Perforation of the IVC: Rule Rather Than Exception After Longer Indwelling Times for the Günther Tulip and Celect Retrievable Filters

Experimental Study on Penetration of Smaller Inferior Vena Cava after Conical Filter Placement: Results in a Swine Model

OBJECTIVES

Inferior vena cava (IVC) penetration is a prevalent complication following the placement of conical filters. However, there is a paucity of studies examining the penetration in smaller IVC. The objective of this study was to assess the time of penetration, the incidence of serious complications associated with penetration, and the process of IVC wall repair in the smaller IVC following the placement of a conical filter.

METHODS

Twenty pigs were randomly assigned to 2 groups and received either Celect or Denali filters. Weekly follow-up imaging using computed tomography venography (CTV) of the IVC was conducted to monitor the position of the IVC filter struts until at least 1 strut was observed to be penetrating the vessel wall. At necropsy, a comprehensive gross and histological examination was performed on the IVC and adjacent anatomical structures in all animals.

RESULTS

The puncture and cavography procedures were successfully conducted on all animals, and no significant differences were found in the mean diameter of the IVC between the Celect and Denali groups (15.89 ± 1.27 mm vs. 16.39 ± 1.39 mm, P > 0.05). All filters were implanted without complications. CTV detected IVC penetration within 9 weeks, which was confirmed during necropsy. The Celect group had a significantly earlier time of IVC penetration compared to the Denali group (2.43 ± 0.52 weeks vs. 6.81 ± 1.32 weeks, P ＜ 0.001). No evidence of filter tilt, fracture, migration, caval thromboses, retroperitoneal bleeding, wall hematoma, tearing of the IVC wall, or peripheral tissue and organ damage was observed during the CTV and subsequent necropsy. Additionally, histological analysis showed that the Celect group had a lower percentage area of collagen fiber compared to the Denali group (33.92% vs. 49.04%, P ＜ 0.001). The fiber proliferation was positively correlated linearly with the indwelling time of filter (r = 0.97, P ＜ 0.001).

CONCLUSIONS

Penetration can occur within a relatively brief period following the placement of the conical filter into the smaller IVC. Nevertheless, no short-term severe complications were observed in connection with the penetration. The proliferation of fibers in the IVC wall exhibited a positive linear correlation with the duration of filter indwelling.

Evolving Landscape of Inferior Vena Cava Filter Utilization: A Comprehensive Bibliometric Analysis

This bibliometric analysis scrutinizes the evolution and current challenges in the use of Inferior Vena Cava (IVC) filters, focusing on trends from 2004 to 2023. Analyzing 2470 records, we report the United States' dominant role, with over half of the studies, and a significant shift towards retrievable filters. Despite technological advancements, controversies persist regarding efficacy, safety, and retrieval issues. Our findings point to the need for refined clinical guidelines and enhanced management strategies to navigate the complex landscape of IVC filter utilization effectively.

Comparison of success and cost after retrieval of two inferior vena cava filters

OBJECTIVE

The objective of this study was to help guide inferior vena cava (IVC) filter choices by better understanding the retrieval characteristics, complications, and total costs between two commonly used IVC filters.

METHODS

All patients who underwent retrieval or attempted retrieval of Denali (Bard Peripheral Vascular) or Option (Argon Medical Devices) IVC filters were identified between March 2016 and October 2021 at a single tertiary care center. Those with imaging studies that permitted evaluation of filter placement, presence or degree of tilt, and/or hooking of the filter into the IVC wall were included in the present study. Filter retrieval success, number of attempts, use of advanced techniques, and fluoroscopy and procedural times were recorded and compared between the two filters.

RESULTS

A total of 87 patients presented for retrieval of 52 Denali and 35 Option Elite filters during the study period. Denali filters were more likely to be successfully retrieved at the first attempt (94% vs 77%; P = .019). The procedural and fluoroscopy times were shorter for Denali filters (29 minutes vs 63 minutes [P < .001] and 7 minutes vs 25 minutes [P < .001], respectively). Denali filters were less likely to be significantly tilted (≥15○) at retrieval (12% vs 29%; P < .001) or to have the filter hook embedded in the IVC wall (6% vs 40%; P < .001). Tilting of the filter of ≥15○ had no significant effects on the retrieval success rate (no tilt or tilt <15○ vs tilt of ≥15○: 98% vs 100%; P = .58). In contrast, filter hook penetration into the IVC wall significantly reduced successful recovery (41% vs 99%; P < .001).

CONCLUSIONS

The findings from this study suggest that although the filter designs are similar, a benefit exists in the ease of retrievability of the Denali over the Option filter. We found that tilting and hooking of the filter in the IVC wall occurred significantly more with the Option filter. These factors likely made retrieval more difficult and contributed to the longer procedure and fluoroscopy times.

Inferior Vena Cava Filter Retrieval: Simple to Complex

Retrievable inferior vena cava filters were designed to provide mechanical prophylaxis from pulmonary embolism with the intent for retrieval once no longer indicated, and have been utilized at a high rate since their introduction. Unfortunately, retrieval rates have historically lagged behind, in part due to significant rates of failed standard retrieval techniques for filters with prolonged dwell time. Refinement in advanced retrieval techniques has now allowed (in experienced centers) for safe removal of filters previously considered irretrievable. An individualized approach is necessary for each potential advanced filter retrieval to determine appropriate course of action. This review will emphasize complex filter retrieval techniques amidst a larger discussion of inferior vena cava filters and their management.

