Outcome and complications of retrievable inferior vena cava filters

Influence of Exercise on Inferior Vena Cava Wall Interaction with Inferior Vena Cava Filters: Results of a Pilot In Vivo Porcine Study

Purpose The aim of this study was to assess the effect of mild exercise on inferior vena cava (IVC) filter interaction with imaging and pathological features with the neighboring vessel wall utilizing a porcine model.

Methods After Institutional Animal Care and Use Committee (IACUC) approval, retrievable Option Elite IVC filters were implanted in six Yorkshire pigs utilizing the right common femoral vein approach under general anesthesia. Group A (n = 4) pigs remained sedentary for 4 weeks. Group B (n = 2) pigs were exercised using a harness and treadmill for 10 minutes/day for 4 days/week. At approximately 4 weeks, IVC venograms were performed and the pigs were sacrificed. After laparotomy, the IVC was ligated above and below the filter, excised and fixed in formalin. Gross and histological examination of the IVC was performed. Gross images of each sample were captured before removal of the filters. One longitudinal, one tangential, and five transverse representative sections were processed for paraffin sectioning and hematoxylin and eosin slides were prepared. A pathologist examined all tissues to assess differences between normal vein, group A and group B pigs. The pathologist provided an overall assessment and representative images.

Results All IVC filter implantations were technically successful without adverse effects. There was no incidence of caval thrombosis, filter strut fracture, or filter migration in either group. On gross pathological examination, IVC of the pigs in group B demonstrated more perivascular and mural fibrosis than those pigs in group A. Histopathological findings correlated with gross findings.

Conclusions In this pilot study, there were no incidence of IVC filter strut fracture, penetration or IVC occlusion in sedentary or exercised pigs. However, there tended to be more perivascular and mural fibrosis on pathological examination of inferior vena cavas from exercised pigs. Further larger scale studies may employ the porcine model to further understand the role exercise may play on IVC filter and caval wall interaction.

An expert spotlight on inferior vena cava filters

Introduction: Inferior vena cava (IVC) filters are mechanical filtration devices designed as an alternative to surgical ligation/plication of the IVC. Their use has been controversial, especially with the introduction of retrievable filters and expanded/prophylactic indications.Areas covered: Authors discuss the types of available IVC filters, indications for placement, evidence on their effectiveness in general and specific patient populations, procedural considerations, off-label use, complications, and filter retrieval. This review is based on manuscripts/abstracts published from 1960 to 2021 on venous thromboembolism and IVC filters.Expert opinion: Despite the limited data on their effectiveness and survival benefit, IVC filters continue to play an important role in the treatment of patients with venous thromboembolism (VTE) who cannot receive standard anticoagulation. There is no role of IVC filters in patients without VTE. While retrievable filters are desirable for short-term use, a dedicated team-based approach, and advanced training are required for their successful removal. Newer devices are promising in improving patient safety . The device manufacturers and regulatory agencies should consider specific approaches to track device-related adverse events. Population-based studies are required to establish optimal patient population who would benefit from these devices. .

Persistent Abdominal Pain as Rare Complication of Duodenal Perforation From an Inferior Vena Cava Filter

Deep vein thrombosis (DVT) continues to be a significant source of morbidity for surgical patients. Inferior vena cava (IVC) filter placement is indicated for DVT in patients who have contraindications to anticoagulation or anticoagulation failure. Over the last decade, there is an exponential increase in IVC filter placement with increased complications reported. These include IVC penetration, IVC occlusion, insertion complication and filter migration. We report a rare case of symptomatic duodenal perforation by an IVC filter migration. This case illustrates that even though IVC migration and perforation is a rare complication, it should be recognized as a potential cause for gastrointestinal (GI) symptoms in these patients.

Inferior vena cava filter – comprehensive overview of current indications, techniques, complications and retrieval rates

Summary: Inferior vena cava (IVC) filter has been used to manage patients with pulmonary embolism and deep venous thrombosis. Its ease of use and the expansion of relative indications have led to a dramatic increase in IVC filter placement. However, IVC filters have been associated with a platitude of complications. Therefore, there exists a need to examine the current indications and identify the patient population at risk. In this paper, we comprehensively reviewed the current indications and techniques of IVC filter placement. Further, we examined the various complications associated with either permanent or retrievable IVC filters. Lastly, we examined the current data on filter retrieval.

Functional Superior Mesenteric Artery Syndrome Induced by an Optional IVC Filter

This patient suffered multiple injuries in a motor vehicle crash. She had an optional IVC filter placed in the usual fashion and location which resulted in a functional obstruction of the third part of the duodenum much as one would expect with a Superior Mesenteric Artery (SMA) syndrome. The symptoms persisted over the sixteen-day filter dwell time and resolved completely with the retrieval of the filter.

Randomized Controlled Study of an Absorbable Vena Cava Filter in a Porcine Model

PURPOSE

To compare the safety and efficacy of an absorbable inferior vena cava (IVC) filter and a benchmark IVC filter in a porcine model.

