Filter Tilt Research Articles

Cone over Guide Wire Technique for Difficult IVC Filter Retrieval

Retrievable inferior vena cava (IVC) filters are placed in patients who are at temporary increased risk for pulmonary embolism, with or without contraindication for anticoagulation, with the expectation of subsequent removal. The failure to retrieve nonpermanent IVC filters is an increasingly encountered dilemma for vascular interventionalists. One of the more common causes of technical failure of retrieval is the presence of tilt in the orientation of the IVC filter, which may result in the retrieval hook abutting the wall of the IVC, preventing contact with the removal system [1]. This issue may be compounded by endothelialization of the filter hook [2]. We describe a nonconventional method for the retrieval of tilted IVC filters in two patients. This method uses a femoral access site that is contralateral to the direction of filter tilt in addition to the right internal jugular vein (IJV) access site. A cone-over-guide wire is then used to retrieve the filter, which has been realigned to the caval axis by the gentle application of tension on the guide wire ends. This technique can be used for filters of both the half-basket and double-basket design, when conventional and other nonconventional techniques fail and may make retrieval difficulties pertaining to filter hook endotheliazliation less relevant.

Prospective implementation of an algorithm for bedside intravascular ultrasound-guided filter placement in critically ill patients

Although contrast venography is the standard imaging method for inferior vena cava (IVC) filter insertion, intravascular ultrasound (IVUS) imaging is a safe and effective option that allows for bedside filter placement and is especially advantageous for immobilized critically ill patients by limiting resource use, risk of transportation, and cost. This study reviewed the effectiveness of a prospectively implemented algorithm for IVUS-guided IVC filter placement in this high-risk population. Current evidence-based guidelines were used to create a clinical decision algorithm for IVUS-guided IVC filter placement in critically ill patients. After a defined lead-in phase to allow dissemination of techniques, the algorithm was prospectively implemented on January 1, 2008. Data were collected for 1 year using accepted reporting standards and a quality assurance review performed based on intent-to-treat at 6, 12, and 18 months. As defined in the prospectively implemented algorithm, 109 patients met criteria for IVUS-directed bedside IVC filter placement. Technical feasibility was 98.1%. Only 2 patients had inadequate IVUS visualization for bedside filter placement and required subsequent placement in the endovascular suite. Technical success, defined as proper deployment in an infrarenal position, was achieved in 104 of the remaining 107 patients (97.2%). The filter was permanent in 21 (19.6%) and retrievable in 86 (80.3%). The single-puncture technique was used in 101 (94.4%), with additional dual access required in 6 (5.6%). Periprocedural complications were rare but included malpositioning requiring retrieval and repositioning in three patients, filter tilt >/=15 degrees in two, and arteriovenous fistula in one. The 30-day mortality rate for the bedside group was 5.5%, with no filter-related deaths. Successful placement of IVC filters using IVUS-guided imaging at the bedside in critically ill patients can be established through an evidence-based prospectively implemented algorithm, thereby limiting the need for transport in this high-risk population.

The Günther-Tulip Retrievable Filter: A Method for Assessing Tilting of the Filter

Tilting of the Günther-Tulip filter may be responsible for failure or difficulty to retrieve. Assessment of the filter tilt can be difficult when only AP imaging is available. This study is performed in vitro to develop a simple method to assess the Günther-Tulip filter for tilting. A model consisting of a plastic tube was used to simulate vena cava. A Günther-Tulip filter was placed centred or tilted within the tube at various positions and radiograms were taken in AP, lateral, and craniocaudally angled projections. The images were analysed to determine the actual degree of tilt, the distance between the limb hooks on AP radiograms and the craniocaudal angulation degree needed to align the limb hooks linearly. When the filter was centred or tilted laterally, all limb hooks of the filter were aligned linearly on AP radiograms. When the filter was tilted in AP or oblique direction, linear alignment of the limb hooks was lost and the ventral and dorsal limb hooks showed separation on AP projection. The amount of separation and the craniocaudal angles to align the filter hooks corresponded to actual tilt angles. Loss of linear alignment of limb hooks in AP radiograms may suggest the presence of tilt in the AP plane. Significant separation of limb hooks should be alarming for significant filter tilt, and further evaluation of the filter position by CT scan or lateral cavogram should be obtained prior to planning of the retrieval.

