single small case series.112-117 Thus far the results have been mixed, with some patients remaining asymptomatic and others developing SVC thrombosis. Larger patient numbers and longer, more complete follow-up will be necessary before a conclusion can be made about the safety and efficacy of SVC filters.

Free-floating iliofemoral thrombus: an indication for an IVC filter?

A rare but commonly proposed indication for vena caval filter placement is the presence of a free-floating iliofemoral thrombus.118 In their retrospective review of 78 patients with venographically proven iliofemoral DVT treated with anticoagulation, Norris et al119 documented an extremely high risk of PE among patients with free-floating thrombi (60%). Several other retrospective studies have reached similar conclusions.120-124 In contrast, Pacouret et al recently reported no significant difference in the occurrence of PE between patients with (3.3%) or without (3.7%) free-floating iliofemoral thrombi treated with anticoagulation.125 Although differences in study patient populations may explain these conflicting conclusions, vena caval filters have yet to be demonstrated to be superior to anticoagulation in the treatment of these patients.

Vena caval filters for venous thromboembolic disease in other patient populations

A number of investigators have suggested that vena caval filters should be considered as first-line therapy for DVT and PE in patients with cancer as well as prophylaxis for PE in patients after trauma and with orthopedic problems. Although a considerable amount of literature has been devoted to examining the utility of filters in these settings, none of the studies are randomized and careful follow-up is often lacking.126-129 Vena caval filters have also been endorsed for treatment of DVT and PE in patients with limited cardiopulmonary reserve, chronic obstructive pulmonary disease, postpulmonary embolectomy, after renal or cardiac transplantation, and during pregnancy.118,130 Yet, only a small number of unrandomized reports exist to support these recommendations.6,7,17,28,131 132 Because viable alternative regimens are available for all of these situations, careful assessment of the efficacy and safety of vena caval filters in these settings is necessary before firm recommendations can be made.

Temporary or retrievable vena caval filters

Because the long-term safety of permanent vena caval filters remains unknown and many patients have only temporary contraindications to anticoagulation, there has been considerable interest in developing effective temporary filtration devices. Several under investigation include the Tempo filter and the Gunther Tulip filter. The cone-shaped Tempo filter is attached to a catheter, which is anchored in the subcutaneous tissue at the insertion site. It can be left in place for up to 6 weeks before removal.133 Preliminary studies in Europe have demonstrated it to be safe and effective.134The Gunther Tulip filter is a permanent vena caval filter, which can be retrieved if desired in the first 10 days after implantation. A small European study demonstrated an 80% success rate when retrieval was performed within 12 days.133 135 If proven safe and effective, these devices could be valuable tools in the treatment and prevention of venous thromboembolic disease.

The risks and benefits of anticoagulation for venous thromboembolic disease

Although significant safety concerns persist concerning the use of vena caval filters, an informed decision about their use must include a consideration of the risks and benefits of anticoagulation. The utility of anticoagulation in venous thromboembolic disease has been studied in numerous randomized trials involving thousands of patients worldwide. Long-term warfarin anticoagulation is associated with a rate of symptomatic recurrent thrombosis as low as 3% over 2 to 4 years of surveillance.136,137 Major hemorrhage (usually defined as an intracranial or retroperitoneal hemorrhage, one requiring a blood transfusion, or reducing baseline hemoglobin by 2 g/dL) occurs in approximately 3% of patients during heparin therapy (range, 0-7%) and 2% to 5% during subsequent warfarin anticoagulation.138,139 In patients on indefinite warfarin, Schulman et al137 noted major bleeding in 8.3% after 4 years of follow-up. A number of risk factors for bleeding have been identified, including duration of therapy, recent surgery or trauma, age above 65 years, concomitant aspirin therapy, renal or hepatic insufficiency, higher intensity therapy, previous gastrointestinal bleeding, alcohol abuse, and in some studies, malignant disease and female gender.138,139 Although these conditions increase the risk of anticoagulation, they are not viewed typically as absolute contraindications. On the other hand, most physicians would be hesitant to use anticoagulants in the setting of recent CNS trauma or hemorrhage, active bleeding, significant thrombocytopenia (less than 50 000/μL), cerebral metastases, or a recent large embolic stroke.140-142 Although scant research is available to justify these concerns, anecdotal case reports and series suggest that anticoagulation is probably sufficiently hazardous that vena caval filters should be considered for patients with venous thromboembolic disease in these situations.

Indications for vena caval filter placement

In light of the published data on vena caval filters and anticoagulation, what are appropriate indications for their use? Clearly, it is appropriate to consider placing a vena caval filter when an absolute contraindication to anticoagulation exists or when a life-threatening complication from anticoagulation arises. Table4 lists some common situations that would satisfy these criteria. Failure of anticoagulation is considered by many to be a reason for vena caval filter placement. Given their adverse effects, filters should be used judiciously for this indication. Objective documentation of thrombosis in the setting of adequate anticoagulation is essential. In the setting of warfarin resistance, Trousseau syndrome must be excluded. This hypercoagulable state associated with malignancies is characterized by disseminated intravascular coagulation and recurrent arterial or venous thrombotic events. Because thrombi develop throughout the vasculature, regional therapies such as vena caval filters are ineffective and may provide a nidus for clot formation. Heparin is the only useful therapy for Trousseau syndrome.143 Numerous other indications for vena caval filter placement have been endorsed; however, definitive evidence of their superiority to conventional care for these situations is lacking (Table 5).

