Celect Filters Research Articles

Correlation of intravascular ultrasound and computed tomography scan measurements for placement of intravascular ultrasound-guided inferior vena cava filters

The single puncture intravascular ultrasound (IVUS)-guided bedside placement of inferior vena cava (IVC) filters has been shown to be an effective technique. The major disadvantage of this procedure is a steep learning curve that can lead to an increased risk of filter malposition. In an effort to increase the safety and efficacy of IVUS-guided bedside IVC filter placement, we proposed that preoperative planning could reduce the incidence of IVUS-guided filter malpositions. As a first step, we examined the correlation between preoperative abdominal computed tomography (CT) scan measurements and intraprocedural IVUS derived measurements of vena cava anatomy and its surrounding structures. As a second step, we attempted to determine the safety of this protocol by assessing the incidence of malposition. A retrospective review of prospectively collected data was performed on all patients receiving bedside IVUS-guided filters from July 1, 2010 to August 31, 2011. Measurements of the IVC length from the atrial-IVC junction to the midportion of the crossing right renal artery, the lowest renal vein, and iliac vein confluence were obtained prior to IVC filter placement by both CT-based measurement, as well as intraprocedural IVUS pullback lengths. Regression analysis (significant for P < .05) was used to determine the correlation between these imaging modalities. Forty-six patients had adequate CT scans available to perform the analysis and were candidates for bedside IVUS-guided IVC filter placement. All IVUS-guided filters were placed using a single puncture technique with the Cook Celect Filter. This study found there was a close correlation between IVUS and CT derived measurements of the right atrium to right renal artery distance, lowest renal vein distance, and iliac confluence distance. In addition, we found that the IVUS distances from the atrial-IVC junction to the right renal artery and lowest renal vein were statistically similar. Nine patients had 10 vascular anatomic variations, all identified by both IVUS and CT. There were no complications or malpositions of IVC filters using this protocol. These data suggest that IVUS pullback measurements from the right atrium used in combination with preprocedure CT derived measurements of the distance from the right atrium to the lowest renal vein and iliac vein confluence provide an accurate roadmap for the placement of bedside IVC filters under IVUS guidance. We provide a method for organizing this information in a preplanning document to aid this procedure. We suggest this easily employed technique be more fully utilized to help decrease the incidence of malpositioned filters using single puncture IVUS guidance.

Complications of Celect, Günther Tulip, and Greenfield Inferior Vena Cava Filters on CT Follow-up: A Single-Institution Experience

PurposeTo evaluate and compare the rates of complications on follow-up computed tomography (CT) studies of patients with Celect, Günther Tulip, and Greenfield inferior vena cava (IVC) filters. Materials and MethodsRetrospective review of CT studies obtained 0–1,987 days after infrarenal placement of an IVC filter identified 255 Celect, 160 Tulip, and 50 Greenfield filters. Follow-up CT studies were independently evaluated by two observers for IVC perforation, contact with adjacent organs, and filter fracture. Multivariate analysis was performed to identify factors associated with higher rates of IVC perforation, including age, IVC diameter, sex, and history of malignancy. ResultsIVC perforation was observed in 126 of 255 Celect filters (49%) with a mean follow-up of 277 days, 69 of 160 Tulip filters (43%) with a mean follow-up of 437 days, and one of 50 Greenfield filters (2%) with a mean follow-up of 286 days. A significantly higher IVC perforation rate was observed in women (45.5%) compared with men (30.8%; P = .002) and in patients with a history of malignancy (43.7%) compared with patients with no history of malignancy (29.9%; P < .001). Filter fracture was rare, observed in two of 255 Celect filters (0.8%), one of 160 Tulip filters (0.6%), and none of 50 Greenfield filters. ConclusionsNo significant difference was observed in IVC perforation rate between Celect and Tulip filters. Greenfield filters had a significantly lower rate of IVC perforation than Celect and Tulip filters. Higher IVC perforation rates were observed in women and patients with a history of malignancy.