MATERIALS AND METHODS

A randomized controlled Good Laboratory Practice study was performed in Domestic Yorkshire cross swine. Sixteen swine were implanted with an absorbable IVC filter (test device; Adient Medical, Pearland, Texas); 8 were implanted with a benchmark metal IVC filter (control device; Cook Medical, Bloomington, Indiana). All animals underwent rotational digital subtraction pulmonary angiography and cavography (anteroposterior and lateral) before filter deployment and 5 and 32 weeks after deployment. Terminal procedures and necropsy were performed at 32 weeks. The IVC, heart, lungs, liver, and kidneys were harvested at necropsy. The reported randomized controlled GLP animal study was conducted at Synchrony Labs, Durham, North Carolina.

RESULTS

One animal died early in the test cohort of a recurring hemorrhage at the femoral access site resulting from a filter placement complication. All other animals remained clinically healthy throughout the study. No pulmonary embolism was detected at the 5- and 32-week follow-up visits. The absorbable filter subjects experienced less caval wall perforation (0% vs 100%) and thrombosis (0% vs 75%). The control device routinely perforated the IVC and occasionally produced collateral trauma to adjacent tissues (psoas muscle and aorta). The veins implanted with the absorbable filter were macroscopically indistinguishable from normal adjacent veins at 32 weeks except for the presence of radiopaque markers. Nontarget tissues showed no device-related changes.

CONCLUSIONS

Implantation of the absorbable IVC filter in swine proved safe with no pulmonary emboli detected. There was complete to near-complete resorption of the filter polymer by 32 weeks with restoration of the normal appearance and structure of the IVC.

Arteriovenous Fistula-A Rare Complication of IVC Filter Retrieval

Inferior vena cava (IVC) filters are important devices for patients who are at high risk for developing thrombi and pulmonary embolism but have conditions that preclude the use of pharmacologic anticoagulants. IVC filter retrieval has become an important quality initiative backed by Food and Drug Administration guidelines for prompt removal after the filter is no longer indicated. Filter retrieval is a common procedure that usually has very few complications. However, when the filter is tilted or embedded in the caval wall, advanced techniques of retrieval may be necessary. These techniques have a higher rate of success but also a higher risk of complications such as injury to the IVC. Here, we describe a case of IVC filter retrieval resulting in formation of an arteriovenous fistula between the right renal artery and IVC and subsequent successful repair of this fistula using a vascular plug.

Optimal Therapy for Unstable Pulmonary Embolism

There are no randomized controlled trials of thrombolytic therapy, pulmonary embolectomy, or inferior vena cava (IVC) filters in patients with unstable pulmonary embolism (those in shock or on ventilator support). Yet, there are many investigations of these treatments based on retrospective cohort studies using administrative data from large government and commercial databases. Extensive data from these cohort studies showed that thrombolytic therapy resulted in the lowest in-hospital all-cause mortality. The results of thrombolytic therapy were greatly improved if IVC filters were added. In fact, IVC filters decreased in-hospital all-cause mortality with anticoagulants alone or with pulmonary embolectomy as well as thrombolytic therapy in adults of all ages with unstable pulmonary embolism. The IVC filters reduced mortality only if inserted on the day of admission or the next day, while the patients were unstable and in a fragile condition. We conclude that the best treatment for patients with unstable pulmonary embolism is thrombolytic therapy combined with an IVC filter inserted during the period of fragility, while the patient is unstable, and this treatment is indicated in all unstable patients irrespective of age.

Thromboembolic diseases and the use of vena cava filters

Mr GW is a 77-year-old gentleman who is hoping to have a total knee replacement of his left knee. He underwent a knee replacement on the right in 2011 under spinal anaesthetic, where his postoperative period was complicated by a saddle pulmonary embolus (PE).

Vena cava filters in hospitalised patients with chronic obstructive pulmonary disease and pulmonary embolism

In view of the high case fatality rates of patients with chronic obstructive pulmonary disease (COPD) who have pulmonary embolism (PE) we speculated that such patients might benefit from vena cava filters. To test this hypothesis we assessed the database of the Nationwide Inpatient Sample. From 1998–2009, 440,370 patients were hospitalised with PE and COPD who were not in shock or ventilator-dependent and did not receive thrombolytic therapy or pulmonary embolectomy. In-hospital all-cause case fatality rate among those with filters was 5,890 of 68,800 (8.6%) (95% confidence interval [CI] = 8.4–8.8) compared with 38,960 of 371,570 (10.5%) (95% CI = 10.4–10.6) (p<0.0001) who did not receive filters. Case fatality rate was age-dependent. Only those who were older than aged 50 years had a lower in-hospital all-cause case fatality rate with filters. Among such patients, absolute risk reduction was 2.1% (95% CI = 1.9–2.3). The greatest reduction of case fatality rate with vena cava filters was shown in patients >aged 80 years, 11,720 of 81,600 (14.4%) compared with 1,570 of 17,220 (9.1%) (p<0.0001). In conclusion, a somewhat lower in-hospital all-cause case fatality rate was shown with vena filters in stable patients with PE >aged 50 years who also had COPD. The benefit was greatest in elderly patients. The benefit in terms of a decreased case fatality rate would seem to outweigh the risks of vena cava filters in such patients.

