Vena cavography with CO(2) versus with iodinated contrast material for inferior vena cava filter placement: a prospective evaluation

PURPOSE: To determine whether carbon dioxide (CO(2)) vena cavography can safely guide the placement of inferior vena cava (IVC) filters. MATERIALS AND METHODS: One hundred nineteen patients were prospectively enrolled in this study. CO(2 )cavograms were obtained and evaluated for IVC diameter, location of renal veins, and presence of thrombus and venous anomalies. If CO(2 )cavography was judged to be adequate, an IVC filter was deployed. After filter placement, cavography was performed with iodinated contrast material; these images were compared with the CO(2) cavograms. RESULTS: Two patients experienced mild side effects related to venous CO(2) injection. Comparison of cavograms obtained with CO(2) and iodinated contrast-enhanced material showed the caval size to be within 3 mm in all 119 patients. In 116 patients (97.5%), CO(2) cavography was judged to be adequate, and in 115 patients, filters were placed. In three (2.5%) patients, it was necessary to perform iodinated contrast-enhanced cavography before filter deployment. All six cases of venous anomaly and 11 (78.6%) of 14 cases of thrombosis were clearly identified with CO(2) cavography. One filter was maldeployed owing to misinterpretation of the CO(2) cavogram. CONCLUSION: CO(2) cavography is well tolerated, safe, and adequate for identification of the parameters necessary for filter deployment. It is especially valuable in patients with a history of reaction to iodinated contrast material or renal insufficiency.     

Intravascular ultrasound as an alternative to positive-contrast vena cavography prior to filter placement.

PURPOSE: In a nonconsecutive series of patients, intravascular ultrasound (IVUS) was investigated for safety and efficacy as an alternative to positive-contrast vena cavography for evaluating the inferior vena cava (IVC) prior to filter placement. MATERIALS AND METHODS: In a 6.5-year period, 30 patients (15 women, 15 men) ranging in age from 22 to 98 years old (mean, 56 years) underwent vena cava filter placement without conventional positive-contrast vena cavography, after IVUS evaluation of the IVC with use of a 6.2-F, 12.5- or 20-MHz monorail catheter system. The rationale for using IVUS included contraindications to iodinated contrast material in 14 patients with renal insufficiency and in four patients with previous life-threatening anaphylactoid reaction to iodinated contrast material; limitations to radiation exposure in four pregnant patients; and inability to otherwise image the IVC of eight morbidly obese patients who exceeded the weight limits of available angiographic equipment. IVUS completely replaced positive-contrast vena cavography, although not fluoroscopy in the four pregnant patients and in the 18 patients with contrast material contraindications. In two of the eight obese patients, IVUS was the only imaging modality. RESULTS: In all 30 patients, IVUS successfully determined the patency of the filter delivery route veins and the vena cava, the absence of thrombus, the location of renal veins, the absence of anatomical variants, and the vena cava diameter at the desired filter deployment level. Successful filter placement was confirmed in all 30 patients either with plain film alone (n = 12), IVUS alone (n = 3), computed tomography alone (n = 1), external ultrasound alone (n = 1), IVUS and another imaging modality (n = 10), or by combinations of other imaging modalities (n = 3). There were no complications. CONCLUSIONS: IVUS is a safe and effective alternative to conventional positive-contrast vena cavography for imaging the IVC prior to filter placement in patients with contraindications to iodinated contrast material or ionizing radiation.     

