Filter Migration Research Articles

Parallel Butterworth and Chebyshev dip filters with applications to 3-D seismic migration

Dip filtering is a necessary part of accurate frequency‐space domain migration, so design and application of reliable and efficient filters are of practical as well as theoretical importance. Frequency‐space domain dip filters are implemented using Butterworth and Chebyshev algorithms. By transforming the product terms of the filter transfer function into summations, a cascaded (serial) Butterworth or Chebyshev dip filter can be made parallel, which improves computational efficiency. For a given order of filter, the cost of the Butterworth and Chebyshev filters is the same. However, the Chebyshev filter has a sharper transition zone than that of a Butterworth filter with the same order, which makes it more effective for phase compensation than a Butterworth filter, but at the expense of some wavenumber‐dependent amplitude ripples. Both implementations have been incorporated into 3-D one‐way frequency‐space depth migration for evanescent energy removal and for phase compensation of splitting errors; a single filter achieves both goals.

Prophylactic inferior vena cava filters in trauma patients at high risk: Follow-up examination and risk/benefit assessment

Purpose: The efficacy of prophylactic inferior vena cava filters in selected trauma patients at high risk has come into question in relation to risk/benefit assessment. To evaluate the usefulness of prophylactic inferior vena cava filters, we reviewed our experience and overall complication rate. Methods: From February 1991 to April 1998, the trauma registry identified 7333 admissions. One hundred eighty-seven prophylactic inferior vena cava filters were inserted. After the exclusion of 27 trauma-related deaths (none caused by thromboembolism), 160 patients were eligible for the study. The eligible patients were contacted and asked to complete a survey and return for a follow-up examination to include physical examination, Doppler scan study, vena cava duplex scanning, and fluoroscopic examination. The patients’ hospital charts were reviewed in detail. The indications for prophylactic inferior vena cava filter insertion included prolonged immobilization with multiple injuries, closed head injury, pelvic fracture, spine fracture, multiple long bone fracture, and attending discretion. Results: Of the 160 eligible patients, 127 were men, the mean age was 40.3 years, and the mean injury severity score was 26.1. The mean day of insertion was hospital day 6. Seventy-five patients (47%) returned for evaluation, with a mean follow-up period of 19.4 months after implantation (range, 7 to 60 months). On survey, patients had leg swelling (n = 27), lower extremity numbness (n = 14), shortness of breath (n = 9), chest pain (n = 7), and skin changes (n = 4). All the survey symptoms appeared to be attributable to patient injuries and not related to prophylactic inferior vena cava filter. Physical examination results revealed edema (n = 12) and skin changes (n = 2). Ten Doppler scan studies had results that were suggestive of venous insufficiency, nine of which had histories of deep vein thrombosis. With duplex scanning, 93% (70 of 75) of the vena cavas were visualized, and all were patent. Only 52% (39 of 75) of the prophylactic inferior vena cava filters were visualized with duplex scanning. All the prophylactic inferior vena cava filters were visualized with fluoroscopy, with no evidence of filter migration. Of the total 187 patients, 24 (12.8%) had deep vein thrombosis develop after prophylactic inferior vena cava filter insertion, including 10 of 75 (13.3%) in the follow-up group, and one patient had a nonfatal pulmonary embolism despite filter placement. Filter insertion complications occurred in 1.6% (three of 187) of patients and included one groin hematoma, one arteriovenous fistula, and one misplacement in the common iliac vein. Conclusion: This study’s results show that prophylactic inferior vena cava filters can be placed safely with low morbidity and no attributable long-term disabilities. In this patient population with a high risk of pulmonary embolism, prophylactic inferior vena cava filters offered a 99.5% protection rate, with only one of 187 patients having a nonfatal pulmonary embolism. (J Vasc Surg 1999;30:484-90.)