Safety and Efficacy of an Absorbable Filter in the Inferior Vena Cava to Prevent Pulmonary Embolism in Swine

Purpose To evaluate the immediate and long-term safety as well as thrombus-capturing efficacy for 5 weeks after implantation of an absorbable inferior vena cava (IVC) filter in a swine model. Materials and Methods This study was approved by the institutional animal care and use committee. Eleven absorbable IVC filters made from polydioxanone suture were deployed via a catheter in the IVC of 11 swine. Filters remained in situ for 2 weeks (n = 2), 5 weeks (n = 2), 12 weeks (n = 2), 24 weeks (n = 2), and 32 weeks (n = 3). Autologous thrombus was administered from below the filter in seven swine from 0 to 35 days after filter placement. Fluoroscopy and computed tomography follow-up was performed after filter deployment from weeks 1-6 (weekly), weeks 7-20 (biweekly), and weeks 21-32 (monthly). The infrarenal IVC, lungs, heart, liver, kidneys, and spleen were harvested at necropsy. Continuous variables were evaluated with a Student t test. Results There was no evidence of IVC thrombosis, device migration, caval penetration, or pulmonary embolism. Gross pathologic analysis showed gradual device resorption until 32 weeks after deployment. Histologic assessment demonstrated neointimal hyperplasia around the IVC filter within 2 weeks after IVC filter deployment with residual microscopic fragments of polydioxanone suture within the caval wall at 32 weeks. Each iatrogenic-administered thrombus was successfully captured by the filter until resorbed (range, 1-4 weeks). Conclusion An absorbable IVC filter can be safely deployed in swine and resorbs gradually over the 32-week testing period. The device is effective for the prevention of pulmonary embolism for at least 5 weeks after placement in swine. ^© RSNA, 2017.

Radiopaque Resorbable Inferior Vena Cava Filter Infused with Gold Nanoparticles

Failure to remove a retrievable inferior vena cava (IVC) filter can cause severe complications with high treatment costs. Polydioxanone (PPDO) has been shown to be a good candidate material for resorbable IVC filters. However, PPDO is radioluscent under conventional imaging modalities. Thus, the positioning and integrity of these PPDO filters cannot be monitored by computed tomography (CT) or x-ray. Here we report the development of radiopaque PPDO IVC filters based on gold nanoparticles (AuNPs). Commercially available PPDO sutures were infused with AuNPs. Scanning electron microscopy analysis confirmed the presence of AuNP on the surface of PPDO. Micro-CT and x-ray images of the AuNP-infused PPDO sutures showed significant signal enhancement compared to untreated PPDO sutures. Elemental analysis showed that gold loading exceeded 2000 ppm. Tensile strength and in vitro cytotoxicity showed no significant difference between AuNP-infused and untreated PPDO. In a 10-week stability study, neither the gold content nor the radiopacity of the infused PPDO sutures significantly changed in the first 6 weeks. The increased attenuation of AuNP-infused PPDO sutures indicates their major advantage as a radiopaque resorbable filter material, as the radiopacity allows monitoring of the position and integrity of the filter, thereby increasing its safety and efficacy.

Novel and Advanced Techniques for Complex IVC Filter Retrieval

OPINION STATEMENT

Inferior vena cava (IVC) filter placement is indicated for the treatment of venous thromboembolism (VTE) in patients with a contraindication to or a failure of anticoagulation. With the advent of retrievable IVC filters and their ease of placement, an increasing number of such filters are being inserted for prophylaxis in patients at high risk for VTE. Available data show that only a small number of these filters are retrieved within the recommended period, if at all, prompting the FDA to issue a statement on the need for their timely removal. With prolonged dwell times, advanced techniques may be needed for filter retrieval in up to 60% of the cases. In this article, we review standard and advanced IVC filter retrieval techniques including single-access, dual-access, and dissection techniques. Complicated filter retrievals carry a non-negligible risk for complications such as filter fragmentation and resultant embolization of filter components, venous pseudoaneurysms or stenoses, and breach of the integrity of the caval wall. Careful pre-retrieval assessment of IVC filter position, any significant degree of filter tilting or of hook, and/or strut epithelialization and caval wall penetration by filter components should be considered using dedicated cross-sectional imaging for procedural planning. In complex cases, the risk for retrieval complications should be carefully weighed against the risks of leaving the filter permanently indwelling. The decision to remove an embedded IVC filter using advanced techniques should be individualized to each patient and made with caution, based on the patient's age and existing comorbidities.

Severe tricuspid regurgitation due to valvular entrapment of an inferior vena cava stent

Endovascular venous stenting is increasingly performed for a variety of conditions. Inferior vena cava stent migration has been reported up to 6 months after placement; stent migration 6 months after implantation is uncommon. To our knowledge, this is only the second reported case of late stent migration with valve entrapment 1.

Optional Vena Cava Filters: What, Why, and When

Optional vena cava filters can used to provide either short-term or permanent protection from pulmonary embolism. These devices have recently become available for clinical use in the United States. However, there remains a paucity of data about these devices and their outcomes. This article reviews current and future devices, the rationale behind non-permanent caval filtration, and the generally accepted guidelines for their clinical application.