Table 4.

Indications for a vena caval filter

1.  Absolute contraindication to anticoagulation 
   —CNS hemorrhage  
   —Overt gastrointestinal bleeding 
   —Retroperitoneal hemorrhage  
   —Massive hemoptysis 
   —Cerebral metastases 
   —Massive cerebrovascular accident  
   —CNS trauma 
   —Significant thrombocytopenia (<50,000/μL) 
 2.  Life-threatening hemorrhage on anticoagulation 
 3.  Failure of adequate anticoagulation 
1.  Absolute contraindication to anticoagulation 
   —CNS hemorrhage  
   —Overt gastrointestinal bleeding 
   —Retroperitoneal hemorrhage  
   —Massive hemoptysis 
   —Cerebral metastases 
   —Massive cerebrovascular accident  
   —CNS trauma 
   —Significant thrombocytopenia (<50,000/μL) 
 2.  Life-threatening hemorrhage on anticoagulation 
 3.  Failure of adequate anticoagulation 
Table 5.

Proposed indications for vena caval filter placement

 1.  Prophylaxis for PE in trauma patients 
 2.  Treatment of venous thromboembolism in cancer patients 
 3.  Prophylaxis for PE in high-risk orthopedic patients 
 4.  Pre- or postpulmonary embolectomy 
 5.  Prevention of PE in patients with extensive free-floating iliofemoral thrombi  
 6.  Prevention of PE in patients with chronic obstructive pulmonary disease and DVT 
 7.  Prevention of PE in patients with minimal cardiopulmonary reserve and DVT  
 8.  Treatment of venous thromboembolism in pregnancy  
 9.  Treatment of venous thromboembolism in organ transplant patients 
 1.  Prophylaxis for PE in trauma patients 
 2.  Treatment of venous thromboembolism in cancer patients 
 3.  Prophylaxis for PE in high-risk orthopedic patients 
 4.  Pre- or postpulmonary embolectomy 
 5.  Prevention of PE in patients with extensive free-floating iliofemoral thrombi  
 6.  Prevention of PE in patients with chronic obstructive pulmonary disease and DVT 
 7.  Prevention of PE in patients with minimal cardiopulmonary reserve and DVT  
 8.  Treatment of venous thromboembolism in pregnancy  
 9.  Treatment of venous thromboembolism in organ transplant patients 

Since the advent of modern venous interruption with the stainless steel Greenfield filter in 1973, numerous clinical studies have been performed to assess the utility of vena caval filters in the treatment of venous thromboembolic disease. Unfortunately, virtually all of these studies have been unrandomized case series with follow-up of short duration and limited intensity. Consequently, although these devices appear to be effective in the prevention of PE, this conclusion must be considered preliminary. Furthermore, troubling concerns about the safety of these devices remain. Studies have linked filters with an increased risk of DVT, IVCT, and perhaps, postphlebitic syndrome. In the absence of randomized studies, no filter can claim superiority in effectiveness or safety over other filters or standard anticoagulation.

Because long-term safety and efficacy of filters remain uncertain, use of filters should be restricted to situations in which anticoagulation is clearly contraindicated. More liberal application of vena caval filters should be restricted to prospective randomized clinical trials. Undoubtedly, vena caval filters represent an important weapon in every clinician's armamentarium for the treatment of venous thromboembolic disease, but the optimal application of this technology remains to be defined. Temporary filtration devices in clinical testing may provide many of the advantages of permanent filters without the potential long-term side effects.133,134 Carefully designed, prospective, randomized trials are needed to establish the safety and utility of both classes of vena caval filtration devices. New guidelines for vena caval filter placement and patient follow-up suggest that there is considerable interest within the clinical research community to initiate such studies.3 Until these studies are performed, the true potential and problems of vena caval filters will remain unknown.

The author would like to acknowledge Michael Linkenhoker, MA, for his vena caval filter illustrations. The author also would like to thank Drs Paul Bray, Chi V. Dang, Jerry L. Spivak, and William R. Bell for their advice.

Reprints:Michael B. Streiff, Division of Hematology, Department of Medicine, Johns Hopkins University School of Medicine, Ross Research Bldg, Room 1025, 720 Rutland Ave, Baltimore, MD 21205; e-mail: mstreiff@jhmi.edu.

The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked “advertisement” in accordance with 18 U.S.C. section 1734.