Difficult withdrawal of an inferior vena cava filter: Technical considerations and associated variables

OBJECTIVE

To analyse the efficacy of the procedure for withdrawing an inferior vena cava (IVC) filter and the clinical and radiological factors associated with difficult withdrawal.

MATERIAL AND METHODS

This retrospective observational study included patients who underwent IVC filter withdrawal at a single centre between May 2015 and May 2021. We recorded demographic, clinical, procedural, and radiological variables: type of IVC filter, angle with the IVC > 15°, hook against the wall, and legs embedded in the IVC wall > 3 mm. The efficacy variables were fluoroscopy time, success of IVC filter withdrawal, and number of attempts to withdraw the filter. The safety variables were complications, surgical removal, and mortality. The main variable was difficult withdrawal, defined as more than 5 min fluoroscopy or more than 1 attempt at withdrawal.

RESULTS

A total of 109 patients were included; withdrawal was considered difficult in 54 (49.5%). Three radiological variables were more common in the difficult withdrawal group: hook against the wall (33.3% vs. 9.1%; p = 0.027), embedded legs (20.4% vs. 3.6%; p = 0.008), and >45 days since IVC filter placement (51.9% vs. 25.5%; p = 0.006). These variables remained significant in the subgroup of patients with OptEase IVC filters; however, in the group of patients with Celect IVC filters, only the inclination of the IVC filter >15 ° was significantly associated with difficult withdrawal (25% vs 0%; p = 0.029).

CONCLUSION

Difficult withdrawal was associated with time from IVC placement, embedded legs, and contact between the hook and the wall. The analysis of the subgroups of patients with different types of IVC filters found that these variables remained significant in those with OptEase filters; however, in those with cone-shaped devices (Celect), the inclination of the IVC filter >15° was significantly associated with difficult withdrawal.

Conservative Management of Duodenal Penetration by Inferior Vena Cava Filter: Case Report and Review

Duodenal penetration is a late complication associated with the placement of inferior vena cava (IVC) filters. In this case report, we are presenting a case of asymptomatic duodenal penetration by IVC filter that was managed conservatively.

Removal of inferior vena cava filter by open surgery after failure of endovenous retrieval

Background

The permanent placement of inferior vena cava (IVC) filters may lead to numerous complications and their removal is recommended once the risk of pulmonary embolism is reduced. Removal of IVC filters by endovenous means is preferred. But failure of endovenous removal happens when recycling hooks penetrate the vein wall and filters are left in place for too long time. In these scenarios, open surgery may be effective for removal of IVC filters. We aimed to describe the surgical approach, outcomes, and 6-month follow-up of the removal of IVC filter by open surgery, after the failure of removal via the endovenous method.

Methods

A total of 1,285 patients with retrievable IVC filters were admitted from July 2019 to June 2021, including 1,176 (91.5%) endovenous filter removals, and 24 (1.9%) open surgical IVC filter removals after the failure by endovenous method, of whom 21 (1.6%) were followed-up and eligible for analysis of the study. Patient characteristics, filter type, filter removal rate, IVC patency rate, and complications were retrospectively analyzed.

Results

Twenty-one patients were left with IVC filters for 26 (10, 37) months, of which 17 (81.0%) patients had non-conical filters and 4 (19.0%) had conical filters; all 21 filters were successfully removed, with a 100% removal rate, no deaths, no serious complications, and no symptomatic pulmonary embolism. At the 3rd month follow-up after surgery and 3rd month follow-up after discontinuation of anticoagulation therapy, only 1 case (4.8%) had IVC occlusion, but without any occurrence of new lower limb deep venous thrombosis and silent pulmonary embolism.

Conclusion

Open surgery can be used for the removal of IVC filters after failure of removal by endovenous method or when accompanied by complications without symptoms of pulmonary embolism. Open surgical approach can be used as an adjunctive clinical intervention for the removal of such filters.

Design and Haemodynamic Analysis of a Novel Anchoring System for Central Venous Pressure Measurement

BACKGROUND/OBJECTIVE

In recent years, treatment of heart failure patients has proved to benefit from implantation of pressure sensors in the pulmonary artery (PA). While longitudinal measurement of PA pressure profoundly improves a clinician's ability to manage HF, the full potential of central venous pressure as a clinical tool has yet to be unlocked. Central venous pressure serves as a surrogate for the right atrial pressure, and thus could potentially predict a wider range of heart failure conditions. However, it is unclear if current sensor anchoring methods, designed for the PA, are suitable to hold pressure sensors safely in the inferior vena cava. The purpose of this study was to design an anchoring system for accurate apposition in inferior vena cava and evaluate whether it is a potential site for central venous pressure measurement.