Fracture and Migration of Celect Inferior Vena Cava Filters: A Retrospective Review of 741 Consecutive Implantations

PurposeTo determine the incidence of fracture and migration of the Celect inferior vena cava (IVC) filter at a single tertiary-care center. Materials and MethodsImages obtained after placement of Celect IVC filters between August 2007 and January 2013 were retrospectively reviewed for evidence of device fracture and migration. The probability of filter fracture at 6 and 12 months after filter placement was estimated, and a 95% upper confidence bound was constructed. ResultsA total of 741 consecutive Celect filters were placed, and the following studies were subsequently evaluated: 301 abdominal radiographs, 282 abdominal computed tomography (CT) scans, 154 cavagrams, 19 lumbar spine radiographs, 462 chest radiographs, 108 chest CT scans, and 31 pelvic radiographs. The mean imaging follow-up interval was 5.78 months ± 8.80 (range, 0.01–56.03 mo). There was no filter fracture or en-bloc migration outside the IVC. Upper 95% confidence bounds for the probability of fracture were 1.8% at 6 months and 4.3% at 12 months. Intracaval filter migration of more than 2 cm (mean, 2.43 ± 0.12 cm; range, –2.54 to 2.99 cm) was seen in 3.9% of patients (21 of 534; 12 cranial and nine caudal). ConclusionsNo fracture of a Celect filter was observed in this large cohort over a relatively short follow-up interval. The results also suggest that the Celect filter has an adequate securing mechanism to prevent distant en-bloc or significant intracaval migration.

8:48 AM Abstract No. 181 - A prospective comparison of retrievability: celect versus option filter

Purpose Potentially retrievable design technology has significantly increased the utilization of IVC filters in the US. In this study, we aimed to compare the ease of retrievability of two potentially retrievable IVC filter (pfIVCF) devices. We hypothesize that the retrievability for the Celect (Cook Inc, Bloomington, IN) and Option (Rex Medical, Conshohocken, PA) devices is equivalent. Materials and Methods In this prospective, IRB-approved study, Celect and Option filters were deployed for generally accepted indications. Fluoroscopy time, presence of significant filter tilt, use of adjunctive retrieval techniques, and strut perforation of the IVC were each recorded at the time of retrieval. Fisher’s exact test and Mann-Whitney-Wilcoxon test were used for statistical analysis, with the null hypothesis rejected at p Results Over a 30 month period, 88 Celect and 83 Option filters were deployed. 53.4% (n = 47) of Celect patients and 74.7%(n = 62) of Option patients presented for filter retrieval after an average of 2.26 months (range 0.3-7.6) and 1.98 months (range 0.47-9.13) respectively. No patients were lost to follow up. Retrieval failure rates were Celect 2.3% vs Option 6.5% (p = 0.697). Median fluoroscopy retrieval times were Celect 4.3 minutes (SD 14.66) vs Option 6.45 minutes (SD 12.37) (p = 0.012). Use of adjunctive retrieval techniques was Celect 6.7% vs Option 19% (p = 0.087). Incidence of significant tilting was Celect 13.3% vs Option 19% (p = 0.594). Incidence of strut perforation was Celect 44% vs Option 0% (p Conclusion Overall retrieval rates for the Celect and Option filters were equivalent. However, retrieval of the Option filter required a statistically significant increased amount of fluoroscopy time compared with the Celect filter. There was a trend toward more use of adjunctive retrieval techniques for the Option filter. The Celect filter had a statistically significantly higher rate of strut perforation.

8:00 AM Abstract No. 175 - Retrospective review of 143 celect IVC filter retrievals: experience at a single institution

Purpose To retrospectively evaluate the safety and retrievability of the Celect IVC filter. Materials and Methods All patients undergoing Celect filter placement and retrieval between 2007 and 2012 were assessed for complications and retrievability. Results Of 690 patients who had Celect filter placement, 143 presented for removal. The indwelling time in these patients was 176.2 ± 150.3 days (range, 2-1413 d). A total of 125 filters (87.4%) were removed; 18 filters were left in situ for the following reasons: filter embedment (7), caval occlusion (3), retained thrombus (3), large floating thrombus in IVC (4), or tilt > 15° (1). With filters in place, 6 patients developed new pulmonary embolism and 2 others presented with severe abdominal pain. The available 135 pairs of placement and removal cavagrams suggested limb penetration in 112 cases (86.1%); intracaval migration > 2 cm in 5; secondary tilt > 15° in 8; filter deformity in 10; retained thrombus within filters in 13; and IVC occlusion in 3. Among 52 available CT scans, 11 cases (21%) demonstrated asymptomatic limb penetration to the duodenum (6), aortic wall (3), kidney (1) and liver (1). No filter fracture was found. Conclusion This study showed a high penetration rate for Celect IVC filters, including penetrations that were symptomatic or involved adjacent structures. Penetration appears to correlate with indwelling time, suggesting that the filter should be removed as soon as PE protection is no longer indicated. Although most of the filters were removed, 5.6% of retrievals were unsuccessful because of technical failure.