Retrievable Inferior Vena Cava Filters in Patients with Cancer: Complications and Retrieval Success Rate

Active cancer (ACa) is strongly associated with venous thromboembolism and bleeding. Retrievable inferior vena cava filters (RIVCF) are frequently placed in these patients when anticoagulation cannot be continued. Objectives. To describe the complications and retrieval rate of inferior vena cava filters in patients with ACa. Methods. Retrospective review of 251 consecutive patients with RIVCF in a single institution. Results. We included 251 patients with RIVCF with a mean age of 58.1 years and a median follow-up of 5.4 months (164 days, IQR: 34-385). Of these patients 32% had ACa. There were no differences in recurrence rate of DVT between patients with ACa and those without ACa (13% versus 17%, p = ns). Also, there were no differences in major filter complications (11% ACa versus 7% no ACa, p = ns). The filter retrieval was not different between groups (log-rank = 0.16). Retrieval rate at 6 months was 49% in ACa patients versus 64% in patients without ACa (p = ns). Filter retrieval was less frequent in ACa patients with metastatic disease (p < 0.01) or a nonsurgical indication for filter placement (p = 0.04). Conclusions. No differences were noted in retrieval rate, recurrent DVT, or filter complications between the two groups. ACa should not preclude the use of RIVCF.

Inferior vena cava filters: current best practices

Venous thromboembolism (VTE) is a common cause of inpatient and outpatient morbidity and mortality. While anticoagulant therapy is considered the primary means of prevention and treatment of VTE, inferior vena cava filters (IVCFs) are often used as an alternative or adjunct to anticoagulation. With the advent of retrievable filters indications have liberalized, to include placement for primary prophylaxis in high-risk patients. However, this practice is based on limited evidence supporting their efficacy in preventing clinically relevant outcomes. Since indiscriminate use of IVCFs can be associated with net patient harm and increased health care costs, knowledge of the literature surrounding IVCF utilization is critical for providers to adopt best practices. In this review, we will provide an overview of the literature as it relates to specific clinical questions that arise when considering IVCF utilization in the prevention and treatment of VTE. Practice-based recommendations will be reviewed to provide the clinician with guidance on challenging clinical scenarios.

Respiratory-Induced Haemodynamic Changes: A Contributing Factor to IVC Filter Penetration

PURPOSE

The purpose of the study is to evaluate the influence of respiratory-induced vena caval hemodynamic changes on filter migration/penetration.

MATERIALS AND METHODS

After placement of either a Gunther Tulip or Celect IVC filter, 101 consecutive patients scheduled for filter retrieval were prospectively enrolled in this study. Pre-retrieval CT scans were used to assess filter complications and to calculate cross-sectional area in three locations: at level of filter strut fixation, 3 cm above and 3 cm below. A 3D finite element simulation was constructed on these data and direct IVC pressure was recorded during filter retrieval. Cross-sectional areas and pressures of the vena cava were measured during neutral breathing and in Valsalva maneuver and identified filter complications were recorded. A statistical analysis of these variables was then performed.

RESULTS

During Valsalva maneuvers, a 60 % decrease of the IVC cross-sectional area and a fivefold increase in the IVC pressure were identified (p < 0.001). There was a statistically significant difference in the reduction of the cross-sectional area at the filter strut level (p < 0.001) in patient with filter penetration. Difficulty in filter retrieval was higher in penetrated or tilted filters (p < 0.001; p = 0.005). 3D computational models showed significant IVC deformation around the filter during Valsalva maneuver.

CONCLUSION

Caval morphology and hemodynamics are clearly affected by Valsalva maneuvers. A physiological reduction of IVC cross-sectional area is associated with higher risk of filter penetration, despite short dwell times. Physiologic data should be used to improve future filter designs to remain safely implanted over longer dwell times.

Case fatality rate with vena cava filters in hospitalized stable patients with cancer and pulmonary embolism

BACKGROUND

In view of the high risk of pulmonary embolism in patients with cancer, we tested the hypothesis that stable patients with pulmonary embolism who have cancer might be a subset of patients who would show a lower case fatality rate with vena cava filters than without filters.

METHODS

Stable patients with pulmonary embolism and cancer at discharge from short-stay hospitals throughout the US from 1998-2009 were identified from the Nationwide Inpatient Sample. Patients with pulmonary embolism who had a diagnostic code for shock, ventilatory support, thrombolytic therapy, or pulmonary embolectomy were excluded because such patients have been shown to have lower case fatality rate with filters.

RESULTS

In-hospital all-cause case fatality rate was lower with vena cava filters in stable patients with pulmonary embolism and solid malignant tumors providing they were aged >30 years, but there was variability according to type of tumor and age of patient. On average, case fatality rate among those >30 years with filters was 7070 of 69,350 (10.2%) (95% confidence interval, 10.0-10.4) versus 36,875 of 247,125 (14.9%) (95% confidence interval, 14.8-15.1) without filters (P <.0001) (relative risk 0.68). Among stable patients with hematological malignancies, case fatality rate, except in the elderly, was higher among those with vena cava filters than those without filters.