1
Bick
 
RL
Hereditary and acquired thrombophilia: preface.
Semin Thromb Hemost.
25
1999
251
253
2
Levine
 
M
Raskob
 
GE
Landefeld
 
CS
Kearon
 
C
Hemorrhagic complications of anticoagulant treatment.
Chest.
114
1998
511S
523S
3
Greenfield
 
LJ
Rutherford
 
RB
participants in the Vena Caval Filter Consensus Conference
Recommended reporting standards for vena caval filter placement and patient follow-up.
J Vasc Interv Radiol.
10
1999
1013
1019
4
Cho
 
KJ
Greenfield
 
LJ
Proctor
 
MC
et al
Evaluation of a new percutaneous stainless steel Greenfield filter.
J Vasc Interv Radiol.
8
1997
181
187
5
Brenner
 
DW
Brenner
 
CJ
Scott
 
J
Wehberg
 
K
Granger
 
JP
Schellhammer
 
PF
Suprarenal Greenfield filter placement to prevent pulmonary embolus in patients with vena caval tumor thrombi.
J Urol.
147
1992
19
23
6
Hux
 
CH
Wapner
 
RJ
Chayen
 
B
Rattan
 
P
Jarrell
 
B
Greenfield
 
L
Use of the Greenfield filter for thromboembolic disease in pregnancy.
Am J Obstet Gynecol.
155
1986
734
737
7
Pomper
 
SR
Lutchman
 
G
The role of intracaval filters in patients with COPD and DVT.
Angiology.
42
1991
85
89
8
Tobin
 
KD
Pais
 
SO
Austin
 
CB
Femoral vein thrombosis following percutaneous placement of the Greenfield filter.
Invest Radiol.
24
1989
442
445
9
Welch
 
TJ
Stanson
 
AW
Sheedy
 
PF
Johnson
 
CM
Miller
 
WE
Johnson
 
CD
Percutaneous placement of the Greenfield vena caval filter.
Mayo Clin Proc.
63
1988
343
347
10
Kolachalam
 
RB
Julian
 
TB
Clinical presentation of thrombosed Greenfield filters.
Vasc Surg.
24
1990
666
670
11
Orsini
 
RA
Jarrell
 
BE
Suprarenal placement of vena caval filters: indications, techniques and results.
J Vasc Surg.
1
1984
124
135
12
Gomez
 
GA
Cutler
 
BS
Wheeler
 
HB
Transvenous interruption of the inferior vena cava.
Surgery.
93
1983
612
619
13
Kantor
 
A
Glanz
 
S
Gordon
 
DH
Sclafani
 
SJA
Percutaneous insertion of the Kimray-Greenfield filter: incidence of femoral vein thrombosis.
Am J Roentgenol.
149
1987
1065
1066
14
Ortega
 
M
Gahtan
 
V
Roberts
 
A
Matsumoto
 
T
Kerstein
 
M
Efficacy of anticoagulation post-inferior vena caval filter placement.
Am Surg.
64
1998
419
423
15
Cimochowski
 
GE
Evans
 
RH
Zarins
 
CK
Lu
 
CT
DeMeester
 
TR
Greenfield filter versus Mobin-Uddin umbrella: the continuing quest for the ideal method of vena caval interruption.
J Thorac Cardiovasc Surg.
79
1980
358
365
16
Greenfield
 
LJ
Proctor
 
MC
Twenty-year clinical experience with the Greenfield filter.
Cardiovasc Surg.
3
1995
199
205
17
Golueke
 
PJ
Garrett
 
WV
Thompson
 
JE
Smith
 
BL
Talkington
 
CM
Interruption of the vena cava by means of the Greenfield filter: expanding the indications.
Surgery.
103
1988
111
117
18
Fink
 
JA
Jones
 
BT
The Greenfield filter as the primary means of therapy in venous thromboembolic disease.
Surg Gynecol Obstet.
172
1991
253
256
19
Rose
 
BS
Simon
 
DC
Hess
 
ML
Van Aman
 
ME
Percutaneous transfemoral placement of the Kimray-Greenfield vena cava filter.
Radiology.
165
1987
373
376
20
Todd
 
GJ
Sanderson
 
J
Nowygrod
 
R
Benvenisty
 
A
Reemtsma
 
K
Recent clinical experience with the vena cava filter.
Am J Surg.
156
1988
353
358
21
Berland
 
LL
Maddison
 
FE
Bernhard
 
VM
Radiologic follow-up of vena cava filter devices.
Am J Roentgenol.
134
1980
1047
1052
22
Scurr
 
JH
Jarrett
 
PEM
Wastell
 
C
The treatment of recurrent pulmonary embolism: experience with the Kimray-Greenfield vena cava filter.
Ann R Coll Surg Engl.
65
1983
233
234
23
Hye
 
RJ
Mitchell
 
AT
Dory
 
CE
Freischlag
 
JA
Roberts
 
AC
Analysis of the transition to percutaneous placement of Greenfield filters.
Arch Surg.
125
1990
1550
1553
24
Sullivan
 
TM
Martinez
 
BD
Lemmon
 
G
Clark
 
PM
Schwartz
 
RA
Bondy
 
B
Clinical experience with the Greenfield filter in 193 patients and description of a new technique for operative insertion [see comments].
J Am Coll Surg.
178
1994
117
122
25
Alexander
 