Retrospective Review of 120 Celect Inferior Vena Cava Filter Retrievals: Experience at a Single Institution

PurposeTo evaluate retrospectively the safety and retrievability of the Celect IVC filter. Materials and MethodsAll patients undergoing Celect filter placement and retrieval during the period 2007–2012 were assessed for complications and retrievability. ResultsOf 620 patients who underwent Celect filter placement, 120 presented for removal. The indwelling time in these patients was 158.1 days±103.0 (range, 2–518 d). There were 106 filters (88.3%) removed; 14 filters were left in situ for the following reasons: filter embedment (n=6), caval occlusion (n=3), retained thrombus (n=2), large floating thrombus in IVC (n=2), or tilt >15° (n=1). With filters in place, five patients developed new pulmonary embolism (PE), and two others presented with severe abdominal pain. The available 115 pairs of placement and removal cavagrams suggested limb penetration in 99 cases (86.1%), intracaval migration >2 cm in 5, secondary tilt >15° in 8, filter deformity in 10, retained thrombus within filters in 12, and IVC occlusion in 3. Among 38 available computed tomography (CT) scans, 9 scans (24%) showed asymptomatic limb penetration to the duodenum (n=6), aortic wall (n=2), or kidney (n=1). No filter fracture was found. ConclusionsThis study showed a high penetration rate for Celect IVC filters, including penetrations that were symptomatic or involved adjacent structures. Penetration appears to correlate with indwelling time, suggesting that the filter should be removed as soon as PE protection is no longer indicated. Although most of the filters were removed, 5.8% of retrievals were unsuccessful because of technical failure.

Laparoscopic Demonstration of Vena Cava Wall Penetration by Inferior Vena Cava Filters in an Ovine Model

Purpose To verify the penetration of struts and hooks of two inferior vena cava (IVC) filters (Günther tulip retrievable filter [GTF] and Celect filter) through the vena cava wall and to assess local or systemic complications resulting from this penetration. Materials and Methods Eight IVC filters were placed in the IVC of four ewes for 30 days (1 GTF and 1 Celect filter in each ewe). Angiographic and laparoscopic examinations of the animals were performed to demonstrate the penetration through the vena cava wall, and the filters were removed under laparoscopic control. Specimens were extracted for anatomicopathological and histologic examination. Results Two-projection cavography showed a filter leg seemingly out of the vena cava in 19 of 32 legs (59.3%). Laparoscopy showed 7 real penetrating legs (5 Celect filters and 2 GTFs) out of the 14 legs that could be identified by laparoscopy owing to technique limitations. Neither laparoscopy nor necropsy showed any sign of wall hemorrhage or other injuries. Histologic examination showed intimal remodeling and slight thickening of adventitial tissue around filter legs. Conclusions GTFs and Celect filters can produce a real penetration 1 month after implantation. This penetration did not lead to any complications in the IVC or surrounding tissues and did not compromise the subject's health in any of the studied cases.

Modeling Blood Flow in a Tilted Inferior Vena Cava Filter: Does Tilt Adversely Affect Hemodynamics?