Gadolinium,carbon dioxide,and iodinated contrast material for planning inferior vena cava filter placement: a prospective trial

PURPOSE: To prospectively compare the diagnostic accuracy of CO(2) and gadolinium to iodinated contrast material for inferior vena cavography before inferior vena cava (IVC) filter placement. MATERIALS AND METHODS: Forty patients underwent injection of iodinated contrast material, CO(2), and gadolinium. Iodinated contrast material was used as the standard. Caval diameter was determined with calibrated software. Three readers blinded to contrast agent used measured the distance from the superior image border to the inferior margin of the renal veins and from the inferior image border to the iliac bifurcation. The measurements with CO(2) and gadolinium were compared to those with iodinated contrast material to obtain the interobserver and intraobserver variability. The presence or absence of caval thrombus and variant anatomy was noted. The same readers reexamined 12 studies in a separate session to determine intraobserver variability and correlation. RESULTS: Caval diameter differed by 0.4 mm or less for all three agents. Measurements with all agents were within 2 mm of each other for all patients. Gadolinium and CO(2) were not significantly different from one another in measuring caval diameter. At the initial reading, compared with iodinated contrast material, gadolinium had greater mean interobserver error in measuring the distance to the iliac bifurcation and both renal veins (range, 1.6-1.8 mm) than CO(2) (range, 0.2-1.4 mm). This finding, although statistically significant for gadolinium (P <.05), was of doubtful clinical relevance. Interobserver correlation was significantly worse for CO(2) at the levels of the iliac bifurcation (P =.02) and right renal vein (P =.008). Interobserver correlation for gadolinium was similar to that for iodinated contrast material at all levels. At repeat reading, there was significantly inferior intraobserver correlation with use of CO(2) for both renal veins (P <.05) compared to iodinated contrast material and for the left renal vein (P <.05) compared to gadolinium. Gadolinium identified three of three renal vein anomalies identified with iodinated contrast material whereas CO(2) localized one of three. CONCLUSION: CO(2) and gadolinium had limitations when compared with iodinated contrast material. Gadolinium provided superior consistency in identifying relevant landmarks for filter placement. CO(2) demonstrated significantly greater mean correlative error than gadolinium at initial and repeat readings.     

The diameter of the inferior vena cava and its implications for the use of vena caval filters

Inferior vena caval diameters were measured in 65 patients with Kimray-Greenfield (KG) inferior vena caval filters. The measurements were made at the distal tips of the filter tines on postplacement radiographs. Magnification corrections were made using the filter tine lengths as references. The overall mean diameter was 20 mm, the range was 13 to 30 mm, and the standard deviation was 3 mm. Two cavae (3%) were more than 28 mm in diameter. A previous in vitro study has shown that in venae cavae of this size there is a significant risk of reduced clot-capturing ability with the KG filter and migration with the Mobin-Uddin filter. Thus it is important to evaluate vena caval diameter by cavography prior to filter placement.     

Value of frontal caval measurement in the placement of inferior vena cava filters.

OBJECTIVE: Inferior vena cavae (IVC) can be of unusual geometry, often having odd shapes and being oriented (in long axes) away from the horizontal plane. However, after insertion of a filter, most IVC adopt a circular cross-section. The objective of this study was to determine if the IVC diameter estimated by frontal measurement (cavogram equivalent) reflects the true circular diameter of the infrarenal vena cava. Diameter estimation is clinically important in the correct selection of a filter, because mega cavae (diameter 28 mm or greater) require a particular filter. METHODS: The infrarenal IVC was measured on computed tomographic (CT) scans in 136 patients. The frontal diameter was recorded as that which would be obtained by a cavogram. Corrected circular diameter was obtained by mapping the circumference of each cross-section on CT to a straight line and calculating diameter from circumference. RESULTS: The average frontal caval diameter was 20.5 (standard deviation 3.7) mm, whereas the average corrected circular diameter was 23.0 (standard deviation 3.4) mm. By frontal measurements, 6 IVC diameters were 28.0 mm or greater. Similarly, by corrected circular diameter, 6 IVC diameters were 28.0 mm or greater. However, of the 6 mega cavae extrapolated to cavograms, only 3 corresponded to mega cavae when corrected for true circular diameter. Yet, of the 6 mega cavae identified by corrected circular diameter measurement, 3 were not identified by frontal diameter assessment. Of the 6 patients with true mega cavae, 2 were being evaluated for right lower quadrant pain, 2 for lymphoma, 1 for a pelvic mass, and 1 for staging of a head and neck cancer. CONCLUSIONS: Cavograms can over- or underestimate the true diameter of an IVC, and may thus lead to incorrect filter choice. It is recommended that a sonogram or CT scan be obtained to visualize the IVC in cases of suspected mega cava, and that true circular diameters be used for selection and placement of IVC filters.     