MATERIALS AND METHODS

A location inferior to the renal veins was selected as an optimal site based on a CT scan analysis. Three anchor designs, a 10-strut anchor, and 5-struts with and without loops, were tested on a custom-made silicone bench model of Vena Cava targeting the infra-renal vena cava. The model was connected to a pulsatile pump system and a heated water bath that constituted an in-vitro simulation unit. Delivery of the inferior vena cava implant was accomplished using a preloaded introducer and a dilator as a push rod to deploy the device at the target area. The anchors were subjected to manual compression tests to evaluate their stability against dislodgement. Computational Fluid Dynamics (CFD) analysis was completed to characterize blood flow in the anchor's environment using pressure-based transient solver. Any potential recirculation zones or disturbances in the blood flow caused by the struts were identified.

RESULTS

We demonstrated successful anchorage and deployment of the 10-strut anchor in the Vena Cava bench model. The 10-strut anchor remained stable during several compression attempts as compared with the other two 5-strut anchor designs. The 10-strut design provided the maximum number of contact points with the vessel in a circular layout and was less susceptible to movement or dislodgement during compression tests. Furthermore, the CFD simulation provided haemodynamic analysis of the optimum 10-strut anchor design.

CONCLUSIONS

This study successfully demonstrated the design and deployment of an inferior vena cava anchoring system in a bench test model. The 10-strut anchor is an optimal design as compared with the two other 5-strut designs; however, substantial in-vivo experiments are required to validate the safety and accuracy of such implants. The CFD simulation enabled better understanding of the haemodynamic parameters and any disturbances in the blood flow due to the presence of the anchor. The ability to place a sensor technology in the vena cava could provide a simple and minimally invasive approach for heart failure patients.

Application of Deep Learning to IVC Filter Detection from CT Scans

IVC filters (IVCF) perform an important function in select patients that have venous blood clots. However, they are usually intended to be temporary, and significant delay in removal can have negative health consequences for the patient. Currently, all Interventional Radiology (IR) practices are tasked with tracking patients in whom IVCF are placed. Due to their small size and location deep within the abdomen it is common for patients to forget that they have an IVCF. Therefore, there is a significant delay for a new healthcare provider to become aware of the presence of a filter. Patients may have an abdominopelvic CT scan for many reasons and, fortunately, IVCF are clearly visible on these scans. In this research a deep learning model capable of segmenting IVCF from CT scan slices along the axial plane is developed. The model achieved a Dice score of 0.82 for training over 372 CT scan slices. The segmentation model is then integrated with a prediction algorithm capable of flagging an entire CT scan as having IVCF. The prediction algorithm utilizing the segmentation model achieved a 92.22% accuracy at detecting IVCF in the scans.

Pathological Analysis and Clinical Evolution After Radiological Removal of Retrievable Vena Cava Filters

Objective

Retrievable inferior vena cava filters (IVCF) have been developed because permanent filters have been associated with an increased risk of recurrent deep venous thrombosis. There is no data on the interactions of IVCF with the inferior vena cava (intrafilter thrombi, insertion through the venous wall) even though this may alter the course after retrieval of the IVCF.

Methods

A review of 85 consecutive patients undergoing retrieval of IVCF placed at a single center was performed from January 1, 2010 and December 31, 2014. Inferior vena cava filter were examined for presence of intrafilter thrombus at time of retrieval. Filter position and presence of intraluminal thrombus were examined. Patient outcomes, including recurrence of deep vein thrombosis (DVT) and death, were captured at 3 month followup.

Results

Eighty five patients were identified, with intrafilter thrombi found in 69 (81%) patients and venous wall fragments found in 75 (88%) patients. However, their presence was not associated with an increased risk of recurrent venous thromboembolism (VTE) or death during follow up.

Conclusions

Intrafilter thrombi and venous wall fragments are frequently found in removed IVCF but are not associated with a worse prognosis. They may not modify the therapeutic management of patients.

Role of Physical Therapists in the Management of Individuals at Risk for or Diagnosed With Venous Thromboembolism: Evidence-Based Clinical Practice Guideline 2022

No matter the practice setting, physical therapists work with patients who are at risk for or who have a history of venous thromboembolism (VTE). In 2016, the first clinical practice guideline (CPG) addressing the physical therapist management of VTE was published with support by the American Physical Therapy Association's Academy of Cardiovascular and Pulmonary Physical Therapy and Academy of Acute Care, with a primary focus on lower extremity deep vein thrombosis (DVT). This CPG is an update of the 2016 CPG and contains the most current evidence available for the management of patients with lower extremity DVT and new key action statements (KAS), including guidance on upper extremity DVT, pulmonary embolism, and special populations. This document will guide physical therapist practice in the prevention of and screening for VTE and in the management of patients who are at risk for or who have been diagnosed with VTE. Through a systematic review of published studies and a structured appraisal process, KAS were written to guide the physical therapist. The evidence supporting each action was rated, and the strength of statement was determined. Clinical practice algorithms based on the KAS were developed that can assist with clinical decision-making. Physical therapists, along with other members of the health care team, should implement these KAS to decrease the incidence of VTE, improve the diagnosis and acute management of VTE, and reduce the long-term complications of VTE.

What happens after they survive? The role of anticoagulants and antiplatelets in IVC injuries

Background

Venous thromboembolism (VTE) after an inferior vena cava (IVC) injury is a devastating complication. Current practice involves variable use of anticoagulation and antiplatelet (AC/AP) agents. We hypothesized that AC/AP can reduce the incidence of VTE and that delayed institution of AC/AP is associated with increased VTE events.