JJ
Yuhas
 
JP
Piotrowski
 
JJ
Is the increasing use of prophylactic percutaneous IVC filters justified?
Am J Surg.
168
1994
102
106
26
Pais
 
SO
Tobin
 
KD
Austin
 
CB
Queral
 
L
Percutaneous insertion of the Greenfield inferior vena cava filter: experience with ninety-six patients.
J Vasc Surg.
8
1988
460
464
27
Richenbacher
 
WE
Atnip
 
RG
Campbell
 
DB
Waldhausen
 
JA
Recurrent pulmonary embolism after inferior vena caval interruption with a Greenfield filter.
World J Surg.
13
1989
623
628
28
Rohrer
 
MJ
Scheidler
 
MG
Wheeler
 
HB
Cutler
 
BS
Extended indications for placement of an inferior vena cava filter [see comments].
J Vasc Surg.
10
1989
44
49
29
Carabasi
 
RA
Moritz
 
MJ
Jarrell
 
BE
Complications encountered with the use of the Greenfield filter.
Am J Surg.
154
1987
163
168
30
Greenfield
 
LJ
Peyton
 
R
Crute
 
S
Barnes
 
R
Greenfield vena caval filter experience: late results in 156 patients.
Arch Surg.
116
1981
1451
1456
31
Greenfield
 
LJ
Michna
 
BA
Twelve-year clinical experience with the Greenfield vena caval filter.
Surgery.
104
1988
706
712
32
Lang
 
W
Schweiger
 
H
Hofmann-Preiss
 
K
Results of long-term venacavography study after placement of a Greenfield vena caval filter.
J Cardiovasc Surg.
33
1992
573
578
33
Jones
 
B
Fink
 
JA
Donovan
 
DL
Sharp
 
WV
Analysis of benefit of anticoagulation after placement of Kimray-Greenfield filter.
Surg Gynecol Obstet.
169
1989
400
402
34
Braverman
 
SJ
Battey
 
PM
Smith
 
RB
Vena caval interruption.
Am Surg.
58
1992
188
192
35
Hlavaty
 
TS
McCowan
 
TC
Ferris
 
EJ
Carver
 
DL
Barnes
 
RW
Experience with the Kimray-Greenfield inferior vena caval filter.
J Ark Med Soc.
88
1991
215
217
36
Jones
 
BT
Fink
 
JA
A prospective comparison of the status of the deep venous system after treatment with intracaval interruption versus anticoagulation.
J Am Coll Surg.
178
1994
220
222
37
Wells
 
PS
Kovacs
 
MJ
Bormanis
 
J
et al
Expanding eligibility for outpatient treatment of deep venous thrombosis and pulmonary embolism with low molecular weight heparin: a comparison of patient self-injection with homecare injection.
Arch Intern Med.
158
1998
1809
1812
38
Anonymous
Low-molecular weight heparin in the treatment of patients with venous thromboembolism: The Columbus Investigators.
N Engl J Med.
337
1997
657
662
39
Simonneau
 
G
Sors
 
H
Charbonnier
 
B
et al
A comparison of low-molecular weight heparin with unfractionated heparin for acute pulmonary embolism: The THESEE Study group.
N Engl J Med.
337
1997
663
669
40
Koopman
 
MMW
Prandoni
 
P
Piovella
 
F
et al
Treatment of venous thrombosis with intravenous unfractionated heparin administered in the hospital as compared with subcutaneous low-molecular weight heparin administered at home.
N Engl J Med.
334
1996
682
687
41
Prandoni
 
P
Lensing
 
AWA
Buller
 
HR
et al
Comparison of subcutaneous low-molecular weight heparin with intravenous standard heparin in proximal deep-vein thrombosis.
Lancet.
339
1992
441
445
42
Levine
 
M
Gent
 
M
Hirsh
 
J
et al
A comparison of low-molecular weight heparin administered primarily at home with unfractionated heparin administered in the hospital for proximal deep-vein thrombosis.
N Engl J Med.
334
1996
677
681
43
Hull
 
RD
Raskob
 
GE
Pineo
 
GF
et al
Subcutaneous low-molecular weight heparin compared with continuous intravenous heparin in the treatment of proximal-vein thrombosis.
N Engl J Med.
326
1992
975
982
44
Harris
 
EJJ
Kinney
 
EV
Harris
 
EJS
Olcott
 
C
Zarins
 
CK
Phlegmasia complicating prophylactic percutaneous inferior vena caval interruption: a word of caution.
J Vasc Surg.
22
1995
606
611
45
Feinman
 
LJ
Meltzer
 
AJ
Phlegmasia cerulea dolens as a complication of percutaneous insertion of a vena caval filter.
J Am Osteopath Assoc.
89
1989
63
68
46
Magnant
 
JG
Walsh
 
DB
Juravsky
 
LI
Cronenwett
 
JL
Current use of inferior vena cava filters.
J Vasc Surg.
16
1992
701
706
47
Tardy
 
B
Mismetti
 
P
Page
 
Y
et al
Symptomatic inferior vena cava filter thrombosis: clinical study of 30 consecutive cases.
Eur Respir J.
9
1996
2012
2016
48
Crochet
 
