Matthew D. B. S. Tam

Fracture and Distant Migration of the Bard Recovery Filter: A Retrospective Review of 363 Implantations for Potentially Life-Threatening Complications

PURPOSE To report the occurrence of fracture of the Recovery filter and incidence of potentially life-threatening complications associated with fractured fragment migration. MATERIALS AND METHODS A retrospective study of images obtained after placement of Recovery inferior vena cava (IVC) filters from 2003 to 2006 was conducted at a single tertiary-care center. Images were reevaluated for fracture and migration; complications related to filter fracture were investigated. Kaplan-Meier survival analysis was performed to investigate the relationship between time in situ and fracture. RESULTS A total of 363 Recovery filters were placed; 97 were retrieved, leaving 266 filters in situ (135 patients subsequently died of other causes). The following images were evaluated: 130 chest computed tomography (CT) scans, 153 abdominal CT scans, 254 chest radiographs, 148 radiographs of the abdomen/pelvis, and 106 cavagrams. Mean imaging follow-up interval was 18.4 months (maximum, 81.3 mo). No en bloc migration occurred outside the IVC. Twenty-six limb fractures (all short limbs) were identified in 20 patients; the earliest occurred at 4.1 months. Eight fragment migrations occurred into pulmonary arteries, seven into iliac/femoral veins, one into the right ventricle, and one into the renal vein. Seven fragments were intracaval near the filter, one was extracaval, and one could not be located. Kaplan-Meier survival estimates predicted a fracture rate of 40% at 5.5 years. Of the 20 patients with filter fractures, three died of unrelated causes and 17 remain asymptomatic. CONCLUSIONS Recovery filter fractures occurred at the short limb only, with a suggested 5.5-year fracture risk of 40%. No life-threatening events occurred in patients with filter fracture.

Building virtual models by postprocessing radiology images: A guide for anatomy faculty.

Radiology and radiologists are recognized as increasingly valuable resources for the teaching and learning of anatomy. State‐of‐the‐art radiology department workstations with industry‐standard software applications can provide exquisite demonstrations of anatomy, pathology, and more recently, physiology. Similar advances in personal computers and increasingly available software can allow anatomy departments and their students to build their own three‐dimensional virtual models. Appropriate selection of a data‐set, followed by processing and presentation are the key steps in creating virtual models. The construction, presentation, clinical application, and educational potential of postprocessed imaging techniques including multiplanar reformats, minimum intensity projections, segmentation, volume‐rendering, surface‐rendering, fly‐throughs, virtual endoscopy, angiography, and cine‐loops are reviewed using examples created with only a personal computer and freeware software. Although only static images are presented in this article, further material is available online within the electronic version of this article. Through the use of basic and advanced image reconstruction and also paying attention to optimized presentation and integration, anatomy courses can be strengthened with appropriate radiological material. There are several key advantages for the anatomy department, which is equipped with the ability to produce virtual models using radiology images: (1) Opportunities to present anatomy using state‐of‐the‐art technology as an adjunct to current practices, (2) a means to forge an improved relationship with the local radiology department, and (3) the ability to create material locally, which is integrated with the local curriculum avoiding the problem of information overload when using the internet or other commercially available resources. Anat Sci Educ 3:261–266, 2010.

Retrievability and Device-Related Complications of the G2 Filter: A Retrospective Study of 139 Filter Retrievals

PURPOSE To evaluate the retrievability and safety of the G2 filter. MATERIALS AND METHODS A retrospective study of all G2 filter retrievals at a single institution was conducted. Hospital records and imaging studies were reviewed for complications, and factors affecting retrieval were analyzed. RESULTS From 2005 to 2009, a total of 139 patients presented for retrieval of their G2 filter, and 131 pairs of pre- and post-placement cavagrams and 39 computed tomography scans were available for analysis. The following findings were recorded: limb penetration (n = 33), tilt greater than 15° (n = 22), local migration greater than 2 cm (n = 17), retained thrombus within the filter (n = 16), deformity (n = 10), inferior vena cava (IVC) occlusion (n = 3), fracture (n = 2), and pulmonary embolism breakthrough (n = 2). A total of 118 filters were removed, with a mean indwelling time of 131.8 days (range, 3-602 d). Indwell time (< 90, 90-180, or > 180 d) did not affect retrieval (P = .4). There were 21 filters (15.1%) left in situ as a result of severe tilt (n = 9), significant thrombus in the filter (n = 5), IVC occlusion (n = 3), filter incorporation into the caval wall (n = 3), or lack of central venous access (n = 1). There was a strong relationship between penetration and caudal migration (P < .0001). Severe tilt was associated with prolonged fluoroscopic times for retrieval (P = .003). CONCLUSIONS The majority of G2 filters can be removed without difficulty. The most common factor affecting retrieval was severe tilting. The indwelling time had no impact on retrieval. G2 filter-related complications were frequent but most, including fractures, were clinically insignificant.