Determination of Inferior Vena Cava Diameter in the Angiography Suite: Comparison of Three Common Methods

Significant inferior vena cava (IVC) filter migration has been associated with deployment of some filter types in IVCs measuring more than 28 mm in diameter at inferior vena cavography. The purposes of this study were to (a) determine if significant differences exist between IVC measurements obtained using a gold standard technique and two other widely accepted methods, and (b) if differences exist, how often do these differences cause incorrect IVC sizing around a diameter of 28 mm, with its associated filter migration issues. One hundred thirteen consecutive inferior vena cavograms were retrospectively reviewed. The transverse diameter of the infrarenal IVC was determined by using a calibrated intravascular catheter (the gold standard), subtraction of 20% from the measured transverse IVC diameter on a cut-film radiograph, and a radiopaque ruler placed immediately posterior to the patient. The concordance correlation of the 20% magnification method versus internal calibration was 0.94. Kappa analysis to determine agreement at a diameter of 28 mm yielded a Kappa coefficient of 0.490. The concordance correlation of an external ruler versus internal calibration was 0.43, with a Kappa coefficient of 0. The poor Kappa correlations for both methods demonstrate that they are unreliable in identifying megacava. Inferior vena cavography prior to IVC filter placement should be performed with a calibrated intravascular catheter.

Acute Upper Extremity Deep Venous Thrombosis: Safety and Effectiveness of Superior Vena Caval Filters

To evaluate the safety and effectiveness of percutaneous filter placement in the superior vena cava for prevention of pulmonary embolism (PE) due to acute upper extremity deep venous thrombosis (DVT) in patients with contraindications to or unsuccessful anticoagulation. Forty-one patients with acute upper extremity DVT and contraindications to or unsuccessful anticoagulation underwent percutaneous placement of a superior vena caval filter for prevention of PE. Four types of filters were used. Follow-up chest radiographs were used to detect filter migration, dislodgment, and fracture. Placements of central venous and Swan-Ganz catheters after filter insertion were recorded. Patients were followed up clinically for evidence of superior vena cava syndrome and PE. Kaplan-Meier survival rates were determined. Follow-up was 1 day to 221 weeks. No complications such as filter migration, dislodgment, or fracture occurred (median follow-up, 12 weeks). No patients developed clinical evidence of PE due to upper extremity thrombosis or superior vena cava syndrome (median follow-up, 15 weeks). Catheters were placed subsequent to filter placement in 23 patients (56%) without complication. Percutaneous filter placement in the superior vena cava is a safe and effective method for preventing symptomatic PE due to acute upper extremity DVT in patients in whom therapeutic anticoagulation has failed or is contraindicated.

Suprarenal filter placement

Purpose: This study was undertaken to determine the clinical outcomes for patients with Greenfield filters placed in the suprarenal (SR) inferior vena cava (IVC). Methods: We collected data prospectively from annual follow-up evaluations of patients with filters. Patients underwent venous color-flow duplex examinations of the IVC and lower extremities, abdominal radiographs, and physical assessment. The outcomes for those patients with filters in the SR IVC were compared with the outcomes previously reported and with the outcomes for patients with filters in the infrarenal cava. Results: SR placement accounted for 7.6% (148/1932) of all filter placements. Follow-up data were available for 73 placements, or 49%. No cases of renal dysfunction were related to filter placement. The rate of recurrent pulmonary embolism (PE) was 8%, and the rate of long-term caval occlusion was 2.7%. These rates did not differ statistically from the rates for patients with infrarenal filters ( P > .05). Male patients tended to be older by 15 years, to have more recurrent PE, and to experience more filter migration (6 vs 2 mm). Failure of SR filters to prevent PE was associated statistically with the primary indication for placement. Recurrent PE was the indication in 5 of 6 patients who sustained PE after SR filter placement ( P = .007). Filter limb fracture was seen only with the stainless-steel Greenfield filter. Conclusion: Greenfield filters placed above the renal vein provide protection from PE with a minimal risk of occlusion. Twenty-five years of experience with Greenfield filters shows that they are safe and effective both in young female patients of child-bearing potential and in all patients with appropriate indications for SR placement. (J Vasc Surg 1998;28:432-8.)