Purpose Filter tilt is often seen with conical filters and adversely affects retrievability and clot trapping efficiency. In addition, tilt may also alter flow dynamics. This study uses computational fluid dynamics to evaluate flow past an unoccluded and partially occluded Celect inferior vena cava filter (Cook, Bloomington, Indiana). In particular, the hemodynamic response to thrombus volume and filter tilt is examined, and the results are compared with flow conditions known to be thrombogenic. Materials and Methods Computer models of an upright and tilted Celect filter are constructed using high-resolution digital photographs and methods of computer-aided design. The three-dimensional models are placed inside a model cava, and steady-state flow past unoccluded and partially occluded filters is computed. Results The volume of stagnant and recirculating flow increases with thrombus volume. In addition, as filter tilt increases, the cava wall in the direction of filter tilt is subjected to low-velocity flow and gives rise to regions of low wall shear stress. Conclusions Flow conditions caused by the tilted Celect filter may elevate the risk of intra/perifilter thrombosis and facilitate vascular remodeling. This latter condition may increase the potential for incorporation of the hook of the filter into the vena cava wall, thereby complicating filter retrieval. These findings also suggest that further long-term clinical follow-up with conical filters should be pursued with a specific evaluation of tilt as a factor of intrafilter thrombus and thrombosis.

Toward an Optimal Position for Inferior Vena Cava Filters: Computational Modeling of the Impact of Renal Vein Inflow with Celect and TrapEase Filters

Toward an Optimal Position for Inferior Vena Cava Filters: Computational Modeling of the Impact of Renal Vein Inflow with Celect and TrapEase Filters

Surgical Management of Inferior Vena Cava Strut Penetration Causing Hydronephrosis: Case Report

We present a case of penetration of inferior vena cava (IVC) by primary struts of Cook Celect filter and impingement on right ureter, causing symptomatic hydronephrosis and hydroureter, which was managed surgically by ureterolysis, mobilization of the ureter by retroperitoneal approach, excision of the filter strut, and omental wrap around the ureter.

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.

Günther Tulip and Celect IVC Filters in Multiple-Trauma Patients

To evaluate results with the retrievable Günther Tulip (GT) and Celect inferior vena cava filters (IVCFs) placed at the intensive care unit (ICU) bedside under "real-time" intravascular ultrasound (IVUS) guidance in multiple-trauma patients. Between December 2004 and December 2008, 187 multiple-trauma patients (109 men; mean age 44+/-2 years, range 17-71) with contraindications to low-dose anticoagulation therapy or sequential compression devices had Günther Tulip (n = 97) or Celect (n = 90) retrievable IVCFs placed under real-time IVUS guidance. Günther Tulip filters were inserted using a "double-puncture" technique. The Celect IVCFs were placed with a simplified single-puncture technique in which the filter introducer sheath was advanced until the radiopaque tip "covered" the IVUS image of the renal vein, indicating that the filter sheath was in position for filter deployment. The 2 filter groups were compared on the endpoints of technical implantation success, retrievability, prevention of PE, and procedure-related deep vein thrombosis (DVT). As verified by abdominal radiography, 93.1% (174/187) of IVCFs were placed without complications; 6 IVCFs (all GT; p = 0.03 versus Celect) were misplaced in the iliac vein but uneventfully retrieved and replaced in the IVC within 24 hours. Two insertion site femoral vein DVTs (both in the dual puncture group; p>0.2) and 5 groin hematomas occurred during follow-up. GT filters were in place a mean of 107 days and Celect 97 days. In this time, 2 pulmonary embolisms occurred (1 in each group; p>0.2). Of the 115 filters scheduled for retrieval (50 Günther Tulip, 65 Celect), 33 (23 Günther Tulip, 10 Celect) could not be retrieved (p = 0.0004). Vena cavography identified filter tilting (>20 degrees ) in 21 cases (15 GT, 6 Celect), while 12 filters (8 GT, 4 Celect) had extended indwell times (mean 187 days) and excessive tissue ingrowth covering the retrieval hook. Subjectively, the Celect filters were clinically "easier" to retrieve; they also had fewer cases of significant tilt (>20%) than the GT filters, but the difference was not statistically significant. GT and Celect IVCFs placed at the ICU bedside under IVUS guidance in multiple-trauma patients was simple, safe, and avoided transporting critically ill patients out of the ICU. Further investigation of the single sheath IVUS technique and the role of retrievable IVCFs in multi-trauma patients is warranted.