Caval Penetration by Inferior Vena Cava Filters A Systematic Literature Review of Clinical Significance and Management

Background— Limited penetration into the caval wall is an important securing mechanism for inferior vena cava (IVC) filters; however, caval penetration can also cause unintentional complications. The aim of this study was to assess the incidence, severity, clinical consequences, and management of filter penetration across a range of commercially available IVC filters. Methods and Results— The MEDLINE database was searched for all studies (1970–2014) related to IVC filters. A total of 88 clinical studies and 112 case reports qualified for analysis; these studies included 9002 patients and 15 types of IVC filters. Overall, penetration was reported in 19% of patients (1699 of 9002), and 19% of those penetrations (322 of 1699) showed evidence of organ/structure involvement. Among patients with penetration, 8% were symptomatic, 45% were asymptomatic, and 47% had unknown symptomatology. The most frequently reported symptom was pain (77%, 108 of 140). Major complications were reported in 83 patients (5%). These complications required interventions including surgical removal of the IVC filter (n=63), endovascular stent placement or embolization (n=11), endovascular retrieval of the permanent filter (n=4), and percutaneous nephrostomy or ureteral stent placement (n=3). Complications led to death in 2 patients. A total of 87% of patients (127 of 146) underwent premature filter retrieval or interventions for underlying symptoms or penetration-related complications. Conclusions— Caval penetration is a frequent but clinically underrecognized complication of IVC filter placement. Symptomatic patients accounted for nearly 1/10th of all penetrations; most of these cases had organ/structure involvement. Interventions with endovascular retrieval and surgery were required in most of these symptomatic patients. # CLINICAL PERSPECTIVE {#article-title-44}Background— Limited penetration into the caval wall is an important securing mechanism for inferior vena cava (IVC) filters; however, caval penetration can also cause unintentional complications. The aim of this study was to assess the incidence, severity, clinical consequences, and management of filter penetration across a range of commercially available IVC filters. Methods and Results— The MEDLINE database was searched for all studies (1970–2014) related to IVC filters. A total of 88 clinical studies and 112 case reports qualified for analysis; these studies included 9002 patients and 15 types of IVC filters. Overall, penetration was reported in 19% of patients (1699 of 9002), and 19% of those penetrations (322 of 1699) showed evidence of organ/structure involvement. Among patients with penetration, 8% were symptomatic, 45% were asymptomatic, and 47% had unknown symptomatology. The most frequently reported symptom was pain (77%, 108 of 140). Major complications were reported in 83 patients (5%). These complications required interventions including surgical removal of the IVC filter (n=63), endovascular stent placement or embolization (n=11), endovascular retrieval of the permanent filter (n=4), and percutaneous nephrostomy or ureteral stent placement (n=3). Complications led to death in 2 patients. A total of 87% of patients (127 of 146) underwent premature filter retrieval or interventions for underlying symptoms or penetration-related complications. Conclusions— Caval penetration is a frequent but clinically underrecognized complication of IVC filter placement. Symptomatic patients accounted for nearly 1/10th of all penetrations; most of these cases had organ/structure involvement. Interventions with endovascular retrieval and surgery were required in most of these symptomatic patients.

Use of a 3D printed hollow aortic model to assist EVAR planning in a case with complex neck anatomy: potential of 3D printing to improve patient outcome.

Three-dimensional (3D) printing has progressed to the point that it now has a role in surgical planning, prosthesis design, and also patient communication. While hearing aids, facial reconstruction, and orthopedic implants lead the field, aortic models have been made using both casts and 3D printing techniques. As we showed in our previous work, data derived from computed tomography (CT) can be post-processed on standard CT workstations to segment the lumen of an aortic aneurysm from the suprarenal aorta to the common femoral arteries in less than 10 minutes. With the CT workstation networked to an image processing computer, the segmented data undergo surface rendering to produce solid models. The mesh is then edited in computer-aided design (CAD) software and Laplacian smoothing algorithms are applied to smooth the mesh; any mathematical errors that result from the processing are corrected. To create hollow models, a virtual cast must be formed around the solid model. The segmentation is binarized, and the data are then run through a proprietary algorithm that grows a virtual cast around the segmentation. This is re-imported into the editing software and converted into a file format suitable for printing. Solid models can also be printed and used to cast hollow models using traditional liquid silicone rubber molding and casting techniques. Direct 3D printing of hollow models is, however, a one-step process and is therefore faster and more accurate. Though there are a number of commercially available printing services, the art remains in segmentation, particularly in cases without perfect arterial enhancement or where there is local venous contamination, calcification, or bone. A recent case we encountered illustrates the potential of these hollow models. A patient with an abdominal aortic aneurysm had a highly angulated aortic neck with vertical takeoff of the renal arteries and a 15-mm shelf of horizontal neck below the renal artery on center lumen line analysis (Fig. 1A). We created a hollow model to test deploy a stent-graft prior to performing endovascular aneurysm repair (EVAR). The graft was deployed in the hollow model (Fig. 1B), which was inspected (Fig. 1C) and scanned (Fig. 1D) prior to the procedure. The clinical implantation went well (Fig. 1E), and CT surveillance (Fig. 1F) at 6 weeks confirmed satisfactory graft placement. Although materials that are individually clear or flexible (Fig. 2) are available for transparent printing, insofar as we know, there is no material that is both flexible and purely transparent. Since rigid plastic models cannot accept a graft delivery system, there is currently a tradeoff between transparency and flexibility, but it is only a matter of time before materials in development become available. As the material costs for an aortic stentgraft are around