DP
Stora
 
O
Ferry
 
D
et al
Vena Tech-LGM filter: long-term results of a prospective study.
Radiology.
188
1993
857
860
49
Gurewich
 
G
Thomas
 
DP
Rabinov
 
KR
Pulmonary embolism after ligation of the inferior vena cava.
N Engl J Med.
274
1966
1350
1354
50
Piccone
 
VA
Vidal
 
E
Yarnoz
 
M
et al
The late results of caval ligation.
Surgery.
68
1970
980
998
51
Kim
 
D
Edelman
 
RR
Margolin
 
CJ
et al
The Simon nitinol filter: evaluation by MR and ultrasound.
Angiology.
43
1992
541
548
52
Miller
 
CL
Wechsler
 
RJ
CT evaluation of Kimray-Greenfield filter complications.
Am J Roentgenol.
147
1986
45
50
53
Bianchini
 
AU
Mehta
 
SN
Mulder
 
DS
Barkun
 
AN
Mayrand
 
S
Duodenal perforation by a Greenfield filter: endoscopic diagnosis.
Am J Gastroenterol.
92
1997
686
687
54
Lang
 
W
Schweiger
 
H
Fietkau
 
R
Hofmann-Preiss
 
K
Spontaneous disruption of two Greenfield filters.
Radiology.
174
1990
445
446
55
Dabbagh
 
A
Chakfe
 
N
Kretz
 
JG
et al
Late complication of a Greenfield filter associating caudal migration and perforation of the abdominal aorta by a ruptured strut.
J Vasc Surg.
22
1995
182
187
56
Goldman
 
HB
Hanna
 
K
Dmochowski
 
RR
Ureteral injury secondary to an inferior vena caval filter.
J Urol.
156
1996
1763
57
Goldman
 
KA
Adelman
 
MA
Retroperitoneal caval filter as a source of abdominal pain.
Cardiovasc Surg.
2
1994
85
87
58
Gelbfish
 
GA
Ascer
 
E
Intracardiac and intrapulmonary Greenfield filters: a long-term follow-up.
J Vasc Surg.
14
1991
614
617
59
James
 
KV
Sobolewski
 
AP
Lohr
 
JM
Welling
 
RE
Tricuspid insufficiency after intracardiac migration of a Greenfield filter: case report and review of the literature.
J Vasc Surg.
24
1996
494
498
60
Katsamouris
 
AA
Waltman
 
AC
Delichatsios
 
MA
Athanasoulis
 
CA
Inferior vena cava filters: in vitro comparison of clot trapping and flow dynamics.
Radiology.
166
1988
361
366
61
Thompson
 
BH
Cragg
 
AH
Smith
 
TP
Bareniewski
 
H
Barnhart
 
WH
De Jong
 
SC
Thrombus-trapping efficiency of the Greenfield filter in vivo.
Radiology.
172
3 pt 2
1989
979
981
62
Greenfield
 
LJ
Proctor
 
MC
Experimental embolic capture by asymmetric Greenfield filters.
J Vasc Surg.
16
1992
436
443
63
Prandoni
 
P
Villalta
 
S
Bagatella
 
P
et al
The clinical course of deep-vein thrombosis: prospective long-term follow-up of 528 symptomatic patients.
Haematologica.
82
1997
423
428
64
Saarinen
 
J
Sisto
 
T
Laurikka
 
J
et al
Late sequelae of acute deep venous thrombosis: evaluation five and ten years after.
Phlebology.
10
1995
106
109
65
Greenfield
 
LJ
Cho
 
KJ
Pais
 
SO
Van Aman
 
M
Preliminary clinical experience with the titanium Greenfield vena caval filter.
Arch Surg.
124
1989
657
659
66
Teitelbaum
 
GP
Jones
 
DL
van Breda
 
A
et al
Vena caval filter splaying: potential complication of use of the titanium Greenfield filter.
Radiology.
173
1989
809
814
67
Ramchandani
 
P
Koolpe
 
HA
Zeit
 
RM
Splaying of titanium Greenfield inferior vena caval filter.
Am J Roentgenol.
155
1990
1103
1104
68
Greenfield
 
LJ
Cho
 
KJ
Proctor
 
MC
et al
Results of a multicenter study of the modified-hook titanium Greenfield filter.
J Vasc Surg.
14
1991
253
257
69
Greenfield
 
LJ
Proctor
 
MC
Cho
 
KJ
et al
Extended evaluation of the titanium Greenfield vena caval filter [published erratum appears in J Vasc Surg 1995;21:162].
J Vasc Surg.
20
1994
458
464
70
Thomas
 
LA
Summers
 
RR
Cardwell
 
MS
Use of Greenfield filters in pregnant women at risk for pulmonary embolism.
South Med J.
90
1997
215
217
71
Mohan
 
CR
Hoballah
 
JJ
Sharp
 
WJ
Kresowik
 
TF
Lu
 
CT
Corson
 
JD
Comparative efficacy and complications of vena caval filters.
J Vasc Surg.
21
1995
235
245
72
Ferris
 