Methods

We retrospectively reviewed IVC injuries cared for at a large urban adult academic level 1 trauma center between January 1, 2008 and December 31, 2020, surviving 72 hours. Patient demographics, injury mechanism, surgical repair, type and timing of AC, and type and timing of VTE events were characterized. Postoperative AC status during hospital course before an acute VTE event was delineated by grouping patients into four categories: full, prophylactic, prophylactic with concomitant AP, and none. The primary outcome was the incidence of an acute VTE event. IVC ligation was excluded from analysis.

Results

Of the 76 patients sustaining an IVC injury, 26 were included. The incidence of a new deep vein thrombosis distal to the IVC injury and a new pulmonary embolism was 31% and 15%, respectively. The median onset of VTE was 5 days (IQR 1–11). Four received full AC, 10 received prophylactic AC with concomitant AP, 8 received prophylactic AC, and 4 received no AC/AP. New VTE events occurred in 0.0% of full, in 30.0% of prophylactic with concomitant AP, in 50.0% of prophylactic, and in 50.0% without AC/AP. There was no difference in baseline demographics, injury mechanisms, surgical interventions, and bleeding complications.

Discussion

This is the first study to suggest that delay and degree of antithrombotic initiation in an IVC-injured patient may be associated with an increase in VTE events. Consideration of therapy initiation should be performed on hemostatic stabilization. Future studies are necessary to characterize the optimal dosing and temporal timing of these therapies.

Level of evidence

Therapeutic, level 3.

Vena Cava Filters: Toward Optimal Strategies for Filter Retrieval and Patients' Follow-Up

Mortality rates associated with venous thromboembolism (VTE) are high. Inferior vena cava filters (IVCFs) have been frequently placed for these patients as part of their treatment, albeit the paucity of data showing their ultimate efficacy and potential risk of complications. Issues regarding long-term filter dwell time are accounted for in society guidelines. This topic has led to an FDA mandate for filter retrieved as soon as protection from pulmonary embolism is no longer needed. However, even though most are retrievable, some were inadvertently left as permanent, which carries an incremental lifetime risk to the patient. In the past decade, attempts have aimed to determine the optimal time interval during which filter needs to be removed. In addition, distinct strategies have been implemented to boost retrieval rates. This review discusses current conflicts in indications, the not uncommon complications, the rationale and need for timely retrieval, and different quality improvement strategies to fulfill this aim.

Clinical outcomes of retrievable inferior vena cava filters for venous thromboembolic diseases

Aim: To identify literature evidence assessing retrievable inferior vena cava filter (rIVCF) for venous thromboembolic diseases. Methods: A systematic literature search was conducted to identify relevant references from the mainstay English and Chinese bibliographic databases (search period: January 2003 to October 2019). Results: 80 original studies with 11,413 patients were included in this review. The success rates of deploying the six types of rIVCFs ranged from 98.4 to 100.0%. Denali had the highest retrieval success rate (95.4-97.6%). The incidence rates of fracture and perforation associated with retrieving the six rIVCFs were less than 2%. Conclusion: The approved rIVCF had comparable clinical profiles, except that Denali was easier to be retrieved than other rIVCF.

Hazardous Situation During Conversion of a Long-term Indwelling VenaTech Convertible Inferior Vena Cava Filter

BACKGROUND

A lack of high-quality research and data has restricted the comprehensive understanding of the conversion procedure of convertible inferior vena cava filters. The aim of this study was to present an unusual situation with a high risk of causing complication, during conversion of VenaTech convertible inferior vena cava filter and our management procedure.

METHODS

Lower extremity deep venous thrombi were detected in a 62-year-old woman before major orthopedic surgery. A VenaTech convertible inferior vena cava filter was placed to prevent possible pulmonary embolism and 106 days later, the filter was converted without any complications.

RESULTS

At the 6-month follow-up, no adverse events were reported.

CONCLUSIONS

The long-term indwelling of a filter might increase the complexity and uncertainty of the conversion procedure. This report presented a rare but hazardous situation during conversion and our management procedure.

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. .

Prevalence and Characterization of Interaction of Retrievable Inferior Vena Cava Filters with the Spine in Patients Undergoing Complex Filter Removal

PURPOSE

To examine spinal interaction types and prevalence of inferior vena cava (IVC) filters in patients presenting for complex filter removal.

MATERIALS AND METHODS

The records of 447 patients presenting for complex removal of IVC filters were reviewed, including patient demographics, IVC filter dwell time, filter fracture status, and computed tomography (CT) evidence of filter interaction with the spine. Spinal interaction was defined as a filter strut touching or penetrating into the vertebral body or disc. Patients with evidence of filter penetration and spinal interaction had abdominal CT that preceded filter removal assessed by 2 interventional radiologists to categorize the type of spinal interaction, including bony reaction and osteophyte formation.