Suprarenal Vena Caval Filter Placement: Follow-up of Four Filter Types in 22 Patients

To determine if suprarenal placement of inferior vena cava (IVC) filters is associated with renal dysfunction or other complications. Case files of all patients with suprarenal vena caval filter placement since 1985 were reviewed for clinical and biochemical evidence of renal dysfunction and renal vein thrombosis. The occurrence of associated complications, including IVC occlusion, filter fracture, device migration, and recurrence of pulmonary embolism was also recorded. Twenty-two (2.9%) of 764 IVC filters were implanted above the renal veins: titanium Greenfield filter modified hook (TGF-MH) (n = 16), LGM type I (n = 2), LGM type II (n = 2), and Bird's Nest (BN) type I (n = 2). Reasons for suprarenal filter placement included thrombus to the level of the renal veins (n = 9), failure or poor position of the infrarenal filter (n = 6), pregnancy or intent of pregnancy (n = 4), and the malpositioning of BN filters above the renal veins (n = 2). A single patient demonstrated evidence of transient renal dysfunction. Pulmonary embolus was found at autopsy in one patient. Abdominal radiographs were obtained at follow-up of 18 patients and demonstrated a 2 cm or more migration of the filter in five patients (27.7%). This rate of migration was significantly different from the 3% migration rate reported by the authors' institution in the follow-up of 320 infrarenal IVC filters. There was one filter fracture (5.5%.) and penetration of the IVC occurred in one patient (5.5%). Follow-up indicates suprarenal IVC filter placement is safe, and no evidence of permanent renal dysfunction after placement was found. Filter migration was the most frequent complication, but no clinical sequelae were noted with these patients.

Long-term results of vena cava filters: experiences with the LGM and the Titanium Greenfield devices.

Vena cava filter (VCF) application is the method of choice to prevent recurrent pulmonary embolism in patients with deep venous thrombosis. Because of the reported complications after VCF placement we summarize our long-term follow-up results with the LGM and Titanium Greenfield (TG) devices. Eighty-seven LGM VCF and 17 TG VCF were placed in 104 patients (average age 64 years). The follow-up examinations were performed by color-coded duplex sonography, plain radiographs, cavography, and computed tomography (CT). The maximum observation time was 81 months. Filter migration occurred in 11% (8/76) of the LGM VCF and 15% (2/13) of the TG VCF. Vena cava thrombosis was seen in 17% (13/76) of the patients with an LGM VCF and in 31% (4/13) of those with a TG VCF. The patency rate was 95% (72/76) for the LGM VCF and 92% (12/13) for the TG VCF. Pulmonary embolism was noted in 3 patients after LGM VCF insertion and in no patient after TG VCF insertion. A VCF should only be inserted in a patient after pulmonary embolism and when there is strict proof of the indication.

Duplex-directed vena caval filter placement: Report of initial experience

Background: Fluoroscopy, cost, and patient transport contribute to difficulties occasionally associated with the placement of vena caval filters. Follow-up data in the literature document the use of duplex ultrasonography in visualizing the filter and determining caval patency. Filter placement at the bedside or in the vascular laboratory with duplex ultrasonography may simplify this common procedure. We have attempted to define the feasibility of this method. Methods: Patients referred to the vascular surgery service for vena caval interruption were evaluated for ability to visualize the renal veins and inferior vena cava. Location of renal veins, maximum diameter of the vena cava, and presence or absence of thrombus were documented. If visualization was adequate, placement was performed at the bedside for patients in intensive care or in the vascular laboratory for nonmonitored patients. The initial 10 patients and subsequent patients in whom there was a question of adequate deployment underwent completion abdominal roentgenography. Patient follow-up was difficult. Duplex ultrasonography was used to assess migration, thrombus adherent to the filter, and vena caval patency. Patients in whom filter placement was prophylactic were given anticoagulants at the discretion of the primary physician. Inadequate visualization or vena caval size greater than 28 mm prompted fluoroscopic placement of the vena caval filter, because only Greenfield titanium filters were used in the study. Results: Twenty-nine patients were referred for vena caval interruption. Inadequate visualization occurred in four obese patients, and filters were placed by fluoroscopy. There were no vena caval measurements greater than 24 mm. Twenty-five filters were placed without technical difficulty. One filter tilted into the right renal vein, requiring a suprarenal filter placed by fluoroscopy. Patient retrieval for follow-up has been difficult, but by ultrasonograhy there has been one vena caval thrombosis and no major filter migration. There have been no reported pulmonary emboli other than the one patient with initial tilt of the filter. Conclusions: Placement of vena caval filters is feasible with duplex ultrasonography. Visualization is the only limiting condition to placement and occurs rarely. Reducing the need for fluoroscopy, lowering costs, and not needing to transport the critically ill patient support the use of this system. Intravascular ultrasonography in selected patients may eliminate the need for fluoroscopic placement of vena caval filters. (Surgery 1998;123:470-4.)