CONCLUSION

Stable patients with pulmonary embolism and solid malignant tumors who are older than age 30 years appear to be a subset of patients with pulmonary embolism who would benefit from vena cava filters, but this needs to be tested prospectively.

Chest pain from excluded inferior vena cava filter after stent placement

A 52-year-old patient presented with chronic substernal chest pain 18 months following exclusion of an inferior vena cava (IVC) filter with a self-expanding IVC stent. After a thorough work-up revealed no other possible cause of chest pain, the filter and stent were removed with subsequent resolution of chest pain. Intraoperatively, filter struts were found to have penetrated the posteromedial wall of the IVC and were abutting the periaortic neural plexus. Referred chest pain due to strut penetration of the caval wall is a novel complication of both IVC filters and IVC stents, demonstrating a need for continued surveillance.

Erosion of inferior vena caval filter noted during robotic assisted laparoscopic partial nephrectomy

Inferior Vena Cava (IVC) filters are mechanical devices implanted to provide prophylaxis against pulmonary emboli in patients for whom standard anticoagulation is either inadequate or contraindicated. A 67-year-old female with a 10-year-old indwelling IVC filter underwent robotic assisted laparoscopic partial nephrectomy for a right upper pole renal mass. Renal hilum dissection was complicated by adhesions secondary to eroded IVC filter struts. IVC filter erosion is a well-described phoenomena in both the radiologic and surgical literature. As many as 25% of filters are noted to be radiographically eroded; however, the incidence of clinically significant erosion is much less. Given the placement of endovascularly delivered IVC filters in close proximity to many urologic operative fields, it is important for urologists to be aware of the potential of eroded devices when pursuing para-caval dissections.

Care of patients with acute pulmonary emboli: a clinical review with cardiovascular focus

Acute pulmonary embolism (PE) is a common, multidisciplinary disease with substantial associated morbidity, mortality and healthcare expense. In this article we present a succinct review of diagnostic tools, risk stratification and medical therapies for cardiovascular care of patients with acute PE. While pulmonary angiography remains the 'gold standard' for diagnosis, a host of diagnostic modalities, interpreted in the setting of clinical probability, are available for patient assessment, including ECG, chest radiography, D-dimer, lower-extremity venous ultrasound, ventilation-perfusion scans, computed tomography and magnetic resonance angiography, and echocardiography, each with associated value. Diagnostic algorithms incorporate multiple tools in order to obtain a more comprehensive evaluation. Therapeutic anticoagulation remains the mainstay of therapy in PE. In massive PE, utilization of thrombolysis is reasonable in the absence of contraindications. Submassive PE, characterized by right ventricular dysfunction as assessed by echocardiography and ECG, is associated with higher mortality. Use of thrombolysis in submassive PE remains controversial. Catheter-directed therapies are emerging as an added approach to acute PE and have the potential to improve outcomes in PE. Use of inferior vena cava filters should be pursued in a select patient population as they serve to reduce recurrent acute PE; however, they are associated with more frequent deep venous thrombosis and provide no mortality benefit. In risk-stratified hemodynamically stable patients, an outpatient management strategy inclusive of therapeutic anticoagulation and careful clinical follow-up may be appropriate.

Impact of vena cava filters on in-hospital case fatality rate from pulmonary embolism

BACKGROUND

The effects of vena cava filters on case fatality rate are not clear, although they are used increasingly in patients with pulmonary embolism. The purpose of this investigation is to determine categories of patients with pulmonary embolism in whom vena cava filters reduce in-hospital case fatality rate.

METHODS

In-hospital all-cause case fatality rate according to the use of vena cava filters was determined in patients with pulmonary embolism discharged from short-stay hospitals throughout the United States using data from the Nationwide Inpatient Sample.

RESULTS

In-hospital case fatality rate was marginally lower in stable patients who received a vena cava filter: 21,420 of 297,700 (7.2%) versus 135,240 of 1,712,800 (7.9%) (P<.0001). Filters did not improve in-hospital case fatality rate if deep venous thrombosis was diagnosed in stable patients. A few stable patients (1.4%) received thrombolytic therapy. Such patients who received a vena cava filter had a lower case fatality rate than those who did not: 550 of 8550 (6.4%) versus 2950 of 19,050 (15%) (P<.0001). Unstable patients who received thrombolytic therapy had a lower in-hospital case fatality rate with vena cava filters than those who did not: 505 of 6630 (7.6%) versus 2600 of 14,760 (18%) (P<.0001). Unstable patients who did not receive thrombolytic therapy also had a lower in-hospital case fatality rate with a vena cava filter: 4260 of 12,850 (33%) versus 19,560 of 38,000 (51%) (P<.0001).

CONCLUSION

At present, it seems prudent to consider a vena cava filter in patients with pulmonary embolism who are receiving thrombolytic therapy and in unstable patients who may not be candidates for thrombolytic therapy. Future prospective study is warranted to better define in which patients a filter is appropriate.

Removal of retrievable vena cava filters in routine practice: a multicenter study

Vena cava filters (VCFs) are used to prevent pulmonary embolism when anticoagulation is contraindicated or in the event of progression of thrombosis despite adequate anticoagulation. Retrievable VCFs provide a potential advantage over permanent VCFs, but the appropriateness of their use and the frequency with which they are removed is not well established.