EJ
McCowan
 
TC
Carver
 
DK
McFarland
 
D
Percutaneous inferior vena caval filters: follow-up of seven designs in 320 patients.
Radiology.
188
1993
851
856
73
Molgaard
 
CP
Yucel
 
EKGSC
et al
Access-site thrombosis after placement of inferior vena cava filters with 12-14F delivery sheaths.
Radiology.
185
1992
257
261
74
Aswad
 
MA
Sandager
 
GP
Pais
 
SO
et al
Early duplex scan evaluation of four vena caval interruption devices.
J Vasc Surg.
24
1996
809
818
75
Wittenberg
 
G
Kueppers
 
V
Tschammler
 
A
et al
Long-term results of vena cava filters: experiences with the LGM and the titanium Greenfield devices.
Cardiovasc Interv Radiol.
21
1998
225
229
76
Blebea
 
J
Wilson
 
R
Waybill
 
P
et al
Deep venous thrombosis after percutaneous insertion of vena caval filters.
J Vasc Surg.
30
1999
821
829
77
Simon
 
M
Rabkin
 
DJ
Kleshinski
 
S
Kim
 
D
Ransil
 
BJ
Comparative evaluation of clinically available inferior vena cava filters with an in vitro physiologic simulation of the vena cava.
Radiology.
189
1993
769
774
78
Millward
 
SF
Marsh
 
JI
Pon
 
C
Moher
 
D
Thrombus-trapping efficiency of the LGM (Vena Tech) and titanium Greenfield filters in vivo.
J Vasc Interv Radiol.
3
1992
103
106
79
Greenfield
 
LJ
Proctor
 
MC
Cho
 
KJ
Wakefield
 
TW
Limb asymmetry in titanium Greenfield filters: clinically significant?
J Vasc Surg.
26
1997
770
775
80
Roehm
 
JOJ
The bird's nest filter: a new percutaneous transcatheter inferior vena cava filter.
J Vasc Surg.
1
1984
498
501
81
Roehm
 
JOJ
Johnsrude
 
IS
Barth
 
MH
Gianturco
 
C
The bird's nest inferior vena cava filter: progress report.
Radiology.
168
1988
745
749
82
Dorfman
 
GS
Percutaneous inferior vena caval filters.
Radiology.
174
1990
987
992
83
Smith
 
JA
Atkinson
 
NR
Walters
 
NA
Thomson
 
KR
Early experience with the bird's nest inferior vena-caval filter [letter].
Med J Aust.
150
1989
164
165
84
Thomas
 
JH
Cornell
 
KM
Siegel
 
EL
Sparks
 
C
Rosenthal
 
SJ
Vena caval occlusion after bird's nest filter placement.
Am J Surg.
176
1998
598
600
85
Martin
 
B
Martyak
 
TE
Stoughton
 
TL
Collazo
 
WA
Pearl
 
W
Experience with the Gianturco-Roehm bird's nest vena cava filter.
Am J Cardiol.
66
1990
1275
1277
86
Firkin
 
A
Walters
 
N
Thomson
 
K
Atkinson
 
N
Inferior vena cava “birds nest” filters—2 year follow-up.
Australas Radiol.
36
1992
286
288
87
Lord
 
RS
Benn
 
I
Early and late results after Bird's nest filter placement in the inferior vena cava: clinical and duplex ultrasound follow up.
Aust N Z J Surg.
64
1994
106
114
88
Wojtowycz
 
MM
Stoehr
 
T
Crummy
 
AB
McDermott
 
JC
Sproat
 
IA
The bird's nest inferior vena caval filter: review of a single-center experience.
J Vasc Interv Radiol.
8
1997
171
179
89
Starok
 
MS
Common
 
AA
Follow-up after insertion of bird's nest inferior vena caval filters.
Can Assoc Radiol J.
47
1996
189
194
90
Reed
 
RA
Teitelbaum
 
GP
Taylor
 
FC
Pentecost
 
MJ
Roehm
 
JO
Use of the bird's nest filter in oversized inferior venae cavae.
J Vasc Interv Radiol.
2
1991
447
450
91
Hicks
 
ME
Middleton
 
WD
Picus
 
D
Darcy
 
MD
Kleinhoffer
 
MA
Prevalence of local venous thrombosis after transfemoral placement of a bird's nest vena caval filter.
J Vasc Interv Radiol.
1
1990
63
68
92
Young
 
N
Clinical follow-up of patients with percutaneously inserted inferior vena caval filters.
Australas Radiol.
39
1995
233
236
93
Simon
 
M
Athanasoulis
 
CA
Kim
 
D
et al
Simon nitinol inferior vena cava filter: initial clinical experience: work in progress.
Radiology.
172
1989
99
103
94
Poletti
 
PA
Becker
 
CD
Prina
 
L
et al
Long-term results of the Simon nitinol inferior vena cava filter.
Eur Radiol.
8
1998
289
294
95
McCowan
 
TC
Ferris
 
EJ
Carver
 
DK
Molpus
 
WM
Complications of the nitinol vena caval filter.
J Vasc Interv Radiol.
3
1992
401
408
96
Hawkins
 