Abstract No. 273: Computerized modeling of the effect of vena cava filter (VCF) tilt on filter performance

Abstract No. 273: Computerized modeling of the effect of vena cava filter (VCF) tilt on filter performance

Short- and Long-term Retrievability of the Celect Vena Cava Filter: Results from a Multi-institutional Registry

To evaluate retrievability of the Celect vena cava filter over time and to assess the safety of the retrieval procedure in a prospective multicenter registry. Between October 2005 and March 2008, Celect filters were placed in 95 patients (61 men; mean age, 51 years +/- 18.5) with a temporary need for an inferior vena cava (IVC) filter. All patients satisfied requirements for filter placement; the primary indications for placement were pulmonary embolism (PE) with a contraindication to or failure of anticoagulation (n = 40), high risk for further PE (n = 29), trauma (n = 23), or massive PE with residual deep vein thrombosis and risk for further PE (n = 3). Filter orientation, vena cava injury, and other device-related incidents were evaluated at implantation and retrieval. The degree of difficulty associated with retrieval was also assessed. Filter retrieval was attempted in 58 patients (mean indwell time of 179 days; median, 168.5 d; range, 5-466 d). Fifty-six filters (96.6%) were successfully retrieved. Unsuccessful retrieval attempts were attributed to filter tilt (n = 1) or excessive tissue growth with the hook embedded in the endothelium (n = 1). No adverse events were associated with the inability to retrieve these filters. A Kaplan-Meier product-limit survival estimate revealed that the probability of successful filter retrieval remained at 100% at 50 weeks and at more than 74% at 55 weeks after implantation. No adverse events were related to the retrieval procedures. Retrieval of the Celect filter was performed safely as long as 466 days after implantation.

Technical Success and Safety of Retrieval of the G2 Filter in a Prospective, Multicenter Study

To assess the technical success and safety for retrieval of the G2 filter. The authors performed a prospective, multicenter study of 100 patients with temporary indication for caval interruption. Patients were enrolled consecutively between December 2005 and July 2006. There were 67 men and 33 women with a mean age of 52.1 years (range, 19-82 years). Indications for filter placement were trauma (n = 56), perioperative risk (n = 16), and medical indications (n = 28). Forty-two patients had venous thromboembolism at filter placement. Fifty-eight filters were placed prophylactically. Retrieval was attempted in 61 patients. Fifty-eight of the 61 filters (95%) were successfully retrieved after a mean dwell time of 140 days (range, 5-300 days). In all failed retrievals, the filter tip was against the caval wall. There was no difference in dwell times between successful and unsuccessful retrievals. Although there were no cases of cranial migration, caudal migrations were observed in 12% of cases (10 of 85 patients with a complete data set). Other device-related complications included filter fracture (1/85, 1.2%), filter tilt of more than 15 degrees (15/85, 18%), and leg penetration (16/61, 26%). The recurrent pulmonary embolism (PE) rate was 2%, with no PE in the 30-day period after filter retrieval. Retrieval of the Recovery G2 filter was safe and successful in most patients. Caudal migration was observed as an unexpected phenomenon.