RESULTS

CT evidence of spinal interaction by the filter was found in 18% of patients (80/447). Interaction with the spine was more common in single point of fixation filters than filters with rails (P = .007) and was more likely in filters with round wires than flat wires (P = .0007). Patients with interaction had longer dwell times (mean [SD] 5.7 [4.46] y) compared with patients without interaction (mean [SD] 3.2 [3.85] y); this relationship was significant (P < .0001). Women were more likely than men to experience filter/spine interaction (P = .04). Filters with spinal interaction were more likely to be fractured (P = .001). Filter interaction was found in 38% (30/78) of patients with symptoms, including chest and back pain, compared with 14% (50/369) of patients without symptoms (P < .0001, odds ratio 3.99).

CONCLUSIONS

Retrievable IVC filters may interact with the spine. These interactions are associated with longer filter dwell times, female sex, and round wire filter construction.

Changes in inferior vena cava filter placement and retrieval practice patterns from a population health perspective

PURPOSE

Inferior vena cava (IVC) filters are placed to reduce venous thromboembolism (VTE)-related morbidity and mortality, though the evidence supporting this practice is limited. In 2010, the Food and Drug Administration (FDA) released a device safety advisory due to the risk of filter migration, fracture, and thrombosis with long-term use. The purpose of this study was to evaluate trends and predictors for IVCF placement and retrieval over a 10-year time period from a population health perspective.

MATERIALS AND METHODS

De-identified patient information from the State Inpatient Databases (SID) and the States Ambulatory Surgery and Services Databases (SASD) for Florida and California were used to identify all patients who underwent IVC filter placement from 2005 to 2014 and 2005 to 2011, respectively. Hospital practice patterns were assessed as a function of time as well as IVC filter placement and retrieval volume. Temporal trends were evaluated for statistical significance using the Cochran-Armitage test.

RESULTS

A total of 181,260 IVC filters were placed in 178,327 patients over the study period. IVC filter placements peaked in 2010; following the FDA advisory in 2010, however, IVC filter placements monotonically decreased each subsequent year. The proportion of IVCF placement patients with both acute DVT and PE (17.6% vs 11.8%, P < 0.001) at the time of hospitalization increased; likewise, the proportion of IVCF patients with acute DVT or PE with a concomitant acute contraindication to anticoagulation at the time of hospitalization increased as well following 2010 (17.0% vs 11.9%, P < 0.001). From 2005 to 2014, there was a continual increase in both filter retrieval procedures as well overall percentage of filters retrieved. However, estimated retrieval rates remained low, with a retrieval rate of less than 6% in 2014.

CONCLUSION

Following the FDA warning in 2010, there was a significant decrease in IVC filter placements, with filter placements more frequently performed in patients with poorer health. While retrieval rates increased over time, they remained low.

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.

Radiologists' Field Guide to Retrievable and Convertible Inferior Vena Cava Filters

OBJECTIVE. Inferior vena cava (IVC) filters are commonly used in patients who are at risk for life-threatening pulmonary embolism. After the introduction of permanent devices, numerous retrievable and convertible designs became available. Inaccurate identification can lead to confusion in options for filter retrieval and anticoagulation. CONCLUSION. This article highlights device designs of retrievable and convertible IVC filters to assist interpretation of diagnostic studies.

The Clinical Rationale for the Sentry Bioconvertible Inferior Vena Cava Filter for the Prevention of Pulmonary Embolism

The Sentry inferior vena cava (IVC) filter is designed to provide temporary protection against pulmonary embolism (PE) during transient high-risk periods and then to bioconvert after 60 days after implantation. At the time of bioconversion, the device's nitinol arms retract from the filtering position into the caval wall. Subsequently, the stable stent-like nitinol frame is endothelialized. The Sentry bioconvertible IVC filter has been evaluated in a multicenter investigational-device-exemption pivotal trial (NCT01975090) of 129 patients with documented deep vein thrombosis (DVT) or PE, or at temporary risk of developing DVT or PE, and with contraindications to anticoagulation. Successful filter conversion was observed in 95.7% of patients at 6 months (110/115) and 96.4% at 12 months (106/110). Through 12 months, there were no cases of symptomatic PE. The rationale for development of the Sentry bioconvertible device includes the following considerations: (1) the period of highest risk of PE for the vast majority of patients occurs within the first 60 days after an index event, with most of the PEs occurring in the first 30 days; (2) the design of retrievable IVC filters to support their removal after a transitory high-PE-risk period has, in practice, been associated with insecure filter dynamics and time-dependent complications including tilting, fracture, embolization, migration, and IVC perforation; (3) most retrievable IVC filters are placed for temporary protection, but for a variety of reasons they are not removed in any more than half of implanted patients, and when removal is attempted, the procedure is not always successful even with advanced techniques; and (4) analysis of Medicare hospital data suggests that payment for the retrieval procedure does not routinely compensate for expense. The Sentry device is not intended for removal after bioconversion. In initial clinical use, complications have been limited. Long-term results for the Sentry bioconvertible IVC filter are anticipated soon.

Long-term computed tomography follow-up results of strut penetration of inferior vena cava filters

OBJECTIVE

This study aimed to investigate the incidence of inferior vena cava (IVC) filter strut penetration and risk factors of organ involvement.