Use of the Bird's Nest filter in oversized inferior venae cavae.

An inferior vena cava (IVC) diameter of greater than 28 mm has been considered a contraindication to the intracaval placement of Greenfield, LG-Medical (LGM), and Simon nitinol filters, necessitating biiliac placement of these devices. With the Bird's Nest filter (BNF), the maximum span of the struts, which immobilize the device, is 60 mm; this allows the placement of the BNF in an oversized IVC having a diameter of greater than 28 mm. Over a 44-month period, 799 IVC filters (547 BNF, 136 Greenfield filters, and 116 LGM filters) were inserted. BNFs were placed in 18 patients (2.3%) with an oversized IVC (diameter range, 29-42 mm); all filters were placed via the femoral route. Patient records were reviewed to determine if problems were associated with filter insertion (including insertion site femoral vein thrombosis) and to determine the prevalence of filter migration, caval thrombosis, and new or recurrent pulmonary emboli (PE) after insertion. No difficulties were encountered during insertion. There was no documented case of device migration, caval thrombosis, or clinically apparent new or recurrent PE. The data suggest that the BNF is the filtering device of choice in patients with an oversized IVC.     

The Value of Preprocedure Computed Tomography for Planning Insertion of Inferior Vena Cava Filters

Purpose

To determine if valuable information could be obtained from abdominal computed tomography (CT) performed before insertion of an inferior vena cava (IVC) filter.

Materials and Methods

A retrospective review was performed on IVC filter insertions with a CT performed before the procedure. Cavagram and CT were compared for renal vein and IVC anatomy, the diameter of the IVC, and the prevalence of iliocaval thrombus. Correlations were assessed among 3 reference standards for measuring the IVC at cavography.

Results

The mean IVC diameter was 23.0 mm on CT. On cavagram the mean IVC diameter was assessed by using 3 reference standards: 20.7 mm, with the catheter tip as a reference; 26.9 mm, with a radiopaque ruler; and 23.4 mm, by using a lumbar vertebral body. There was good correlation among the 3 measures of IVC diameter (Pearson's r = 0.75, P < .0001) but moderate correlation with CT (r = 0.36–0.56, P < .001). The sensitivity of cavagram for detecting retroaortic and circumaortic renal veins was 40% and 0%, respectively. Nineteen accessory renal veins (12.8%) were not seen by cavagram. Thirteen patients (8.8%) had iliocaval thrombus on cavagram, of which 12 (92.3%) were not previously detected by CT.

Conclusions

CT is more sensitive than cavagram for detection of renal vein variants and the level of the lowest renal vein. Therefore, if available, the CT should be reviewed before placement of an IVC filter to optimize positioning. Cavagram remains the criterion standard for detection of iliocaval thrombosis and is necessary before IVC filter insertion.     

肝静脉阻塞的血管造影表现

目的 评价肝静脉阻塞的血管造影表现。方法 肝静脉阻塞患者45例，男23例，女22例；年龄9～54岁。全部病例均行下腔静脉造影和肝静脉造影。结果 肝静脉阻塞而下腔静脉通畅37例，肝静脉和下腔静脉同时阻塞8例。肝静脉阻塞而下腔静脉造影表现为肝内段下腔静脉局限性或普遍性狭窄31例，肝内段下腔静脉管径正常者12例，肝静脉开口处出现隔膜膨出征5例，副肝静脉开口处出现隔膜膨出征4例，肝静脉之间交通支形成45例。结论 下腔静脉造影能对肝静脉有无阻塞做出初步判断，隔膜膨出征是肝静脉和副肝静脉开口处膜性阻塞的直接征象，选择性肝静脉造影是诊断肝静脉阻塞的可靠依据。     