SP
al-Kutoubi
 
A
The Simon nitinol inferior vena cava filter: preliminary experience in the UK.
Clin Radiol.
46
1992
378
380
97
Murphy
 
TP
Dorfman
 
GS
Yedlicka
 
JW
et al
LGM vena cava filter: objective evaluation of early results.
J Vasc Interv Radiol.
2
1991
107
115
98
Taylor
 
FC
Awh
 
MH
Kahn
 
CEJ
Lu
 
CT
Vena Tech vena cava filter: experience and early follow-up.
J Vasc Interv Radiol.
2
1991
435
440
99
Cull
 
DL
Wheeler
 
JR
Gregory
 
RT
Synder
 
SOJ
Gayle
 
RG
Parent
 
FN
The Vena Tech filter: evaluation of a new inferior vena cava interruption device.
J Cardiovasc Surg (Torino).
32
1991
691
696
100
Ricco
 
JB
Crochet
 
D
Sebilotte
 
P
et al
Percutaneous transvenous caval interruption with the LGM filter: early results of a multicenter trial.
Ann Vasc Surg.
3
1988
242
247
101
Ricco
 
JB
Dubreuil
 
F
Reynaud
 
P
et al
The LGM Vena-Tech caval filter: results of a multicenter study.
Ann Vasc Surg.
9(suppl)
1995
S89
S100
102
Millward
 
SF
Marsh
 
JI
Peterson
 
RA
et al
LGM (Vena Tech) vena cava filter: clinical experience in 64 patients.
J Vasc Interv Radiol.
2
1991
429
433
103
Millward
 
SF
Peterson
 
RA
Moher
 
D
et al
LGM (Vena Tech) vena caval filter: experience at a single institution.
J Vasc Interv Radiol.
5
1994
351
356
104
Crochet
 
DP
Brunel
 
P
Trogrlic
 
S
Grossetete
 
R
Auget
 
JL
Dary
 
C
Long-term follow-up of Vena Tech-LGM filter: predictors and frequency of caval occlusion.
J Vasc Interv Radiol.
10
1999
137
142
105
Decousus
 
H
Leizorovicz
 
A
Parent
 
F
et al
A clinical trial of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep-vein thrombosis. Prevention du Risque d'Embolie Pulmonaire par Interruption Cave Study Group.
N Engl J Med.
338
1998
409
415
106
Ballew
 
KA
Philbrick
 
JT
Becker
 
DM
Vena cava filter devices.
Clin Chest Med.
16
1995
295
305
107
Kanter
 
B
Moser
 
KM
The Greenfield vena cava filter.
Chest.
93
1988
170
175
108
Greenfield
 
LJ
Proctor
 
MC
Suprarenal filter placement.
J Vasc Surg.
28
1998
432
438
109
Greenfield
 
LJ
Cho
 
KJ
Proctor
 
MC
et al
Late results of suprarenal Greenfield vena caval filter placement.
Arch Surg.
127
1992
969
973
110
Stewart
 
JR
Peyton
 
JWR
Crute
 
S
Greenfield
 
LJ
Clinical results of suprarenal placement of the Greenfield vena cava filter.
Surgery.
92
1982
1
4
111
Matchett
 
WJ
Jones
 
MP
McFarland
 
DR
Ferris
 
EJ
Suprarenal vena caval filter placement: follow-up of four filter types in 22 patients.
J Vasc Interv Radiol.
9
1998
588
593
112
Owen
 
EWJ
Schoettle
 
GPJ
Harrington
 
OB
Placement of a Greenfield filter in the superior vena cava.
Ann Thorac Surg.
53
1992
896
897
113
Ascer
 
E
Gennaro
 
M
Lorensen
 
E
Pollina
 
RM
Superior vena caval Greenfield filters: indications, techniques, and results.
J Vasc Surg.
23
1996
498
503
114
Hoffman
 
MJ
Greenfield
 
LJ
Central venous septic thrombosis managed by superior vena cava Greenfield filter and venous thrombectomy: a case report.
J Vasc Surg.
4
1986
606
611
115
Pais
 
SO
Orchis
 
DF
Mirvis
 
SE
Superior vena caval placement of Kimray-Greenfield filter.
Radiology.
165
1987
385
386
116
Black
 
MD
French
 
GJ
Rasuli
 
P
Bouchard
 
AC
Upper extremity deep venous thrombosis: underdiagnosed and potentially lethal.
Chest.
103
1993
1887
1890
117
Lidagoster
 
MI
Widman
 
WD
Chevinski
 
AH
Superior vena caval occlusion after filter insertion.
J Vasc Surg.
20
1994
158
159
118
Jones
 
TK
Barnes
 
RW
Greenfield
 
LJ
Greenfield vena caval filter: rationale and current indications.
Ann Thorac Surg.
42(suppl 6)
1986
S48
S55
119
Norris
 
CS
Greenfield
 
LJ
Herrmann
 
JB
Free-floating iliofemoral thrombus: a risk of pulmonary embolism.
Arch Surg.
120
1985
806
808
120
Radomski
 