OBJECTIVES

Document the indications for insertion of retrievable VCFs, filter removal in hospital practice.

METHODS

Observational study conducted in three academic medical centers. Consecutive patients undergoing retrievable VCF insertion were identified. Clinical data was extracted from the patients' charts and follow up data were obtained from treating physicians after discharge.

RESULTS

300 patients were studied. The indication for filter insertion was acute bleeding (46.1%) or surgery (24.2%) in patients with acute thrombosis, prevention of venous thromboembolism in trauma (13.3%), potential bleeding in patients with deep vein thrombosis (9.1%) thromboembolism while on adequate anticoagulation (5.7%) and other (1.3%). 21 (7%) filters were removed. An unsuccessful attempt at retrieval was undertaken in a further 9 (3%) patients.

CONCLUSIONS

The use of retrievable VCFs was appropriate, with the possible exception of their prophylactic use in major trauma. The majority of VCFs were not removed, for reasons that are not apparent.

Vena cava interruption

Anticoagulation has been proven to be effective in preventing and treating deep vein thrombosis and pulmonary embolus. However, many critically ill patients are unable to receive anticoagulation or suffer recurrent venous thromboembolism despite adequate treatment. This article examines the use of vena cava filters in the critically ill. Indications for, techniques, and complications of vena cava filter insertion are reviewed. The importance of vena cava filters with the option to be retrieved and bedside insertion in the intensive care unit is emphasized.

Increasing use of vena cava filters for prevention of pulmonary embolism

PURPOSE

To test whether the use of vena cava filters continues to increase in the era of retrievable filters, suggesting that indications for insertion are broadening.

METHODS

Data from 1979 through 2006 are from the National Hospital Discharge Survey.

RESULTS

From 1979 through 1984, 17,000 vena cava filters were inserted; 8000 in patients with pulmonary embolism, 4000 in patients with deep venous thrombosis only, and 5000 in patients at risk of pulmonary embolism who had neither. From 1985 through 2006, 803,000 vena cava filters were inserted: 285,000 in patients with pulmonary embolism, 360,000 in patients with deep venous thrombosis only, and 158,000 in patients who had neither. The largest proportional increases in the use of vena cava filters since the introduction of retrievable filters was in patients at risk of pulmonary embolism but who had neither pulmonary embolism nor deep venous thrombosis. The trend toward increased use in this group began before retrievable filters were introduced. There was a 3-fold increase from 2001-2006.

CONCLUSION

Extensive use of permanent and retrievable vena cava filters in the US indicates liberalization of indications. It would seem that a more discriminate use of vena cava filters would be appropriate at the present time, keeping an open mind for broadened indications as data accrue.

Vena caval filters for the prevention of pulmonary embolism

BACKGROUND

Pulmonary emboli (PE) can have potentially fatal consequences. Inferior vena caval filters (VCFs) are metal alloy devices that mechanically trap fragmented thromboemboli from the deep leg veins en route to the pulmonary circulation. Filters are designed to be introduced (and in the case of retrievable filters, removed) percutaneously. Although their deployment seems of theoretical benefit, their clinical efficacy and adverse event profile is unclear.This is an update of a Cochrane review first published in 2007.

OBJECTIVES

To examine evidence for the effectiveness of VCFs in preventing pulmonary embolism (PE). Secondary outcomes were mortality, distal (to filter) thrombosis, and filter-related complications.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (last searched October 2009) and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library 2009, Issue 4 for randomised or controlled clinical trials of VCFs for the prevention of PE. The authors contacted filter manufacturers for information.

SELECTION CRITERIA

Controlled clinical trials (CCTs) and randomised controlled trials (RCTs) that examined the efficacy of filters in preventing PE.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted information.

MAIN RESULTS

Two studies were included involving a total of 529 people. One open quasi-randomised trial of 129 participants with traumatic hip fractures showed a reduction in PE but not mortality over a 34 day period in the filter group. The PREPIC (Prévention du Risque d'Embolie Pulmonaire par Interruption Cave) trial, was an open RCT of 400 participants with documented proximal deep vein thrombosis (DVT) or PE who received concurrent anticoagulation. Permanent VCFs prevented PE at eight years. No reduction in mortality was seen, but this reflected an older study population; the majority of deaths were due to cancer or cardiovascular causes. There was an increased incidence of (DVT) in the filter group. Adverse events were not reported.

AUTHORS' CONCLUSIONS

No recommendations can be drawn from the two studies. One study showed a reduction in PE rates but not mortality, but was subject to significant biases. The PREPIC study lacked statistical power to detect a reduction in PE over shorter and more clinically significant time periods. However, the trial demonstrated that permanent VCFs were associated with an increased risk of long term lower limb DVT.There is a paucity of VCFs outcome evidence when used within currently approved indications and a lack of trials on retrievable filters. Further trials are needed to assess vena caval filter safety and effectiveness.