Accuracy of CO2 angiography in vessel diameter assessment: a comparative study of CO2 versus iodinated contrast material in an aortoiliac flow model

PURPOSE: Precise vessel sizing prior to endovascular intervention is critical to achievement of technical success. Diameter measurements obtained with CO2 and iodinated contrast material in an aortoiliac flow model were compared. MATERIALS AND METHODS: Aortoiliac flow was simulated in a compliant, silicone elastomer phantom of the aortoiliac system using an autoperfusion pump (flow volume, approximately 1100 mL/min; mean arterial pressure, 70-80 mm Hg at 80-90 cycles/minute) and a glycerol solution (40% by weight; viscosity 3.7 centipoise at 20 degrees C). Digital subtraction angiography was performed with the phantom in the anteroposterior (AP) plane and in three oblique planes with both CO2 and iodinated contrast material. Five sets of images for both CO2 and iodinated contrast material were obtained for each projection. Two readers independently performed vessel diameter measurements at seven sites (distal abdominal aorta, bilateral proximal and distal common iliac, and mid-external iliac arteries). The model was then evaluated with intravascular ultrasound (IVUS) using a 20-MHz imaging catheter. Actual diameter measurements were taken from the inner wall to inner wall in orthogonal planes at the same locations within the model, as described previously. Analysis was performed to determine local difference in measurements (t tests), difference when compared to the standard AP projection with iodinated contrast material (Dunnett's test) and inter-reader variability (Pitman's test). RESULTS: The contralateral iliac vessel segment did not opacify when imaging with CO2 in the 45 degrees obliquities; thus, 22 of 28 sites were available for comparison. At 18 of 22 (81.8%) sites, there was significant difference in vessel measurements (P < .01), with CO2 yielding a significantly larger diameter at 17 of 22 (77.3%) of the sites. The difference in mean diameter ranged from -1.28 to 4.47 mm. With use of the AP iodinated contrast material run as the standard, there were significant differences (P < .05) in vessel diameter at 17 of 22 (77.3%) and four of 21 (19%) sites for CO2 and iodinated contrast material respectively, with CO2 tending toward greater diameter measurements. Significant differences (P < .05) in variance between the two readers were present but occurred primarily with CO2 in the AP projection and iodinated contrast material in the 45 degrees left obliquity. With use of IVUS as the standard, there were significant differences (P < .05) in the measured vessel diameters with CO2 at nine of 22 (40.9%) of the sites and with iodinated contrast material at 17 of 28 (60.7%) of the sites. Of the measurements made with CO2, seven of nine (77.8%) of the measurements were of larger diameter than those obtained with IVUS. By contrast, of the measurements made with iodinated contrast material angiography, IVUS measured larger diameters in 16 of 17 (94.1%). CONCLUSION: CO2 angiography consistently yielded significantly larger vessel measurements when compared to both iodinated contrast angiography and WVUS. These results have important implications in regards to planning intervention based solely on CO2 angiography. Further evaluation is needed before recommending CO2 for vessel sizing in clinical practice.     

Comparison of filters in an oversized vena caval phantom: intracaval placement of a bird's nest filter versus biiliac placement of Greenfield, Vena Tech-LGM, and Simon nitinol filters.