Initial experience in 115 patients with the retrievable Cook Celect vena cava filter

The aim of this study was to evaluate our experience with the retrievable Cook Celect inferior vena cava (IVC) filter (William Cook, Europe) with regard to insertion, efficiency, ease of retrieval, and any associated complications. A retrospective review was performed of 115 patients (41 female, 74 male, mean age 47.97 years) who underwent Cook Celect IVC filter insertion between December 2005 and October 2007. Filter insertion was successful in all patients. Of the 115 filters inserted, 57 have been successfully retrieved (49.6%) to date. The successful retrieval rate from attempted retrieval was 93.4%. The mean dwell time of successfully retrieved filters was 114.9 days (range 14-267 days). Failed retrievals were due to a thrombosed vena cava (n = 1) and endothelialisation of the filter (n = 3). In the failed retrieval group the mean implantation time was 142 days (range 78-211 days). While this is the first retrospective clinical study on the Cook Celect filter, results to date are promising. We demonstrated an efficacious filter with a high successful retrieval rate of 93.4% and a low complication rate. The filter was assessed with extended dwell times (range 14-267 days). Failed retrieval secondary to hook endothelialisation continues to be an issue with this filter. We recognize that a limitation of our study was the lack of systematic follow-up for clinically silent complications. Further studies to evaluate longer term outcomes and effectiveness of this filter are warranted.

Deployment Performance and Retrievability of the Cook Celect Vena Cava Filter

To test the safety, performance, and retrievability of the Cook Celect vena cava filter. Twenty female or castrated male sheep were implanted with two Celect filters in series, in the inferior vena cava. The animals were divided into five groups of four animals according to day of filter retrieval. Filter retrieval occurred at approximately 30, 60, 90, 180, and 360 days after implantation. At each time point, two sheep underwent retrieval attempts of both the cranial and caudal filters. These animals were recovered for 30 days, at which time healing was assessed. In two additional sheep at each time point, retrieval of only the cranial filter was attempted and the caudal filter was left in situ. These sheep were euthanized after retrieval, and the segment of vena cava encompassing the sites of both the retrieved filter and the filter left in situ was excised for gross and histopathologic analysis. Retrieval attempts occurred at 34, 62, 90, 188, and 393 days after implantation. All retrievals were successful (30 of 30). Tilt was detected in eight filters at implantation; six had self-centered before retrieval. At retrieval, no filter migration or deformation was reported. All filters were retrieved with acceptable levels of force. At each time point, there was evidence of mild intimal hyperplasia at the filter anchoring sites and no evidence of vena cava injury. The Celect vena cava filter was safely used as a retrievable filter for up to 393 days in an ovine model.

Assessment of Snared-Loop Technique When Standard Retrieval of Inferior Vena Cava Filters Fails

To identify the success and complications related to a variant technique used to retrieve inferior vena cava filters when simple snare approach has failed. A retrospective review of all Cook Günther Tulip filters and Cook Celect filters retrieved between July 2006 and February 2008 was performed. During this period, 130 filter retrievals were attempted. In 33 cases, the standard retrieval technique failed. Retrieval was subsequently attempted with our modified retrieval technique. The retrieval was successful in 23 cases (mean dwell time, 171.84 days; range, 5-505 days) and unsuccessful in 10 cases (mean dwell time, 162.2 days; range, 94-360 days). Our filter retrievability rates increased from 74.6% with the standard retrieval method to 92.3% when the snared-loop technique was used. Unsuccessful retrieval was due to significant endothelialization (n = 9) and caval penetration by the filter (n = 1). A single complication occurred in the group, in a patient developing pulmonary emboli after attempted retrieval. The technique we describe increased the retrievability of the two filters studied. Hook endothelialization is the main factor resulting in failed retrieval and continues to be a limitation with these filters.

Long-Term Retrieval of Modified G??nther Tulip Vena Cava Filters

We modified the Günther Tulip Filter to allow long-term retrieval and tested this modified filter design in an animal experiment. Fourteen modified Günther Tulip Filters (Celect filter) were inserted percutaneously into the inferior venae cavae of 7 domestic adult sheep (2 filters per animal). Before removal, 3 months after filter placement, cavography was performed and the filters were removed. Subsequently, cavography was obtained to check for any signs of bleeding. All venae cavae were prepared, removed, and macroscopically examined for bleeding. Filter placement was easy and successfully performed in all cases. No thrombi were detected inside the filters. All cases showed some narrowing of the vena cava at the level, where the filter legs were connected with the vessel wall. Neither cavograms after filter removal nor macroscopic examinations of the perivascular vena cava tissue showed any significant bleeding. The modified Günther Tulip Filter allowed for successful and uncomplicated filter removal up to 3 months after placement.

