Robert J. Abraham

Thrombin Injection for Treatment of Brachial Artery Pseudoaneurysm at the Site of a Hemodialysis Fistula: Report of Two Patients

We report two patients with arteriovenous hemodialysis fistulas that were complicated by brachial artery pseudoaneurysms. Each pseudoanerysm was percutaneously thrombosed with an injection of thrombin, using techniques to prevent escape of thrombin into the native brachial artery. In one patient, an angioplasty balloon was inflated across the neck of the aneurysm during thrombin injection. In the second patient, thrombin was injected during ultrasound-guided compression of the neck of the pseudoaneurysm. Complete thrombosis of each pseudoaneurysm was achieved within 30 sec. No ischemic or embolic events occurred. This technique may be useful in treating pseudoaneurysms of smaller peripheral arteries.

Mixture designs to assess composition–structure–property relationships in SiO2–CaO–ZnO–La2O3–TiO2–MgO–SrO–Na2O glasses: Potential materials for embolization

Embolization with micron-sized particulates is widely applied to treat uterine fibroids. The objective of this work was to develop mixture designs to predict materials composition–structure–property relationships for the SiO2–CaO–ZnO–La2O3–TiO2–MgO–SrO–Na2O glass system and compare its fundamental materials properties (density and cytocompatibility), against a state-of-the-art embolic agent (contour polyvinyl alcohol) to assess the potential of these materials for embolization therapies. The glass structures were evaluated using 29Si MAS NMR to identify chemical shift and line width; the particulate densities were determined using helium pycnometry and the cell viabilities were assessed via MTT assay. 29Si MAS NMR results indicated peak maxima for each glass in the range of −82.3 ppm to −89.9 ppm; associated with Q2 to Q3 units in silicate glasses. All experimental embolic compositions showed enhanced in vitro compatibility in comparison to Contour PVA with the exceptions of ORP9 and ORP11 (containing no TiO2). In this study, optimal compositions for cell viability were obtained for the following compositional ranges: 0.095–0.188 mole fraction ZnO; 0.068–0.159 mole fraction La2O3; 0.545–0.562 mole fraction SiO2 and 0.042–0.050 mole fraction TiO2. To ensure ease of producibility in obtaining good melts, a maximum loading of 0.068 mole fraction La2O3 is required. This is confirmed by the desirability approach, for which the only experimental composition (ORP5) of the materials evaluated was presented as an optimum composition; combining high cell viability with ease of production (0.188 mole fraction ZnO; 0.068 mole fraction La2O3; 0.562 mole fraction SiO2 and 0.042 mole fraction TiO2).

Laparoscopic accessory splenectomy: the value of perioperative localization studies

BackgroundLaparoscopic splenectomy is an effective treatment for many patients with immune thrombocytopenic purpura (ITP) who fail or relapse after treatment with steroids. Patients with an incomplete response to splenectomy and those who experience recurrence of symptoms should be evaluated for the presence of an accessory spleen. The clinical effectiveness of laparoscopic excision of an accessory spleen after a previous splenectomy for ITP has varied in different studies. Laparoscopic intraoperative identification of an accessory spleen can be difficult. The authors report their experience with laparoscopic accessory splenectomy (LAS) and the use of perioperative localization methods for this procedure.MethodsThis study reviewed seven consecutive patients who underwent LAS, after initial splenectomy failed to cure ITP, at a tertiary care center between April 9, 2003 and March 31, 2008. Demographics, diagnostic and localization studies, technical success, and the effect on thrombocytopenia were examined. The location of the accessory spleen also was recorded. A novel method for localizing accessory spleen was used. It consisted of preoperative computed tomography (CT)-guided injection of methylene blue at the accessory spleen’s site, preoperative intravenous injection of 99m-technetium-labeled, heat-damaged red blood cells, or both. Intraoperatively, the dye was used for visual identification, and the gamma probe was used to aid in locating and confirming the presence of the accessory spleen in the excised specimen.ResultsSeven patients with recurrent ITP after initial failed splenectomy underwent LAS during the study period. Five of these patients had the initial splenectomy performed laparoscopically. All seven patients had successful laparoscopic removal of the accessory spleen based on a final pathologic examination. One patient required the second laparoscopic exploration with perioperative localization after a failed attempt without it. These perioperative localization methods were used in subsequent operations on other patients. These methods were found to be helpful in the intraoperative identification of the accessory spleens. The accessory spleens missed at initial splenectomy were found in unusual locations. Five of the seven patients had sustained improvement in platelet counts after LAS. One patient had a postoperative ileus that resolved with nonoperative management. No other complications or mortality was observed.ConclusionThe LAS procedure after previous splenectomy is feasible and safe. Perioperative localization methods aid in the intraoperative identification of an accessory spleen. Accessory spleens missed at initial splenectomy are generally found in unusual locations. Treatment of recurrent or unresolved ITP with LAS can be effective for some patients.

Endovascular Exclusion of a Splenic Artery Aneurysm Using a Pipeline Embolization Device

The Pipeline Embolization Device (ev3 Endovascular Inc, Plymouth, Minnesota) is a new endovascular device designed to exclude suitable intracranial aneurysms. A 56-year-old woman presented with a symptomatic 4.1-cm splenic artery aneurysm (SAA) that was successfully managed with a two-staged treatment plan involving selective segmental splenic artery embolization and subsequent deployment of a Pipeline Embolization Device across the aneurysm neck to exclude the aneurysm and maintain splenic perfusion.