For patients with an oversized inferior vena cava (IVC) (diameter greater than 28 mm, corrected for magnification) who require vena caval filtration for prophylaxis against pulmonary emboli, the accepted treatment has been the biiliac venous placement of Greenfield filters. Because of its wide strut span, the Bird's Nest filter (BNF) has been successfully placed in patients having an oversized IVC. However, the effects of the BNF on caval blood flow and its clot-capturing ability in an oversized IVC are not clearly understood. The authors created a flow phantom simulating an oversized IVC with "iliac" tributaries of normal inner diameter to analyze flow turbulence, pressure gradients, and the clot-capturing ability of the BNF, tested within the "caval" segment of the phantom, and the Greenfield, Vena Tech-LGM, and Simon nitinol filters, tested in the "iliac" segments. All filters were tested for flow disturbances before and after clot capture. The authors' results demonstrate that within an oversized IVC, the BNF creates less flow disturbance and is less occlusive with clot capture than biiliac filters. The BNF displayed a clot-capturing ability equal to that of biiliac filters. Thus, for patients with an oversized IVC, these results suggest that placement of a single intracaval BNF is preferable to biiliac placement of filters.     

Evaluation of the inferior vena cava with intravascular US after Greenfield filter placement.

An animal model was used to evaluate the utility of intravascular ultrasound (US) imaging of the inferior vena cava (IVC) following Greenfield filter placement. Ten Greenfield filters were placed in the IVCs of five sheep and three dogs. Experimentally induced thrombi were injected into four filters at the time of placement. Intravascular US and cavography were performed 4 weeks after filter implant. The imaging studies were evaluated for demonstration of filter position, orientation, and leg distribution, as well as prediction of caval wall penetration by filter hooks. Experimentally induced and spontaneous intrafilter thrombi were also imaged. Findings were compared with those of postmortem examination. Exact filter position and orientation were most simply and accurately demonstrated on radiographs. Filter leg distribution and extent of intrafilter thrombus were best evaluated on intravascular US images. The prevalence of caval wall penetration was underestimated with both studies. The results of this animal study suggest that the information about the IVC provided at cavography and intravascular US following Greenfield filter placement may be complementary.     

下腔静脉滤器预防肺栓塞及其并发症

目的 探讨下腔静脉滤器置入术(IVCF)预防肺动脉栓塞(PE)的疗效、相关并发症及处理.方法70例下肢深静脉血栓患者,溶(取)栓术前均行下腔静脉滤器置入术:永久性Trap Ease滤器(TEF)20枚,永久性Vena Tech滤器(VTF)31枚,可回收性OptEase~(TM)滤器(OEF)13枚,临时性TempoⅡ滤器8枚;71枚位置在肾静脉开口下方,1枚位置在肾静脉开口上方.结果 术后随访8～72个月.70例中,无一例出现PE,6例出现相关的并发症.结论 下腔静脉滤器置入可以有效预防肺梗死,但应严格掌握适应证.     

Inferior vena caval filter thrombi: evaluation with intravascular US

A 20-MHz intravascular ultrasound (US) transducer inside a percutaneously inserted catheter was used to evaluate inferior vena caval (IVC) filters for thrombi in vitro and in vivo. Six different IVC filters were studied with intravascular US in a saline-filled model. Each filter had a characteristic, recognizable US pattern. Experimental thrombi as small as 0.5 cm3 were easily detected. Intravascular US was used clinically 25 times to evaluate the IVC in 23 patients with 24 IVC filters. Positive-contrast cavograms were available for comparison in all 25 cases. In 13 cases, no thrombi were identified in the filter or IVC with either intravascular US or cavography; in five of 12 cases with thrombi, intravascular US and cavography demonstrated the thrombi equally well. In six cases, intravascular US was superior to cavography in detection or delineation of thrombus in the IVC or filter. Intravascular US was considered superior to external duplex US in evaluation of caval thrombi in all 21 cases available for comparison. No complications from intravascular US were noted.     

Recurrent pulmonary embolism after Greenfield filter placement

Three patients with documented recurrent pulmonary embolism with an inferior vena cava (IVC) Greenfield filter in place were examined with contrast-material-enhanced cavography. Mechanisms for recurrent pulmonary embolism were found to be propagation of thrombus through the filter struts, occlusion of the IVC at the level of the filter, and loss of contact of the filter hooks with a portion of the caval wall.     