In Vitro Evaluation of Optionally Retrievable and Permanent IVC Filters

To systematically evaluate different optionally retrievable and permanent inferior vena cava (IVC)-filters with respect to their capture rates. Seven optionally retrievable and permanent IVC filters were tested in an in vitro flow model with a tube size of 22 mm in horizontal and vertical positions. To analyze the capture efficiency the IVC filters were implanted in concentric and eccentric positions and subsequently exposed to single and multiple blood clots of different sizes (3x5, 3x10, 5x10, 5x20, 7x20, 10x24 mm). Capture rates and pressure changes were measured and compared between the different IVC filters. There were significant differences between the tested IVC filters. In general, the capture rate improved with increasing clot size (P<0.0001). In the single-clot exposure the highest mean capture rate was achieved with the Celect filter (90.4%+/-15.7%), whereas the Günther Tulip filter achieved best results in the multi-clot exposure (76.7%+/-12.5%). Capture rates differed significantly between the various IVC filters (single-clot: P<0.0001; multi-clot: P=0.0016). The position (horizontal or vertical) did not show a significant influence, whereas capture rates significantly decreased in the multi-clot test with eccentric filter positions (P=0.0299). In this study optionally retrievable IVC filters were more efficient than the tested permanent IVC filters (single-clot: P<0.0001; multi-clot: P=0.0002). Optionally retrievable IVC filters are efficient. Clot size, IVC filter type, and position significantly influence capture rate. Deliberate selection of the most efficient IVC filter and concentric positioning are important to ensure optimal results.

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.

New Optional IVC Filter for Percutaneous Retrieval - In Vitro Evaluation of Embolus Capturing Efficiency

In-vitro evaluation of a new caval filter (Cook Celect Filter) developed for delayed percutaneous retrieval in comparison to the Gunther Tulip filter. The new Celect filter is constructed on the basis of the Tulip filter and consists of 4 primary anchoring legs and additional 8 thinner secondary wires to stabilize the filter and to guarantee adequate filtering efficiency. The filtering wires are of the same amount and equal distribution as the filtering wires of the Tulip filter. The secondary wires are arranged in such a way that percutaneous filter retrieval should be possible even if the wires are incorporated into the caval wall. In a flow model (tube size ø15-, ø22- and ø30 mm), the filter was exposed to single and multiple emboli (blood clots) of different sizes (3 x 5, 3 x 10, 5 x 10, 3 x 20, 5 x 20, 7 x 10, 7 x 20 to 10 x 24 mm) to analyse the embolus capturing efficiency under different conditions including eccentric and concentric, horizontal and vertical positions in comparison to the Tulip filter. All testing was carried out in SPSS analytic software; statistical significance was assumed for p-values < 0.05. The in-vitro embolus capturing efficiency of the Celect filter proved to be equivalent to the Tulip filter. In the single-embolus test, 91.6 % of the clots were captured by the Celect filter and 87.2 % by the Tulip filter (p = 0.042). Large clots ranging from 7 x 10 to 10 x 24 mm were captured in all cases, whereas the capture rates for the 3 x 5-mm and 3 x 10-mm clots were lower. The filters captured significantly more clots in the concentric than in the eccentric location. There was no significant difference between the overall capture rates of the two filters in the multi-clot test (72.2 % vs. 75.1 %), which showed deterioration of filter function during multiple clot exposure. With the 15-mm tube, the Celect filter had a significantly higher capture rate than the Tulip filter, whereas it was lower with the ø30-mm tube. There was no significant difference between the filters in a ø22-mm tube. The pressure gradient across the filters when exposed to blood clots ranged from 4.9 - 7.4 mm Hg for the Celect filter and 5.7 - 6.8 mm Hg for the Tulip filter in the single-embolus testing. There was no significant difference in the multi-clot tests. The new Celect filter showed similar in-vitro capture properties as the Gunther Tulip filter and deserves further in-vivo testing.