METHODS

From June 2003 to August 2015, there were 138 patients with deep venous thrombosis who received an IVC filter. Among 104 patients who did not have the IVC filter retrieved, 66 had follow-up computed tomography and were included in this study. The IVC filters used were 21 Günther Tulip (Cook Medical, Bloomington, Ind), 26 Celect (Cook Medical), and 19 OptEase (Cordis Corp, Bridgewater, NJ) filters. Filter strut penetration was categorized by a previously published scale of grade 0 to grade 3, and organ involvement was specifically assessed. Multivariate analysis was used to identify risk factors for organ-involving strut penetration (grade 3).

RESULTS

The median age of the patients was 66 years (27-84 years), and 46% were male. Median computed tomography follow-up duration was 14 months (1-137 months). IVC strut penetration was detected in all patients. Grade 1, grade 2, and grade 3 were 29%, 36%, and 35%, respectively. The risk factor of grade 3 penetration was indwelling time ≥30 months on binary logistic regression analysis (odds ratio, 4.395; 95% confidence interval, 1.179-16.385; P = .027).

CONCLUSIONS

Regardless of type of IVC filter, the incidence of strut penetration was high. The risk of adjacent organ involvement increases over time. Retrievable IVC filters need close follow-up and retrieval as soon as they are no longer needed.

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.

Design and evaluation of a novel biodegradable inferior vena cava filter

Inferior vena cava filter has been increasingly applied in clinical practice to prevent pulmonary embolism. Nowadays, various complications after implanting conventional filters seriously hinder clinical applications. Therefore, in this paper, a novel biodegradable inferior vena cava filter was designed based on biodegradable materials, which is an hourglass-like filter anchored inside a stent structure fixed by connecting fibers. Firstly, mechanical tests in crimp were performed to study the expansion properties of the filter, showing that the biodegradable inferior vena cava filter could achieve self-expansion easily. Furthermore, the biodegradable inferior vena cava filters and fibers were incubated in phosphate buffer media (pH = 7.4 ± 0.2) at 37°C for six months. Scanning electron microscope micrograph showed that the stents exhibited no significant dimensional and structural changes and had enough radial force to support the vessel. During the degradation period, the results of scanning electron microscope, gel permeation chromatography, differential scanning calorimetry and tensile strength analysis confirmed that the degradation rate of the hourglass-like filter was faster than the connecting fibers, achieving progressive degradation and thus avoiding the polymer fragments from blocking vessel. Cytotoxicity and hemolysis assay demonstrated good biocompatibility of the filter. For 5 mm × 10 mm sized thrombus, in vitro simulated thrombus capture test showed that the mean trapping efficiency of the filter was 90%, which was comparable to traditional inferior vena cava filter. In conclusion, all results exhibited that the as-designed biodegradable inferior vena cava filter has a potential in clinical application for patients who are at temporary high risk of venous thromboembolism.

Migration of a fractured inferior vena cava filter strut to the right ventricle of the heart

Inferior vena cava (IVC) filters are increasingly used in patients with recurrent venous thromboembolism in whom anticoagulation is contraindicated or intolerable. Migration of fragments is a known complication of IVC filter use. We present a case of a 32-year-old man, who presented with right-sided chest pain believed to be caused by a migrated IVC fragment to the right ventricle. The filter was removed by an endovascular cook forceps with the assistance of intracardiac echocardiography. This case serves as an addition to the existing reports of successful removal of intracardiac fragments via minimally invasive endovascular approach, amid a larger number of intracardiac fragments that have been removed by an open-heart approach.

Development of a predictive model for 6 month survival in patients with venous thromboembolism and solid malignancy requiring IVC filter placement

PURPOSE

Our purpose was to develop a predictive model for short-term survival (i.e. <6 months) following inferior vena cava filter placement in patients with venous thromboembolism (VTE) and solid malignancy.

METHODS

Clinical and laboratory parameters were retrospectively reviewed for patients with solid malignancy who received a filter between January 2009 and December 2011 at a tertiary care cancer center. Multivariate Cox proportional hazards modeling was used to assess variables associated with 6 month survival following filter placement in patients with VTE and solid malignancy. Significant variables were used to generate a predictive model.

RESULTS

397 patients with solid malignancy received a filter during the study period. Three variables were associated with 6 month survival: (1) serum albumin [hazard ratio (HR) 0.496, P < 0.0001], (2) recent or planned surgery (<30 days) (HR 0.409, P < 0.0001), (3) TNM staging (stage 1 or 2 vs. stage 4, HR 0.177, P = 0.0001; stage 3 vs. stage 4, HR 0.367, P = 0.0002). These variables were used to develop a predictive model to estimate 6 month survival with an area under the receiver operating characteristic curve of 0.815, sensitivity of 0.782, and specificity of 0.715.

CONCLUSIONS

Six month survival in patients with VTE and solid malignancy requiring filter placement can be predicted from three patient variables. Our predictive model could be used to help physicians decide whether a permanent or retrievable filter may be more appropriate as well as to assess the risks and benefits for filter retrieval within the context of survival longevity in patients with cancer.

Endovascular Removal of Inferior Vena Cava Filters with Arterial Penetration

PURPOSE

To evaluate the safety and outcomes of endovascular percutaneous removal of inferior vena cava filters (IVCFs) with elements penetrating an artery.