Advanced treatment strategies for acute pulmonary embolism, including thrombolysis and embolectomy

The optimal treatment strategy for acute pulmonary embolism relies upon a multidisciplinary team that rapidly assesses available data, performs additional testing if necessary, weighs treatment options, and recommends an appropriate therapeutic plan to the patient and family. Round-the-clock availability is imperative. Centers that specialize in pulmonary embolism management offer a wide range of therapeutic options. Hospitals with more limited facilities should establish pulmonary embolism patient referral and transfer contingency plans that can be activated at a moment's notice. Management options include anticoagulation alone, thrombolysis plus anticoagulation, insertion of an inferior vena caval filter, catheter embolectomy, or surgical embolectomy. The decision-making process requires accurate risk stratification, which is comprised of several crucial components: clinical evaluation that includes history and physical examination, biomarker measurement especially of troponin, as well as assessment of right ventricular size and function based upon chest CT scanning and echocardiography. The 'old school' approach of declaring a benign prognosis based solely upon the presence of normal systemic arterial pressure can delay advanced therapy until after the onset of irreversible cardiogenic shock. We have now formulated a more contemporary, comprehensive, and multifaceted strategy to prognosticate. Our 'new approach' uses advanced treatment strategies in addition to anticoagulation for those pulmonary embolism patients deemed to be at high risk for a poor outcome.

Evaluation of wall motion and dynamic geometry of the inferior vena cava using intravascular ultrasound: implications for future device design

PURPOSE

To use intravascular ultrasound (IVUS) to define the wall motion of the inferior vena cava (IVC) during normal respiratory cycles and evaluate its dynamic geometry during Valsalva maneuvers.

METHODS

Between September 2005 and October 2006, 10 patients who were having IVC filters placed underwent IVUS prior to filter implantation. With the anesthetized patient in a supine position, a 10-second IVUS recording of IVC motion below the renal veins was made during both normal respiratory cycles and Valsalva maneuvers. Diameters (n = 100 measurements) were measured from the epicenter of the lumen in both a long and short axis. Changes in diameters were evaluated using a Student t test for paired data; variations in IVC wall motion circumference of the vessel were compared using an analysis of variance for repeated measurements. Intra-/interobserver variability was analyzed with Bland-Altman plots.

RESULTS

The mean IVC diameter was 14.3+/-4.1 mm in the short axis and 23.2+/-3.5 mm in the long axis. There was significant variation in infrarenal IVC wall movement about the circumference, with 1.4+/-0.2 mm (range 0.6-1.8) displacement in the short axis and 1.0+/-0.2 mm (range 0.2-1.4) displacement in the long axis during the normal respiratory cycle (p = 0.04). In the short axis, the IVC diameter significantly increased with Valsalva from 14.3+/-4.1 to 19.6+/-1.2 mm (p = 0.0001); in the long axis, the diameter increased from 23.2+/-3.5 to 24+/-1.2 mm (p = 0.02). With Valsalva, there was a significantly greater change in the short axis (30.9%+/-4.8%) compared to the long axis (3.4%+/-2.2%; p = 0.0001). There were no significant differences in the interobserver and intraobserver measurements.

CONCLUSION

In the supine position, the IVC is elliptical and deforms anisotropically during the normal respiratory cycle. The greatest displacement (36%) is in the short axis during a Valsalva maneuver. These profound changes within the venous system will require intracaval devices to have active fixation to prevent migration. Devices should be designed to accommodate these changes to prevent fatigue failure.

Pulmonary embolism--a state of the clot review

The assessment for pulmonary emboli is still Stone Age. History and physical findings are not sensitive or specific making it difficult to establish the diagnosis. PE is still potentially fatal. Death most often results from the severity of the clot, although delay in treatment may play a role. Clots, including deep venous thrombosis and pulmonary emboli, are the first disease that falls clearly under the Hospitalist specialty. An argument over what imaging is ideal continues to rage on, without any clear leader at this point. The CT scan and Ventilation/Perfusion scan are the two modalities being used most often. However without the use of a pretest probability the sensitivity and specificity can go down to less than 80%. The many new anticoagulants and oral therapies have widened the armamentarium, without increasing the success of therapy.

Etiology and VTE risk factor distribution in patients with inferior vena cava thrombosis

INTRODUCTION

Inferior vena cava (IVC) thrombosis is a rare event and data detailing the underlying etiology are scarce.

MATERIALS AND METHODS

Therefore, we reviewed all available cases of IVC thrombosis consecutively registered in the MAISTHRO (MAin-ISar-THROmbosis) database and described the prevalence of VTE risk factors and other conditions contributing to IVC thrombosis development.

RESULTS

53 patients (35 F, 18 M) with IVC thrombosis aged 12 to 79 years were identified. 40 patients (75.5%) developed thrombosis under the age of 45. Local problems, such as IVC anomalies or external venous compression, contributed to the development of thrombosis in 12 cases (22.6%). Lupus anticoagulants (10.9 vs. 2.3%, p=0.013) and malignoma (17.0 vs. 6.4%, p=0.023) were more prevalent in IVC thrombosis patients compared to 265 age and sex matched controls with isolated lower extremity DVT. No difference was identified with regard to inherited thrombophilia or other known VTE risk factors. Symptomatic pulmonary embolism (PE) occurred in 32.1% of IVC thrombosis patients compared to 15.2% of controls (p=0.005).