Balloon-assisted Removal of Tilted Inferior Vena Cava Filters with Embedded Tips

The successful removal of most retrievable inferior vena cava (IVC) filters requires the capture of the filter apex. The severely tilted filter with an apex in contact with the caval wall and covered by an endothelial cap represents a major technical challenge to removal. While a variety of techniques to deal with this problem have been reported, most require complex wire manipulations or the use of rigid endobronchial forceps. This article describes the successful use of a standard angioplasty balloon to free the apex of severely tilted filters with endothelial apical caps. A retrospective review of those patients who presented for removal of their Bard Recovery or G2 IVC filter between June 2005 and August 2008 was performed. Imaging studies and medical records were reviewed for those patients who had their IVC filters removed using the balloon-assisted technique. The presence of filter tilt and movement as well as the outcome of the technique was recorded for each case. Forty-eight Recovery and 209 G2 filters presented for removal. Ten of these 257 filters (3.6%) were found to be severely tilted with filter apex embedded into the wall of the cava. Eight of these filters were successfully removed using the balloon-assisted technique. No complications resulting from the technique occurred. Balloon-assisted removal of severely tilted embedded G2 and Recovery filters is an effective technique that can be performed using tools commonly available and familiar to most interventionists.

Comparison of the Recovery and G2 Filter as Retrievable Inferior Vena Cava Filters

To compare the technical success of the Recovery and G2 filters as retrievable inferior vena cava (IVC) filters. Recovery (n = 128) and G2 (n = 113) filters were placed in the IVCs of 241 patients with the intent of retrieval. The referring physician and/or patient were contacted at 6-month intervals to ensure filter retrieval when indicated. The Recovery and G2 filter groups were compared regarding technical success of filter placement, technical success of attempted retrieval, filter tilt, filter migration, filter fracture, and filter efficacy. Filter placement was technically successful in 95% of Recovery filters (n = 122) and 100% of G2 filters (n = 113). Recovery filter retrieval was attempted in 55% of patients (n = 71) at a mean of 228 days (range, 0-838 d) after filter placement. G2 filter retrieval was attempted in 55% of patients (n = 62) at a mean of 230 days (range, 7-617 d) after filter placement. Technical success rates of filter retrieval were 94% (n = 67) and 97% (n = 60) in the Recovery and G2 filter groups, respectively. The G2 filter group had significantly fewer cases of (i) filter tilt at placement, (ii) filter tilt at attempted retrieval, and (iii) filter fracture than the Recovery filter group. In the G2 filter group, there was a significantly higher technical success rate of filter placement and there were more cases of caudal filter migration than in the Recovery filter group. Compared with the Recovery filter, the G2 filter is associated with significantly less filter fracture and tilt, greater technical success of filter placement, and more caudal filter migration.

Long-term Retrieval Success Rate Profile for the Günther Tulip Vena Cava Filter

To evaluate the likelihood of successful retrieval of the Günther Tulip vena cava filter after various implant durations (up to 494 days). Retrievable Günther Tulip filters were placed in 554 patients. All patients satisfied requirements for filter placement; the primary indication for placement was specified for 394 patients (71%), as follows: unspecified trauma (n = 164), bariatric procedures (n = 128), orthopedic procedures (n = 36), and other (n = 66). Filter tilt and vena cava injury were assessed at implantation. Filters were not repositioned after placement. At retrieval, filter orientation, vena cava injury, other device-related incidents, and the degree of difficulty associated with retrieval were reported. Filter retrieval was attempted in 275 patients and successful in 248 (90.2%). The mean filter indwell time was 58.9 days (range, 3-494 days). Unsuccessful retrievals (n = 27) were attributed primarily to improper hook orientation (n = 10) or excessive tissue in-growth at the filter legs (n = 16). Of the remaining 279 patients, 223 withdrew from the study, 41 were associated with a decision to keep the filter as a permanent device, 13 died for reasons unrelated to the study, and two had no reported endpoint data. A Kaplan-Meier product-limit survival estimate revealed that the probability of successful device retrieval remained greater than 94% at 12 weeks and greater than 67% at 26 weeks. This study contributes to the body of clinical data related to retrievable filters, demonstrating reliable retrieval rates at 12 weeks, with successful retrievals up to 17 months after implantation.