Long-term results of the Simon nitinol inferior vena cava filter.

The aim of this study was to evaluate the clinical efficacy, mechanical stability, and safety of the Simon nitinol inferior vena cava filter (SNF). The SNF was inserted in 114 consecutive patients at two institutions for prophylaxis of pulmonary embolism (PE). Clinical follow-up data were obtained retrospectively on all patients, and 38 patients underwent a dedicated radiologic follow-up protocol consisting of abdominal radiography, Doppler sonography, and CT. There was no immediate complication following filter insertion. Fifty patients died, on average, 5.6 (1-23) months after filter insertion, and 64 patients were alive, on average, 27 (3-62) months after filter insertion. Recurrent pulmonary embolism was documented in 5 patients (4.4 %) but originated distal to the filter in 1 patient. Deep venous thrombosis (DVT) was documented in 5.3 %, thrombosis at the access site in 3.5 %, and thrombosis of the inferior vena cava in 3.5 %. The rate of thromboembolic complications was similar in patients who did receive long-term anticoagulation and in those who did not. Radiologic follow-up showed no filter migration after, on average, 32 (5-62) months. A CT examination showed that struts of the SNF had penetrated the vena cava in 95 %, and were in contact with adjacent organs in 76 %; however, there were no clinical symptoms attributable to the filter. Filters were in an eccentric position in 63 % and partial filter disruption was found in 16 %; however, this did not affect filter function. The rate of recurrent pulmonary embolism after insertion of the SNF is 2.4 % per patient per year. Regardless of long-term anticoagulation, the rate of caval thrombosis is acceptably low. Except for occasional access-site thrombosis, no other filter-related morbidity was observed.

Determination of Filter Cake Properties by Nuclear Magnetic Resonance

ABSTRACT Low resolution nuclear magnetic resonance (NMR) is used to investigate the porosity and permeability of filter cakes. Porosity is determined by free induction decay measurements of the fully saturated packings. NMR spin-lattice and spin-spin relaxation measurements were performed on the samples. It is shown that the permeability of the packed beds correlates strongly with the three material parameters of the sample: porosity ε and the relaxation time constants T1 and T2 All three parameters can be determined with a low resolution NMR spectrometer. Validation of the approach is achieved from flow experiments and analytical determination of porosity and permeability. After calibration, the new method allows an easy and rapid determination of filter cake properties under different process conditions. Changes of porosity and permeability of the filter cake during processing can be studied systematically. Filtration problems, such as compressibility of the filter cake or migration of small particles plugging the filter cake, can be analyzed with this method.

Vena cava filter ensnarement and delayed migration: An unusual series of cases

Purpose: To review delayed and guidewire-induced morbidity associated with vena cava filters. Methods: The records from the Johns Hopkins Hospital, a tertiary care referral center, of all patients who had vena cava filter complications from August 1993 through July 1996 were retrospectively reviewed. Results: Five patients had filter migration or ensnarement with a guidewire. One patient had delayed extrusion of a filter strut into the duodenum. Four patients had filters ensnared by guidewires, including one during initial filter placement and one several years after placement. Conclusions: Delayed complications of vena cava filters should be considered whenever unusual patient signs or symptoms cannot be easily explained, even in the absence of a history of filter placement. To prevent guidewire ensnarement of filters, simple techniques should modify endovascular procedures when vena cava filters are present. (J Vasc Surg 1997;26:869-74.)