Inferior vena cava filter tilting between placement and retrieval is associated with caval diameter and need for complex retrieval techniques

PurposeInferior vena cava (IVC) filter tilt may lead to apex embedment and need for advanced retrieval techniques. This study assesses factors associated with filter tilt change over time and need for complex retrieval procedures.Materials and methods252 consecutive patients underwent retrievable IVC filter placement and removal at a single academic institution over 58 months. 182 (72.2%) patients met inclusion criteria. IVC filters included 168 (92.3%) Gunther Tulip and 14 (7.7%) Option filters. The primary outcome was medial-to-lateral IVC filter tilt change between placement and retrieval. Secondary outcomes included advanced retrieval technique use and multiple retrieval attempts. Independent variables included demographics, IVC diameter, filter hook position relative to the renal veins, and dwell time. Associations were determined using student's t-tests, ANOVA, and linear and logistic regressions.ResultsMean IVC diameter at placement was 19.2 ± 3.3 mm. Mean filter tilts at placement and retrieval were 6.1 ± 4.9° and 5.2 ± 5.0°, respectively. Mean tilt change was 5.0 ± 5.0°. Larger IVC diameter was associated with greater filter tilt change (p = 0.0004). While IVC diameter did not independently predict retrieval difficulty, greater tilt change and prolonged dwell time were associated with increased advanced retrieval technique use (p = 0.01 and 0.002, respectively). Results were unchanged in a subgroup analysis of patients treated with Gunther Tulip filters.ConclusionLarger IVC diameter predicts increased filter tilt change, which in turn is associated with challenging retrievals. Attention to IVC diameter during filter placement may anticipate tilt-related complications.     

Angioscopy for experimental evaluation of optional IVC filters

PURPOSE: To demonstrate the feasibility of direct angioscopic visualization of an optional inferior vena cava (IVC) filter in situ and during retrieval. MATERIALS AND METHODS: Angioscopy was used for direct visualization of optional IVC filters in six sheep. Cavograms were obtained before the filters were retrieved. After successful filter retrieval, segmental IVC perfusion was performed to evaluate filter retrieval-related damage to the IVC wall. Therefore, all branch vessels were ligated before the IVC segment was flushed with normal saline solution until it was fully distended. Then, the inflow was terminated and the IVC segment observed for deflation. Subsequently, the IVC was harvested en bloc, dissected, and inspected macroscopically. RESULTS: The visibility of IVC filters at angioscopy was excellent. During the retrieval procedure, filter collapse and retraction into the sheath were clearly demonstrated. Angioscopy provided additional information to that obtained with cavography, demonstrating adherent material in three filters. Three filters in place for more than 2 months could not be retrieved because the filter legs were incorporated into the IVC wall. After filter retrieval, there was no perforation at segmental IVC perfusion. At macroscopic inspection of the IVC lumen, a small piece of detached endothelium was found in one animal. CONCLUSION: Angioscopy enabled the direct evaluation of optional IVC filters in situ and during retrieval. Compared with cavography, angioscopy provided additional information about the filter in situ and the retrieval procedure. Future applications of this technique could include studies of filter migration, compression, and clot-trapping efficacy.     

The Günther temporary inferior vena cava filter for short-term protection against pulmonary embolism

Purpose To evaluate clinically the Günther temporary inferior vena cava (IVC) filter. Methods Eleven IVC filters were placed in 10 patients. Indications for filter placement were surgical pulmonary embolectomy in seven patients, pulmonary embolism in two patients, and free-floating iliofemoral thrombus in one patient. Eight filters were inserted from the right femoral approach, three filters from the left. Follow-up was by plain abdominal radiographs, cavography, and duplex ultrasound (US). Eight patients received systemic heparinization. Follow-up, during 4–60 months after filter removal was by clinical assessment, and imaging of the lungs was performed when pulmonary embolism (PE) was suspected. Patients received anticoagulation therapy for at least 6 months. Results Ten filters were removed without complications 7–14 days (mean 10 days) after placement. One restless patient pulled the filter back into the common femoral vein, and a permanent filter was placed. In two patients a permanent filter was placed prior to removal. One patient developed sepsis, and one an infection at the insertion site. Clinically no recurrent PE developed with the filter in place or during removal. One patient had recurrent PE 7 months after filter removal. Conclusion The Günther temporary IVC filter can be safely placed for short-term protection against PE. The use of this filter is not appropriate in agitated or immunocompromised patients.     