Optional Vena Cava Filter with Disengaging Centering Struts: Retrieval in an Animal Model

An optional inferior vena cava (IVC) filter prototype was evaluated for safety and long-term retrievability as an initial feasibility study in an animal model. This filter has four centering struts that have the ability to disengage from the filtering cone portion, allowing the legs to slide out of endothelial growth. Retrieval of six filters in three animals was successful up to 27 weeks. There was no substantial filter tilt, migration, or IVC damage. In conclusion, this filter design may help overcome some of the shortcomings in currently approved optional IVC filters, including long-term retrieval difficulties, tilting, or migration.

Response to “Failed Retrieval of an Inferior Vena Cava Filter During Pregnancy Because of Filter Tilt: Report of Two Cases”

I read with interest the recently reported cases of failed retrieval of suprarenally placed inferior vena cava (IVC) filters in two pregnant patients by McConville et al. [1]. We would like to add our experience with a similar case of failed retrieval at our institution recently. A 27-year-old prima gravid woman was referred for removal of a Gunther Tulip filter which had been inserted at another institution 10 weeks earlier at 30 weeks of gestation. The patient had been diagnosed with extensive left-sided iliofemoral deep venous thrombosis and commenced on anticoagulation with low molecular weight heparin. Soon afterward she developed pleuritic chest pain and shortness of breath. The patient refused CT pulmonary angiography because of concerns about radiation exposure and was therefore treated empirically as having incurred a pulmonary embolus. A Gunther Tulip filter was subsequently inserted and positioned in the suprarenal IVC. The patient had a difficult labor 10 weeks later, necessitating a forceps-assisted delivery. She was referred 3 days postpartum for removal of the filter (73 days postinsertion). Preremoval vena cavogram demonstrated a suprarenal position, with no tilt of the cone or malposition of the filter struts. A retrieval set was inserted from the right internal jugular, and the retrieval hook successfully snared. However, it was not possible to fully collapse the struts (Fig. 1), despite applying rotational and torqueing force to the filter using the retrieval system sheath. The patient was complaining of right-sided upper abdominal pain, so no other aggressive maneuvers for removal were applied, as risk of caval rupture or tear was deemed too significant. There is scant published evidence of successful retrieval of temporary suprarenal IVC filters in pregnancy. The sole series, published by Kawamata et al. [2], involved successful retrieval of Neuhaus Protect (Toray Medical, Tokyo) or Antheor (Boston Scientific, Watertown, MA,

Prophylactic Inferior Vena Cava Filters: Do They Make a Difference in Trauma Patients?

Inferior vena cava filters (IVCF) are used in trauma patients to reduce the incidence of pulmonary embolism (PE). This study investigates the efficacy of prophylactic IVCF (PIVCF) placement from implantation through outpatient follow-up. Data were prospectively collected on PIVCF placed in trauma patients > or =18-years old from 2004 to 2006. Exclusion criteria include therapeutic IVCF, major burns, deviated from a modified EAST protocol, and deaths. Data were collected on age, gender, Injury Severity Score (ISS), filter type, total implant days, PE, deep venous thrombosis (DVT), and filter-related complications. p < 0.05*, chi square test, mean +/- SD. Of 4,936 patients, 280 had an IVCF with 244 meeting inclusion criteria. Study group demographics: 63.5% men; 98.8% blunt; mean age 43.8 +/- 20.3; ISS 26.7 +/- 12.8. There were 176 of 244 (72.1%) patients who met traditional EAST guidelines for PIVCF. PIVCF increased significantly from 29 in 2004 to 127 in 2006 with no difference in the PE rate (0.7% to 0.4%). There were 4 PEs (1.6%) on postprocedure days 7, 14, 18, and 23. Five technical complications occurred: two filter fractures, two caudal migrations, and one filter tilt. A total of 140 retrievable filters had the opportunity for outpatient follow-up for 18 months with 58.6% removed, 15.7% declared permanent, 12.1% lost to follow-up, and 13.6% still considered potential removal candidates. Days to implant: 0 to 32; 3.89 +/- 4.79. Implant days: 15 to 838; mean 231 +/- 162. PIVCF increased significantly without impacting the overall PE rate. There was a 1.6% PE rate among PIVCF, high retrieval rate (59%), low complication rate (0.1%), and satisfactory compliance with traditional EAST guidelines.