JS
Jarrell
 
BE
Carabasi
 
RA
Yang
 
S-L
Koolpe
 
H
Risk of pulmonary embolus with inferior vena cava thrombosis.
Am Surg.
53
1987
97
101
121
Berry
 
RE
George
 
JE
Shaver
 
WA
Free-floating thrombus: a retrospective analysis.
Ann Surg.
211
1990
719
723
122
Voet
 
D
Afschrift
 
M
Floating thrombi: diagnosis and follow-up by duplex ultrasound.
Br J Radiol.
64
1991
1010
1014
123
Baldridge
 
ED
Martin
 
MA
Welling
 
RE
Clinical significance of free-floating venous thrombi.
J Vasc Surg.
11
1990
62
69
124
Monreal
 
M
Ruiz
 
J
Salvador
 
R
et al
Recurrent pulmonary embolism: a prospective study.
Chest.
95
1989
976
979
125
Pacouret
 
G
Alison
 
D
Pottier
 
J-M
et al
Free-floating thrombus and embolic risk in patients with angiographically confirmed proximal deep venous thrombosis: a prospective study.
Arch Int Med.
157
1997
305
308
126
Cohen
 
JR
Grella
 
L
Citron
 
M
Greenfield filter instead of heparin as primary treatment for deep venous thrombosis or pulmonary embolism in patients with cancer.
Cancer.
70
1992
1993
1996
127
Rogers
 
FB
Venous thromboembolism in trauma patients.
Surg Clin North Am.
75
1995
279
291
128
Rodriguez
 
JL
Lopez
 
JM
Proctor
 
MC
et al
Early placement of prophylactic vena caval filters in injured patients at high risk for pulmonary embolism.
J Trauma.
40
1996
797
802
129
Rogers
 
FB
Shackford
 
SR
Ricci
 
MA
Huber
 
BM
Atkins
 
T
Prophylactic vena cava filter insertion in selected high-risk orthopaedic trauma patients.
J Orthop Trauma.
11
1997
267
272
130
Bergqvist
 
D
The role of vena caval interruption in patients with venous thromboembolism.
Prog Cardiovasc Dis.
37
1994
25
37
131
Greenfield
 
LJ
Scher
 
LA
Elkins
 
RC
KMA-Greenfield filter placement for chronic pulmonary hypertension.
Ann Surg.
189
1979
560
565
132
Greenfield
 
LJ
Peyton
 
MD
Brown
 
PP
Elkins
 
RC
Transvenous management of pulmonary embolic disease.
Ann Surg.
180
1974
461
468
133
Millward
 
SF
Temporary and retrievable inferior vena cava filters: current status.
J Vasc Interv Radiol.
9
1998
381
387
134
Bovyn
 
G
Gory
 
P
Reynaud
 
P
Ricco
 
JB
The Tempofilter: a multicenter study of a new temporary caval filter implantable for up to six weeks.
Ann Vasc Surg.
11
1997
520
528
135
Ponchon
 
M
Goffette
 
P
Hainaut
 
P
Temporary vena caval filtration: preliminary clinical experience with removable vena caval filters.
Acta Clinica Belgica.
54
1999
223
228
136
Kearon
 
C
Gent
 
M
Hirsh
 
J
et al
A comparison of three months of anticoagulation with extended anticoagulation for a first episode of idiopathic venous thromboembolism.
N Engl J Med.
340
1999
901
907
137
Schulman
 
S
Granqvist
 
S
Holmstrom
 
M
et al
The duration of oral anticoagulant therapy after a second episode of venous thromboembolism: The Duration of Anticoagulation Trial Study Group.
N Engl J Med.
336
1997
393
398
138
Levine
 
M
Gent
 
M
Hirsh
 
J
et al
A comparison of low-molecular weight heparin administered primarily at home with unfractionated heparin administered in the hospital for proximal deep-vein thrombosis.
N Engl J Med.
334
1996
677
681
139
White
 
RH
Beyth
 
RJ
Zhou
 
H
Romano
 
PS
Major bleeding after hospitalization for deep venous thrombosis.
Am J Med.
107
1999
414
424
140
Brathwaite
 
CE
Mure
 
AJ
O'Malley
 
KF
Spence
 
RK
Ross
 
SE
Complications of anticoagulation for pulmonary embolism in low risk trauma patients.
Chest.
104
1993
718
720
141
Olin
 
JW
Young
 
JR
Graor
 
RA
Ruschhaupt
 
WF
Beven
 
EG
Bay
 
JW
Treatment of deep vein thrombosis and pulmonary emboli in patients with primary and metastatic brain tumors.
Arch Intern Med.
147
1987
2177
2179
142
Cerebral Embolism Study Group
Immediate anticoagulation of embolic stroke: brain hemorrhage and management options.
Stroke.
15
1984
779
789
143
Bell
 
WR
Starksen
 
NF
Tong
 
S
Porterfield
 
JK
Trousseau's syndrome: devastating coagulopathy in the absence of heparin.
Am J Med.
79
1985
423
430
Sign in via your Institution