Early and Late Retrieval of the ALN Removable Vena Cava Filter: Results from a Multicenter Study

Retrieval of removable inferior vena cava (IVC) filters in selected patients is widely practiced. The purpose of this multicenter study was to evaluate the feasibility and results of percutaneous removal of the ALN removable filter in a large patient cohort. Between November 2003 and June 2006, 123 consecutive patients were referred for percutaneous extraction of the ALN filter at three centers. The ALN filter is a removable filter that can be implanted through a femoral/jugular vein approach and extracted by the jugular vein approach. Filter removal was attempted after an implantation period of 93 ± 15 days (range, 6–722 days) through the right internal jugular vein approach using the dedicated extraction kit after control inferior vena cavography. Following filter removal, vena cavograms were obtained in all patients. Successful extraction was achieved in all but one case. Among these successful retrievals, additional manipulation using a femoral approach was needed when the apex of the filter was close to the IVC wall in two patients. No immediate IVC complications were observed according to the postimplantation cavography. Neither technical nor clinical differences between early and late filter retrieval were noticed. Our data confirm the safety of ALN filter retrieval up to 722 days after implantation. In infrequent cases, additional endovenous filter manipulation is needed to facilitate extraction.     

Vena Cava Filter Behavior and Endovascular Response: An Experimental In Vivo Study

Purpose: To evaluate the behavior and endovascular response of a new nitinol permanent vena cava filter, the TrapEase. Methods: Percutaneous implantation of the filter was performed in six goats, with inferior vena cava (IVC) diameter close to that of man. Radiologic data concerning the IVC, filter diameter, patency and stability were collected. At 2, 4, 20 and 26 weeks post-implantation, histopathologic analysis of the IVC wall was performed at the site of filter distension, and distal and proximal to the filter. Results: All filters remained patent. There was no migration and no signs of biological incompatibility. Signs of neointimalization were seen at 2 weeks, with well-developed neointima at 4 weeks. No acute vessel wall perforation was detected by cavography at implantation. During follow-up histologic analysis at 26 weeks, perforation of some of the small fixation barbs was seen, causing minimal damage to the vessel wall and adjacent organ tissue without impairing organ function. These events were well tolerated, probably due to the gradual nature of the penetration of fixation barbs allowing reactive fibrous tissue development. At 26 weeks the parallel filter struts were well covered with neointima and did not perforate the vessel wall. There were no complications associated with the filter implantation. Conclusions: The TrapEase vena cava filter was well tolerated and is suitable for incorporation into the IVC wall of healthy animals without any apparent deleterious reaction due to biological incompatibility.     

Radionuclide cavography before and after percutaneous transluminal angioplasty in Budd-Chiari web: case report

A case of the Budd-Chiari syndrome due to a web of the hepatic inferior vena cava (IVC) is reported. A 54-year-old male with mild liver dysfunction was suspected with IVC obstruction from the screening CT which revealed liver cirrhosis with marked caudate lobe enlargement and dilatation of azygous and hemiazygous vein. Subsequent radionuclide cavography with 99mTc-HSA clearly demonstrated IVC obstruction, but failed to clarify the site or type of the obstruction. Finally contrast cavography diagnosed a web of the hepatic IVC, which was treated by percutaneous transluminal angioplasty (PTA). During two-year follow-up after PTA none of the radionuclide cavographies showed reocclusion of the IVC and as a result contrast cavography was avoided. Radionuclide cavography, therefore, was a useful method for evaluating IVC obstruction before and after PTA for the Budd-Chiari web.