Failed Retrieval of an Inferior Vena Cava Filter During Pregnancy Because of Filter Tilt: Report of Two Cases

Thromboembolic disease during pregnancy is an important cause of obstetric morbidity and mortality. Pregnant patients with venous thromboembolism are usually managed by conventional anticoagulation. However, this must be discontinued during vaginal or caesarian delivery to avoid haemorrhage and to reduce the risk of possible epidural haematoma. Retrievable inferior vena cava filters (IVCFs) offer protection against pulmonary embolism during this high-risk period, when anticoagulation is discontinued, while avoiding potential long-term sequelae of a permanent IVCF. Here we report two patients who presented in the third trimester of pregnancy with floating ileofemoral deep vein thrombosis. Both patients were initially treated with standard anticoagulation; however, shortly before delivery both patients had a retrievable IVCF placed in a suprarenal position. In both patients, retrieval failed at 28 days after insertion because of filter tilt. The timing and mechanism of filter tilt remains uncertain. We believe that a number of factors could have been involved, including change in the anatomic configuration with lateral displacement of the IVCF as a result of the gravid uterus as well as forceful uterine contractions during labour, which modified the shape and diameter of the IVC. We showed that failure to retrieve the IVCF has had considerable implications for the two young patients regarding long-term anticoagulation and have highlighted the need for further clinical trials regarding the safe use of retrievable IVCFs during pregnancy.

Factors Associated with Failed Retrieval of the Günther Tulip Inferior Vena Cava Filter

To identify potential factors associated with failed retrieval of the Günther Tulip inferior vena cava (IVC) filter. A retrospective review was performed of patients who underwent placement of the Günther Tulip filter with at least one attempt at filter retrieval over a 3-year period. Patient demographics, filter dwell time, filter angulation, and filter leg protrusion were analyzed. A total of 188 patients were included in the study. Primary retrieval success was achieved in 166 patients (88.3%), for an overall retrieval success rate of 94.2%. The overall mean dwell time was 63 days, whereas the mean dwell time in cases of retrieval failure was 95.4 days. A total of seven filters were in place for longer than 6 months, four of which were successfully retrieved. The degree of filter tilt was not found to be significantly related to retrieval success (P = .36), even though filter angulation was commonly cited as a reason for retrieval failure. On venography, 90.9% of filters that could not be retrieved showed leg protrusion beyond the lumen of the IVC. Finally, increasing patient age also correlated with retrieval failure (P = .01). Prolonged dwell time and increasing patient age are associated with failed filter retrieval. However, even filters in place for extended periods can be safely removed.