The Tempofilter®: A Multicenter Study of a New Temporary Caval Filter Implantable for up to Six Weeks

A multicenter study was conducted to evaluate a new temporary caval filter (Tempofilter) designed to be implanted for up to 6 weeks. A total of 66 patients with a mean age of 51.8 years were enrolled in the study. All had documented high risk of pulmonary embolism: severe deep venous thrombosis in 89.5% of cases and previous symptomatic pulmonary embolism in 65% of cases. Filter placement was performed in association with a surgical or obstetrical procedure in 68.5% of cases. The indication for filter placement was contraindication to or failure of anticoagulant therapy in 85% of the cases. The mean duration of implantation was 29.9 days. Pulmonary embolism was not observed during the implantation period. Partial thrombosis of the filter was observed in 15% of cases due to trapping of clots by the filter. Thrombosis did not hinder filter removal when attempted. Filter-related complications were minor. Filter migration occurred in only 7.5% of cases. Migration never led to complications and did not hinder filter removal. In all cases migration was due to specific, preventable causes. The results of this study show that the Tempofilter is not only safe and easy to use but also effective in preventing pulmonary embolism. A significantly longer maximum implantation time is a major advantage of the Tempofilter over conventional temporary filters. We believe that this filter can be used for temporary protection against the risk of pulmonary embolism particularly in young patients and in a surgical setting.

An improved process for development and testing of vena caval filters: The percutaneous steel Greenfield filter

Background. The purpose of this study was to develop a reduced profile stainless steel Greenfield filter with an over-the-wire delivery system and to compare its performance with the existing Food and Drug Administration-approved Greenfield filters. In addition, we wanted to standardize a system for evaluating filter prototypes. Methods. Percutaneous stainless steel filters with various hook configurations were evaluated for efficacy and safety in four in vitro modules designed to reproduce potential liabilities experimentally. Animal studies to assess thrombus capture and resolution, filter stability, migration, and hemodynamics were completed in 4 dogs and 38 sheep. Results. Mathematical modeling suggested that hook angle was the most relevant factor in improving resistance to migration. Prototypes that varied with respect to hook length and angle were evaluated in both the in vitro testing unit and in sheep. The stainless steel filter with two downward directed hooks provided clot capture comparable with the current Greenfield filter, maintenance of flow, and resistance to fatigue and corrosion while providing significant resistance to migration and penetration (p < 0.05). Conclusions. The percutaneous stainless steel Greenfield filter with the alternating hook design provides a reduced profile device that can be placed over a wire to improve positioning. The use of a standardized testing system reduced both the time and cost of bringing this new device to the market.

Does Cervical Spinal Cord Injury Induce a Higher Incidence of Complications after Prophylactic Greenfield Inferior Vena Cava Filter Usage?

To determine whether acute cervical spine injury represents a risk factor for complications from prophylactic placement of current generation Greenfield inferior vena cava (IVC) filters. A retrospective chart review performed during a 7-year period identified 11 patients with acute cervical spinal cord injuries who underwent prophylactic Greenfield IVC filter insertion. Specific complications evaluated included symptomatic pulmonary embolism (PE), migration, filter base diameter changes, caval perforation, and thrombosis. The amount of migration and changes in filter base dimension were compared statistically with a control population of IVC filter patients (n = 16) without cervical spine injuries. Filter migration (> 10 mm) was the most common complication (46%). Migration usually is caudally directed (64%), may occur early (36% moved > 10 mm within a 30-day period), and is often asymptomatic. The prevalence of filter migration greater than 30 mm was 27%. The average amount of migration for the subpopulation under study was greater than that seen with the control population (P < .05). No statistically significant change in filter base size occurred. The study population also had rates of PE (9%-18%), caval perforation (9%), and IVC thrombus formation (18%) that were higher than the rates in historical controls. The majority of patients with these complications received vigorous pulmonary toilet (46%), including "quad coughs" or cardiopulmonary resuscitation (18%). Acute cervical spinal cord injury and the associated supportive care may be associated with an increased risk for caudal IVC filter migration, IVC perforation, caval thrombosis, and PE.