MATERIALS AND METHODS

From an IVCF retrieval database, computerized tomographic scans of patients who underwent IVCF retrieval from 2011 to 2017 were reviewed for IVCF elements penetrating through the caval wall and into an adjacent arterial wall (AW) or penetrating into an adjacent arterial lumen (AL). Forty-two patients were identified, including 20 with elements penetrating into an AW and 22 with elements penetrating into an AL; 30 of these IVCFs were tip embedded.

RESULTS

All of the filters in both groups were removed. Of the arterial-interacting filters, 9 were removed with the use of standard techniques and 33 with the use of endobronchial forceps. Arterial access was obtained before removal in 3 patients (7%) with post-removal arteriography revealing no abnormalities, such as extravasation, pseudoaneurysm, or new fractured components. There was no significant difference between groups in tip embedding, retrieval technique, or fluoroscopy time.

CONCLUSIONS

Endovascular removal of IVCFs with elements that have penetrated into adjacent arterial walls or lumens can be performed safely in the majority of patients.

Differences in radial expansion force among inferior vena cava filter models support documented perforation rates

OBJECTIVE

Inferior vena cava (IVC) filters are used in patients at risk for pulmonary embolism who cannot be anticoagulated. Unfortunately, these filters are not without risk, and complications include perforation, migration, and filter fracture. The most prevalent complication is filter perforation of the IVC, with incidence varying among filter models. To our knowledge, the mechanical properties of IVC filters have not been evaluated and are not readily available through the manufacturer. This study sought to determine whether differences in mechanical properties are similar to differences in documented perforation rates.

METHODS

The radial expansion forces of Greenfield (Boston Scientific, Marlborough, Mass), Cook Celect (Cook Medical, Bloomington, Ind), and Cook Platinum filters were analyzed with three replicates per group. The intrinsic force exerted by the filter on the measuring device was collected in real time during controlled expansion. Replicates were averaged and significance was determined by calculating analysis of covariance using SAS software (SAS Institute, Cary, NC).

RESULTS

Each filter model generated a significantly different radial expansion force (P < .001), and force was distributed at significantly different rates (P < .001) during expansion. The largest radial expansion force at minimal caval diameter was seen in the Cook Platinum filter, followed by the Cook Celect and Greenfield filters. Radial force dispersion during expansion was greatest in the Cook Celect, followed by the Cook Platinum and Greenfield filters.

CONCLUSIONS

Differences in radial expansion forces among IVC filter models are consistent with documented perforation rates. Cook Celect IVC filters have a higher incidence of perforation compared with Greenfield filters when they are left in place for >90 days. Evaluation of Cook Celect filters yielded a significantly higher radial expansion force at minimum caval diameter, with greater force dispersion during expansion.

Utility of Retrievable Inferior Vena Cava Filters: A Systematic Literature Review and Analysis of the Reasons for Nonretrieval of Filters with Temporary Indications

OBJECTIVE

To investigate the use of retrievable inferior vena cava (IVC) filters in the current practice and analyze the causes of filter left in situ despite initial plans for retrieval.

METHODS

A systematic search of all English-language studies of retrievable IVC filters was conducted, including clinical trials and observational studies published between January 1984 and March 2016.

RESULTS

A total of 103 studies were identified, including 10 filter models in 20,319 patients. Placement indications were reported for 11,128 (54.8%) patients, including therapeutic (n = 6270; 56.3%) and prophylactic (n = 4858; 43.7%) indications. A total of 13,224 (65.1%) filters were left as permanent devices; 7095 (34.9%) filters were removed. The reasons for filter nonretrieval among the 5308 (40.1%) reported cases were primary permanent indication (21.2%; 1127/5308), death (19.4%; 1031/5308), ongoing pulmonary embolism (PE) protection (19.0%; 1011/5308), failed retrieval (13.7%; 725/5308), loss to follow-up (13.0%; 689/5308), discontinued care (4.4%; 235/5308), physician oversight (4.0%; 213/5308), patient morbidity (2.8%; 149/5308), and patient refusal (2.4%; 128/5308). A total of 7820 patients presented for filter retrieval, and 7095 filters (90.7%) were successfully removed, with a mean indwelling time of 106.6 ± 47.3 days. Breakthrough PE was reported in 2.1% (191/9169) of patients. Filter tilt, recurrent deep vein thrombosis, penetration, IVC thrombosis, migration, and fracture occurred in 7.7% (798/10,348), 7.1% (362/5092), 5.4% (379/7001), 3.9% (345/8788), 1.4% (160/11,679), and 0.5% (50/9509) of patients, respectively.

CONCLUSIONS

Approximately two-thirds of retrievable filters were not retrieved even though more than 85% of the filters were initially intended for temporary use. The major reasons for filter left in situ despite initial plans for retrieval were death, need for ongoing PE protection, failed retrieval, loss to follow-up, discontinued care, and physician oversight.

Inferior vena cava filter use and patient safety: legacy or science?