Acute Abdominal Pain After Retrievable Inferior Vena Cava Filter Insertion: Case Report of Caval Perforation by an Option Filter

6,000, spending

Tackling climate change close to home: Mobile breast screening as a model

300 to produce two models, a solid one to review the neck anatomy and a hollow transparent cast for direct ‘‘pre-flight’’ simulation prior to the clinical case, is a feasible paradigm. The hollow models could be ‘‘snapped in’’ and ‘‘snapped out’’ of a modular simulator. These 3D models might therefore aid case selection, particularly in off-label applications, which are more likely to have complications. Thus, model-assisted endovascular aneurysm repair might also improve patient outcomes (Fig. 3). In summary, 3D printing of aortic aneurysms is feasible, and streamlined computer programs that can make it easier to move between radiology and CAD are needed. Caution must be exercised with automated segmentation processes, and accuracy of models must be overseen by endovascular operators with their excellent understanding 760 J ENDOVASC THER 2014;21:760–764

A Pilot Study Assessing the Impact of 3-D Printed Models of Aortic Aneurysms on Management Decisions in EVAR Planning.

Symptomatic caval injury is rare after inferior vena cava (IVC) filter insertion. A 39-year-old woman developed acute abdominal pain after uneventful placement of a retrievable Option IVC Filter (Angiotech Pharmaceuticals, Vancouver, British Columbia, Canada). Two days after placement, computed tomography showed a right-sided retroperitoneal hematoma, and three-dimensional C-arm rotational venography confirmed limb penetration beyond the caval wall. This is the first report of this complication despite two recent studies highlighting the safety profile of this relatively new filter.

Gelfoam-Assisted Amplatzer Vascular Plug Technique for Rapid Occlusion in Proximal Splenic Artery Embolization

Objective Health services contribute significantly to carbon dioxide (CO2) emissions and, while services in the UK are beginning to address this, the focus has been on reducing energy consumption rather than road transport, a major component of emissions. We aimed to compare the distances travelled by patients attending mobile breast screening clinics compared to the distance they would need to travel if screening services were centralized. Methods Anonymized postcode records were analysed to determine driving distances potentially saved through attendance at 20 mobile breast screening clinics rather than at two centralized locations. Based on assumptions for the typical car used, the CO2 emissions were calculated for the current case of decentralized service through mobile clinics compared to a hypothetical case where only centralized services are available over one complete three-year cycle of breast screening invitations. Results The availability of mobile breast screening clinics for the 60,675 women who underwent screening over a three-year cycle led to a return journey distance savings of 1,429,908 km. Taking into account the CO2 emissions of the tractor unit used for moving the mobile clinics around, this equates to approximately 75 tonnes of CO2 saved in any one year. Conclusions Decentralizing health care delivery can potentially provide substantial reductions in emissions at the same time as improving the patient experience. Thus, the ‘care close to home’ agenda can simultaneously improve health outcomes and the environment.

Use of an Amplatzer Vascular Plug II for Aortic Sac Occlusion After Failed Surgical Ligation

Introduction: Endovascular repair of aortic aneurysms with difficult anatomy is challenging. There is no consensus for planning such procedures. Methods: Six cases of aortic aneurysms with challenging anatomical features, such as short, angulated, and conical necks and tortuous iliacs were harvested. The computed tomography (CT) scans were anonymized. Lifesize 3-dimensional (3-D) printed models were created of the lumen. Endovascular operators were asked to review the CT angiography (CTA), make a management plan, and give an indication of their confidence. They were then presented with the equivalent model and asked to review their decision. Their attitudes to such models were briefly surveyed. Results: A total of 28 endovascular operators reviewed 144 cases. After review of the physical model, the management plan changed in 29 (20.1%) of 144 cases. Initial plan after CTA review was endovascular 73.6%, open repair 22.9%, and second opinion 3.5%. After model review, this became endovascular 67.4%, open repair 19.4%, and second opinion 4.8%. Although the general trend was toward more open procedures, off-label techniques reduced from 19.4% to 15.2% following model review. When the management plan did not change, level of confidence did increase in 37 (43.5%) of 85 cases. The majority of operators stated that they would find models useful for planning in some procedures. For 1 case, the change in the percentage of participants being sure in the management plan was statistically significant (P = .031). Conclusion: The 3-D printed models may be potentially useful in planning cases with EVAR. It is a paradigm that warrants further investigation.