The use of inferior vena cava filters in pediatric patients for pulmonary embolus prophylaxis.

To report our experience with inferior vena cava (IVC) filters in pediatric patients. Over a 19-month period, eight low-profile percutaneously introducible IVC filters were placed in four male and four female patients aged 6-16 years (mean 11 years). Indications were contraindication to heparin in six patients, anticoagulation failure in one, and idiopathic infrarenal IVC thrombosis in one. Six of the eight devices placed were titanium Greenfield filters. One LGM and one Bird's Nest filter were also placed. Two of the filters were introduced via the right internal jugular vein by cutdown, and the remainder were placed percutaneously via the right internal jugular vein or the right common femoral vein. Patients received follow-up abdominal radiographs from 2 to 13 months after IVC filter placement. All filters were inserted successfully without complication. Three of the patients died during the follow-up period: two due to underlying brain tumors at 2 and 12 months and a third at 6 weeks due to progressive idiopathic renal vein and IVC thrombosis. The remaining five patients were all alive and well at follow-up without evidence of IVC thrombosis, pulmonary emboli, or filter migration. IVC filter placement using available devices for percutaneous delivery is technically feasible, safe, and effective in children.

Follow-up after insertion of bird's nest inferior vena caval filters : Starok MS, Common AA (Department of Medical Imaging, University of Toronto, St. Michael's Hospital, 30 Bond Street, Toronto, ON M5B 1W8, Canada). Can Assoc Radiol J 1996;47:189–194

To determine the long-term clinical and radiographic outcome of patients who undergo insertion of a Gianturco-Roehm Bird's Nest vena caval filter (Cook Inc., Bloomington, Ind.).The medical records of 40 patients who, over a 34-month period, underwent insertion of a Bird's Nest filter were reviewed and the reasons for filter insertion determined. The causes of any subsequent deaths were noted, and the autopsy findings, when available, were reviewed. Surviving patients were contacted, and 12 were willing to return for follow-up imaging, which consisted of plain radiography, real-time ultrasonography, colour Doppler imaging and contrast-enhanced computed tomography. Changes in filter position, the presence of thrombus and perforation of the vessel wall by the filter struts were documented.All 10 patients who underwent filter insertion while in an intensive care unit (ICU) died, an average of 22 days after the procedure. Eleven other patients also died. Recurrent pulmonary embolism was not suspected in any of these patients, and five autopsies revealed no caval thrombosis. Imaging studies in 12 of the surviving patients revealed no occlusion of the inferior vena cava and no filter migration; however, the vena caval wall was perforated in all of these patients. Nonocclusive intrafilter thrombus was detected by colour Doppler imaging in three patients.In this small group of patients the Bird's Nest filter was effective in preventing recurrent pulmonary embolism and caused less caval thrombosis than has previously been suspected, although intrafilter clot was found in 25% of the patients who underwent follow-up imaging. Colour Doppler imaging is the method of choice for detecting nonocclusive thrombus with this type of filter. Perforation of the caval wall was universal but not clinically symptomatic. Finally, guidelines should be established to ensure the cost-effective use of inferior vena caval filters in ICU patients.

Neutrophil activation and chemotaxis after in vitro treatment with perfluorocarbon

The in vitro effects of perfluorocarbon (PFC) on human neutrophil activation and chemotaxis were examined. Neutrophils were incubated, with and without PFC, and were analyzed for chemotaxis through 5-μm and 8-μm pore filters. Neutrophil activation was quantitated by flow cytometry. Activation studies showed that PFC-treated neutrophil samples (n = 6) produced only 39.83% ± 25.9% (mean ± SD) of matched control (n = 6) fluorescence. Chemotaxis studies showed that PFC-treated neutrophil samples (n = 8) had migration of only 18.63% ± 6.5% (of control values) of neutrophils to the outer boundary of the 5-μm filters (n = 8 controls). The 8-μm pore filter migration (n = 8) was similarly low, with a mean outer boundary migration count of only 26% ± 19.8% of the control (n =8) value. Thus, neutrophils exposed to perfluorocarbon produce significantly less detectable H2O2 (P < .001) and have a significantly lower chemotactic response (P < .001).