There has been a dramatic increase in vena cava filter (VCF) use over the past 20 years in the absence of evidence that filters provide a net patient benefit or are required in most cases. This increase is largely attributable to the availability of retrievable filters and expanded indications, particularly as primary prophylaxis in patients thought to be at high risk of pulmonary embolism. Substantial variability in VCF use, unrelated to patient clinical factors, has been shown between hospitals, from region to region, and among various countries. Despite the lack of direct evidence for the benefit of VCFs for any indication, it is appropriate to insert a retrievable VCF in patients with a recent proximal deep vein thrombosis and an absolute contraindication to therapeutic anticoagulation and then to remove the filter once the bleeding risk decreases and the patient has been anticoagulated. Unfortunately, a high proportion of retrievable filters are not removed, even after the reason for their placement has long passed. Retrievable filters are associated with substantial rates of complications if they are not removed, including penetration of the vena caval wall, fracture and embolization of filter fragments, and caval occlusion. Patient safety priorities and medical-legal concerns mandate careful selection of patients for VCF placement and removal shortly after anticoagulation has been initiated.

Retrievable IVC Filters: Comprehensive Review of Device-related Complications and Advanced Retrieval Techniques

Use of retrievable inferior vena cava filters (RIVCFs) has grown exponentially since their introduction into clinical practice, but many of these devices are not retrieved. Some are not retrieved due to poor clinical follow-up, but other devices remain in situ for extended periods because they present significant technical challenges during retrieval. Because of these and other factors, many of these devices were thus left in place permanently. However, recent data have placed a renewed emphasis on device retrieval due to increased risk of RIVCF-related complications, which are positively correlated with filter dwell time. Development of advanced filter retrieval techniques has had a significant impact on the removal of embedded RIVCFs, permitting retrieval of the majority of devices. The purpose of this article is to present an imaging and data review of the dominant device-related factors that complicate RIVCF retrieval and to describe the relevant advanced retrieval techniques to manage these factors. RIVCF imaging is frequently encountered in daily clinical practice via various imaging modalities. Therefore, diagnostic radiologists can play a vital role in identifying filter-related issues. Familiarity with the context for managing these issues in the interventional suite is essential for improving triage and care of patients with RIVCFs. ^© RSNA, 2017.

Vena Cava Filter Retrieval Rates and Factors Associated With Retrieval in a Large US Cohort

Background

Retrieval of vena cava filters (VCFs) is important for safety as complications increase with longer dwell times. This study assessed VCF retrieval rates and factors associated with retrieval in a national cohort.

Methods and Results

VCFs were identified by procedural codes from an administrative claims database. Patients were identified who had a VCF placement during a hospitalization from a national commercial administrative claims database. Indications for VCF placement were identified as pulmonary embolism with or without deep vein thrombosis, deep vein thrombosis only, or prophylactic. Patient demographic and clinical characteristics were included in proportional hazard regression models to find associations with early (90‐day) and 1‐year VCF retrieval. Initiation of anticoagulation and the correlation between time‐to‐retrieval and time‐to‐initiation of anticoagulation were observed. Of 54 766 patients receiving a VCF, 36.9% had pulmonary embolism, 43.9% had deep vein thrombosis only, and 19.2% had no apparent venous thromboembolism present. Over the 1 year of follow‐up, the cumulative incidence of VCF retrieval was 18.4%. Retrieval increased over time from a low of 14.0% in 2010 up to ≈24% in 2014. In adjusted time‐to‐event models, increasing age, differing regions, and some comorbidities were associated with poorer retrieval rates. Initiation of anticoagulation was poorly correlated with retrieval, with anticoagulation preceding retrieval by a median of 51 days while those without retrieval had a median of 278 days of exposure to anticoagulation.

Conclusions

VCF retrieval increased over the study period but remained suboptimal and was weakly correlated with anticoagulation initiation.

Indwelling and Retrieval Complications of Denali and Celect Infrarenal Vena Cava Filters

PURPOSE

To compare indwelling and retrieval complications of Denali and Celect filters placed in the infrarenal inferior vena cava (IVC).

MATERIALS AND METHODS

A retrospective study was conducted over 2 years at a single institution in which 171 Denali and 162 Celect filters were placed in 333 patients with a mean age of 62.3 years ± 15.7 (161 men; 48.3%). Filter indications included venous thromboembolic disease (n = 320; 96.1%) and surgical prophylaxis (n = 13; 3.9%). A jugular approach was used to place 303 filters (91.0%). Computed tomography (CT) follow-up, complications, and retrieval data were obtained.

RESULTS

Follow-up CT imaging was performed on 58 filters from each group with lower incidences of caval strut penetration (one vs 12) and filter tilt (one vs 15) in the Denali filter group (P = .002 and P < .001, respectively). There was no difference in incidences of breakthrough pulmonary embolism (P = .68). Retrieval attempts were performed on 43 Denali and 53 Celect filters with mean indwelling times at retrieval of 128.2 and 144.1 days, respectively (P = .40). Mean fluoroscopy time at retrieval was lower in the Denali group (3.1 min vs 6.0 min; P = .01). There were fewer cases of complex retrieval in the Denali group (n = 2 vs 10; P = .06). Tilt, fluoroscopy time, and air kerma were associated with complex retrieval (P = .04, P < .001, and P < .001, respectively). There was one Denali filter deployment complication that led to retrieval failure.

CONCLUSIONS

This study suggests that Denali filters are associated with lower incidences of strut penetration and filter tilt as well as shorter fluoroscopy time at retrieval compared with Celect filters when placed in the infrarenal IVC.