Analysis of Tilt of the Günther Tulip Filter

To determine the frequency, dimensions, predictors, and sequelae of Günther Tulip filter (GTF) tilt measured at the time of intended retrieval. Retrospective review of all medical records and posteroanterior cavograms of 175 patients who underwent both placement and retrieval of the GTF between August 2003 and July 2007 was performed to assess the frequency, dimensions, predictors, and sequelae of tilt. Tilt occurred at the first retrieval attempt in 159 of the 175 patients (91%). The average degree of tilt was 7.1 degrees (range, 0 degrees-30 degrees), with 87 of the 159 filters with tilt (55%) having a rightward tilt. Compared with the femoral approach, filters placed with a jugular approach demonstrated 4.2 degrees (range of the standard deviation, 3.1 degrees-5.3 degrees) greater tilt at the first retrieval attempt (95% confidence interval=2.6 degrees, 5.7 degrees; P<.001, two-sided Student t test), a greater frequency of tilt of at least 14 degrees (P=.002, two-sided Fisher exact test), and greater rightward tilt predominance (P=.046, one-sided Fisher exact test). Tilt magnitude at the first retrieval attempt correlated positively with the inferior vena cava diameter 40 mm caudal to the renal vein confluence (R=.183, P=.018, Pearson correlation). Within its limitations, this study detected no new cases of pulmonary embolism, caval perforation, or GTF migration. The success rates at the first attempt at retrieval and the cumulative GTF retrieval success rates were 93% (176 of 190 filters) and 97% (181 of 190 filters), respectively. All 29 GTFs with tilt of at least 14 degrees were placed and successfully retrieved by means of a jugular approach with minimal clinical and technical sequelae. Frequent GTF tilt detected at the first retrieval attempt can reach at least 14 degrees and is associated with minimal sequelae. Insertion approach and caval diameter are significant factors in GTF tilt.

Management of Severe Vena Cava Filter Tilting: Experience with Bard G-2 Filters

The purpose of this article is to discuss the occurrence of abdominal pain associated with severe tilting of the Bard G-2 inferior vena cava filters. Potential reasons for the occurrence of tilting and management of tilting of the filters are discussed.

Safety, feasibility, and outcome of retrievable vena cava filters in high-risk surgical patients

Retrievable vena cava filters (rVCFs) are being used frequently in the perioperative setting for preventing pulmonary embolism. The indications and safety profile for placement of preoperative retrievable vena cava filters (rVCFs) remains undefined, however. This study sought to determine the safety, feasibility, and outcome of rVCFs in bariatric surgery patients, who are known as a high-risk population for periprocedural deep vein thrombus (DVT) or pulmonary embolus, or both. Between June 1, 2004, and October 1, 2005, protocols were developed and implemented at a tertiary referral hospital for placement of rVCFs in 59 consecutive high-risk patients undergoing laparoscopic gastric bypass or duodenal switch if they met any of the following criteria: body mass index >55 kg/m(2), hypercoagulable state, severe immobility, venous stasis, or previous history of DVT or pulmonary embolus. Using both Site-Rite (Bard Access Systems, Salt Lake City, Utah) ultrasound and fluoroscopy, Günther Tulip (Cook, Inc., Bloomington, Ind) rVCFs were placed immediately after general anesthesia, just preceding the bariatric procedure. The internal jugular vein was the preferred approach, followed by the femoral vein. Retrieval was performed after the fourth postoperative week. During a 16-month period, 60 rVCFs were placed in 61 attempts, 57 through the internal jugular vein and three through the femoral vein. Six patients refused the retrieval attempt. Of the remaining 54 rVCFs, the primary retrieval success was 90% (49/54), with all failures due to severe filter tilt. The secondary retrieval success was 100% (3/3). The two remaining patients refused secondary retrieval attempt. The mean +/- standard deviation dwell time of the rVCFs was 63 +/- 30 days. No procedure complications occurred in placement or retrieval. One patient developed a clinical pulmonary embolism with the filter in place while not receiving postoperative anticoagulation. No patients died. The mean body mass index of the patients was 61 +/- 10 kg/m(2). Placement and retrieval of retrievable vena cava filters in high-risk bariatric surgery patients is safe, feasible, and offers potential clinical benefit to patients requiring short-term protection from pulmonary embolism.