CONCLUSIONS

Local problems such as IVC anomalies and external venous compression, malignancy and the presence of lupus anticoagulants contribute to the risk of IVC thrombosis. The risk of symptomatic pulmonary embolism in the acute setting is high.

Form And Function Of Vena Cava Filters: How Do Optional Filters Measure Up?

The function of vena cava filters, preventing pulmonary embolism while maintaining caval patency, is associated with the design. Several characteristics have been reported. This report evaluates retrievable filter designs in comparison with previously marketed designs with respect to efficacy and safety. Three inferior vena cava (IVC) filters (Gunther Tulip, Bard Recovery, and the Cordis OptEase) were compared on the basis of design characteristics associated with function, shape, number of trapping levels, and fixation. Adverse events reported in the literature and to the US Food and Drug Administration Manufacturers and User Facility Device Experience Database (MAUDE) were summarized. The major differences among device types include the fixation, the volume and number of trapping levels, and the amount of metal in the IVC. The MAUDE registry reported adverse events that had been hypothesized from the analysis of in vitro and in vivo testing. The Recovery and OptEase filters had the highest number of clinically important reports. From 12 to 57% were retrieved between 3 days and 11 months. Adaptations made to facilitate retrieval led to unacceptable sequelae. The small number removed, the length of time they are left in place, and the risks associated with retrieval suggest that optional filters may not be equivalent to approved permanent devices.

A prospective long-term study of 220 patients with a retrievable vena cava filter for secondary prevention of venous thromboembolism

BACKGROUND

The immediate and long-term clinical events associated with the placement and removal of a retrievable filter (ALN filter; ALN Implants Chirurgicaux; Ghisonaccia, France) remain largely unknown.

METHODS

This was a prospective cohort study with an 18-month follow-up. All consecutive patients scheduled for placement of an ALN filter between April 1999 and June 2005 in the Radiology Department of our hospital were included.

RESULTS

During the study period, placement of an ALN filter was indicated in 220 patients (mean age, 70.8 years), who were followed up for a median duration of 338.5 days (range, 1 to 561 days); 148 patients (67.3%) completed the 18-month follow-up. No patients were unavailable for follow-up. All patients had an acute or past venous thromboembolism. Main indications were recurrent venous thromboembolism despite adequate anticoagulation therapy (10.9%), transient bleeding event (21.8%), definitive contraindication for anticoagulant therapy (26.8%), or obligation to stop anticoagulant therapy due to major surgery, major trauma, or invasive procedure (37.7%). Filter insertion was successful in 98.6% of patients and resulted in an immediate complication in 11.8%. The median duration of filter implantation was 166 days (first to third quartiles, 34 to 478 days). Meanwhile, 17.0% (37 of 217 patients) had at least one venous thromboembolic event. Filter retrieval was attempted in 25.3% of patients after a median of 51 days (range, 6 to 352 days); removal was successful at the first attempt in 92.7% of patients.

CONCLUSIONS

The filter could be easily inserted and successfully removed up to 1 year after insertion. Its safety and efficacy in preventing pulmonary embolism should be properly assessed in a randomized study.

The use of intravascular ultrasound imaging to improve use of inferior vena cava filters in a high-risk bariatric population

OBJECTIVE

Pulmonary embolism is the leading cause of death after gastric bypass procedures for obesity, approximating 0.5% to 4%. All bariatric patients, but especially the super-obese, which have a body mass index (BMI) >50 kg/m(2), are at significant risk for postoperative venous thromboembolism (VTE). Visualization and weight limitations of fluoroscopy tables exclude most bariatric and all super-obese patients from inferior vena cava (IVC) filter placement using fluoroscopy. Intravascular ultrasound (IVUS)-guided IVC filter placement is the only modality that allows these high-risk patients to have an IVC filter placed.

METHODS

Hospital and outpatient records of the 494 patients who underwent gastric bypass procedures from January 1, 2004, to May 31, 2006, were reviewed. All patients who had concurrent IVC filter placement with the use of IVUS guidance were selected. Comorbidities, outcomes, and complications were recorded.

RESULTS

We identified 27 patients with mean BMI of 70 +/- 3 kg/m(2); of these, 25 were super-obese (BMI >50 kg/m(2)). Procedures included five laparoscopic and 22 open gastric bypass operations. All patients underwent concurrent IVC filter placement using IVUS guidance. In addition to super-obesity, indications for IVC filter placement included history of VTE (n = 4), known hypercoagulable state (n = 2), and profound immobility (n = 21). Mean follow up was 293 +/- 40 days. Technical success rate was 96.3%. There were no catheter site complications. In one surviving patient, a nonfatal pulmonary embolism was detected by computed tomography 2 months postoperatively. Two patients died, and autopsy excluded VTE as the cause of death in both.

CONCLUSION

This study suggests efficacy of IVUS-guided IVC filter placement in preventing mortality from pulmonary embolism in high-risk bariatric patients, including the super-obese. IVUS-guided IVC filter placement can be safely performed with an excellent success rate in all bariatric patients, including the super-obese, who otherwise would not be candidates for IVC filter placement due to the limitations imposed by their large body habitus.