Superior vena caval Greenfield filters: Indications, techniques, and results

This study assessed the clinical feasibility of placement of the titanium Greenfield filter within the superior vena cava (SVC) in patients with upper extremity deep venous thrombosis and evaluated the short-term results. During the past 14 months, we have encountered 6 patients who had upper extremity central venous thrombosis in whom anticoagulation was deemed either contraindicated or ineffective in preventing recurrent pulmonary embolism. All patients underwent percutaneous insertion of a Greenfield filter into the SVC for prophylaxis for pulmonary embolism. Two of these patients had already undergone insertion of an inferior vena cava filter and two other patients had simultaneous insertion of SVC and inferior vena caval filters. No complications such as filter migration, misplacement, excessive hemorrhage, or pneumothorax occurred. Two patients subsequently underwent uncomplicated insertion of a Swan-Ganz catheter despite the presence of the filter. Two patients died of unrelated causes without clinical evidence of complications related to the filter. During the follow-up period from 4 to 14 months, there was no clinical evidence of pulmonary embolism in the remaining four patients. This procedure can be performed safely and is effective for the prevention of pulmonary embolism in patients with upper extremity venous thrombosis.

Bird's Nest Inferior Vena Caval Filter Migration into the Duodenum: A Rare Cause of Upper Gastrointestinal Bleeding

Purpose: To report the first case of a potentially catastrophic complication of vena caval interruption with a bird's nest filter. Methods and Results: A 55-year-old Saudi patient presented with hypovolemic shock from massive upper gastrointestinal hemorrhage. Endoscopy identified a metallic object penetrating the duodenum. Five years earlier, the patient had a bird's nest vena caval filter inserted for recurrent pulmonary embolism. During emergent laparotomy, a broken filter wire was found projecting into the duodenum, where it had induced three profusely bleeding ulcers. The wire was transected and the ulcers oversewn. A hook projecting from the inferior vena cava (IVC) was also cut flush with the vessel wall, but the IVC was not opened nor the filter replaced. The patient's postoperative course was complicated by deep venous thrombosis, but he recovered and is asymptomatic on warfarin anticoagulation after 1 year. Computed tomography (CT) at 1-year follow-up confirmed no further migration of the filter. Conclusion: This event reinforces the need to monitor patients with IVC filters over the long term, preferably using CT scanning, and to consider filter migration as a possible cause of upper gastrointestinal bleeding.

Long-term follow-up of the Günther basket inferior vena cava filter: does mechanical instability cause complications?

The Günther basket inferior vena cava filter (GBF) has been withdrawn from the market because of its mechanical instability, but a number of patients still live with the device. In a two-center study, we evaluated the long-term follow-up of the GBF, based on clinical data in 78 patients, and on imaging studies including plain radiographs, Doppler ultrasound, angiography, or computed tomography (CT) in 50 patients. In a mean period of 3 years, pulmonary embolism was diagnosed in five patients (6.4%), with an overall rate of 0.02 embolic episodes per patient per year. None of these patients required hospitalization, and there were no deaths due to pulmonary embolism. Inferior vena cava thrombosis was documented in three patients (3.9%), and occlusive venous thrombosis at the access site in seven patients (9%). Spontaneous migration was documented in 43% of the examined filters and spontaneous disruption in 77%. Dislocated filter fragments were localized by CT in the adjacent retroperitoneum in 11%, in the aortic lumen in 2%, and in a peripheral pulmonary artery in 7%. None of the patients had symptoms attributable to filter migration or disruption. Our results indicate that the rate of clinically relevant complications with the GBF is no higher than with other vena cava filters. Because mechanical instability of the GBF had no clinical consequences, we conclude that patients who live with this device may be observed and treated in a manner similar to patients with other vena cava filters.