Gunther Tulip Retrievable Inferior Vena Caval Filters: Indications, Efficacy, Retrieval, and Complications

We evaluated the Gunther Tulip (GT) retrievable inferior vena cava (IVC) filter with regard to indications, filtration efficacy, complications, retrieval window, and use of anticoagulation. A retrospective study was performed of 147 patients (64 men, 83 women; mean age 58.8 years) who underwent retrievable GT filter insertion between 2001 and 2005. The indications for placement included a diagnosis of pulmonary embolism or deep venous thrombosis with a contraindication to anticoagulation (n = 68), pulmonary embolism or deep venous thrombosis while on anticoagulation (n = 49), prophylactic filter placement for high-risk surgical patients with a past history of pulmonary embolism or deep venous thrombosis (n = 20), and a high risk of pulmonary embolism or deep venous thrombosis (n = 10). Forty-nine of the 147 patients did not receive anticoagulation (33.7%) while 96 of 147 patients did, 82 of these receiving warfarin (56.5%), 11 receiving low-molecular weight heparins (7.58%), and 3 receiving antiplatelet agents alone (2.06%). Filter placement was successful in 147 patients (100%). Two patients had two filters inserted. Of the 147 patients, filter deployment was on a permanent basis in 102 and with an intention to retrieve in 45 patients. There were 36 (80%) successful retrievals and 9 (20%) failed retrievals. The mean time to retrieval was 33.6 days. The reasons for failed retrieval included filter struts tightly adherent to the IVC wall (5/9), extreme filter tilt (2/9), and extensive filter thrombus (2/9). Complications included pneumothorax (n = 4), failure of filter expansion (n = 1), and breakthrough pulmonary embolism (n = 1). No IVC thrombotic episodes were recorded. The Gunther Tulip retrievable filter can be used as a permanent or a retrievable filter. It is safe and efficacious. GT filters can be safely retrieved at a mean time interval of 33.6 days. The newly developed Celect filter may extend the retrieval interval.

Retrievable Inferior Vena Cava Filters: Initial Clinical Results

Anticoagulation is the accepted therapy for patients with thromboembolic disease. When contraindications to anticoagulant therapy are present, however, interruption of the inferior vena cava (IVC) may prevent pulmonary embolism (PE). The objective of this study was to report our early technical and clinical results with retrievable IVC filters (IVCFs) for the prevention of PE. One hundred and twenty-seven multitrauma patients between December 1, 2002, and December 31, 2004, underwent placement of Gunther-Tulip (n = 49), Recovery (n = 41), or OptEase (n = 37) retrievable IVCFs under real-time intravascular ultrasound (IVUS) guidance. All patients had abdominal X-rays to verify filter location. Prior to IVCF retrieval, all patients underwent femoral vein color flow ultrasonography to rule out deep vein thrombosis (DVT) and vena-cavography to assess the IVCF for trapped emboli, filter tilt, or retrained thrombus. Thirty-nine patients died of their injuries; no deaths were related to IVCF placement. One PE occurred during follow-up after filter retrieval, and two femoral vein insertion-site DVTs occurred. One hundred twenty (94.4%) of IVCFs were placed without complication at the L2-3 level, as verified by abdominal X-rays. Filter-related complications included three groin hematomas (2.9%) and three IVCFs misplaced in the right iliac vein early in our experience (2.3%); these filters were uneventfully retrieved and replaced in the IVC within 24 hr. Sixty-six patients underwent uneventful retrieval of IVCFs after DVT or PE anticoagulation prophylaxis was initiated. Forty-five IVCFs were not removed: 41 due to contraindications due to anticoagulation and four because of trapped thrombus within the filter. The role of retrievable IVCFs continues to evolve, but in this study of 127 patients, prophylactic temporary IVCF placement was simple and safe, prevented fatal PE, and served as an effective "bridge" to anticoagulation. Further investigation of this bedside IVUS technique and the role of temporary IVCFs in different patient populations is warranted.

A Modified Technique to Minimize Filter Tilting during Deployment of the Günther Tulip Filter: In Vitro Study

With an in vitro model of the inferior vena cava, it was demonstrated that slight tension on the introducer during quick release of the jugular Günther Tulip filter led to less tilting of the filter compared with the technique recommended by the manufacturer. This technique may be useful to minimize significant filter tilting that may be associated with decreased filtration efficiency, and difficulty or impossibility of future filter retrieval.