Composition-property relationships for radiopaque composite materials: pre-loaded drug-eluting beads for transarterial chemoembolization

The purpose of this study was to synthesize and optimize intrinsically radiopaque composite embolic microspheres for sustained release of doxorubicin in drug-eluting bead transarterial chemoembolization. Using a design of experiments approach, 12 radiopaque composites composed of polylactic-co-glycolic acid and a radiopaque glass (ORP5) were screened over a range of compositions and examined for radiopacity (computed tomography) and density. In vitro cell viability was determined using an extract assay derived from each composition against the human hepatocellular carcinoma cell line, HepG2. Mathematical models based on a D-Optimal response surface methodology were used to determine the preferred radiopaque composite. The resulting radiopaque composite was validated and subsequently loaded with doxorubicin between 0 and 1.4% (wt% of polylactic-co-glycolic acid) to yield radiopaque composite drug-eluting beads. Thereafter, the radiopaque composite drug-eluting beads were subjected to an elution study (up to 168 h) to determine doxorubicin release profiles (UV-Vis spectroscopy) and in vitro cell viability. Radiopaque composites evaluated for screening purposes had densities between 1.28 and 1.67 g.cm−3, radiopacity ranged between 211 and 1450HU and cell viabilities between 91 and 106% were observed. The optimized radiopaque composite comprised 23 wt% polylactic-co-glycolic acid and 60 wt% ORP5 with a corresponding density of 1.63 ± 0.001 g.cm−3, radiopacity at 1930 ± 44HU and cell viability of 89 ± 7.6%. Radiopaque composite drug-eluting beads provided sustained doxorubicin release over 168 h. In conclusion, the mathematical models allowed for the identification and synthesis of a unique radiopaque composite. The optimized radiopaque composite had similar density and cell viability to commercially available embolic microspheres. It was possible to preload doxorubicin into radiopaque composite drug-eluting beads, such that sustained release was possible under simulated physiological conditions.

Preliminary Investigation of the Dissolution Behavior, Cytocompatibility, Effects of Fibrinogen Conformation and Platelet Adhesion for Radiopaque Embolic Particles

Experimental embolic particles based on a novel zinc-silicate glass system have been biologically evaluated for potential consideration in transcatheter arterial embolization procedures. In addition to controlling the cytotoxicity and haemocompatibility for such embolic particles, its glass structure may mediate specific responses via dissolution in the physiological environment. In a 120 h in-vitro dissolution study, ion release levels for silicon (Si4+), sodium (Na+), calcium (Ca2+), zinc (Zn2+), titanium (Ti4+), lanthanum (La3+), strontium (Sr2+), and magnesium (Mg2+), were found to range from 0.04 to 5.41 ppm, 0.27–2.28 ppm, 2.32–8.47 ppm, 0.16–0.20 ppm, 0.12–2.15 ppm, 0.16–0.49 ppm and 0.01–0.12 ppm, respectively for the series of glass compositions evaluated. Initial release of Zn2+ (1.93–10.40 ppm) was only evident after 120 h. All compositions showed levels of cell viabilities ranging from 61.31 ± 4.33% to 153.7 ± 1.25% at 25%–100% serial extract dilutions. The conformational state of fibrinogen, known to induce thrombi, indicated that no changes were induced with respect of the materials dissolution by-products. Furthermore, the best-in-class experimental composition showed equivalency to contour PVA in terms of inducing platelet adhesion. The data generated here provides requisite evidence to continue to in-vivo pre-clinical evaluation using the best-in-class experimental composition evaluated.

Imageable Zinc-Silicate Glass Microspheres For Transarterial Embolization: A Renal Artery Embolization Study.

Abstract Intrinsically radiopaque (imageable) microspheres for transarterial embolization (TAE) are required to enable real-time intraprocedural feedback and definition of spatial distribution patterns of embolic materials in target tissues. This pilot study evaluates acute and sub-chronic safety and efficacy of imageable zinc-silicate (Zn-Si) glass microspheres in a swine renal artery embolization (RAE) model. Eight swine were divided into two cohorts. Clinical determinants of embolization effectiveness, including imageability, deliverability and temporal/ spatial distribution of microspheres in target tissues were assessed. Subsequently, cohort I and II were used to evaluate the acute and subchronic host response against the Zn-Si microspheres versus a clinical control. The developed microspheres provide for direct intraprocedural feedback using standard diagnostic imaging techniques. Fluoroscopy correlated with ex-vivo high-resolution radiography, CT and micro-CT, demonstrating high imageability, excellent spatial distribution and packing of the Zn- Si microspheres. At follow-up, infarction of the embolized kidneys was noted without any major adverse tissue reaction. Mild recanalization was observed microscopically for both experimental and control microspheres. Zn-Si microspheres permit the definition of spatial distribution in a target tissue, consequently permitting the optimization, personalization and improvement of TAE techniques.

Advances in Degradable Embolic Microspheres: A State of the Art Review

Considerable efforts have been placed on the development of degradable microspheres for use in transarterial embolization indications. Using the guidance of the U.S. Food and Drug Administration (FDA) special controls document for the preclinical evaluation of vascular embolization devices, this review consolidates all relevant data pertaining to novel degradable microsphere technologies for bland embolization into a single reference. This review emphasizes intended use, chemical composition, degradative mechanisms, and pre-clinical safety, efficacy, and performance, while summarizing the key advantages and disadvantages for each degradable technology that is currently under development for transarterial embolization. This review is intended to provide an inclusive reference for clinicians that may facilitate an understanding of clinical and technical concepts related to this field of interventional radiology. For materials scientists, this review highlights innovative devices and current evaluation methodologies (i.e., preclinical models), and is designed to be instructive in the development of innovative/new technologies and evaluation methodologies.

Interventional Radiology in Canada: Current Challenges and Future Directions

OBJECTIVE We aim to define the practice of interventional radiology (IR) in Canada, barriers that have been faced by interventional radiologists, and ways in which the Canadian Interventional Radiology Association (CIRA) have attempted to address these issues. CONCLUSION IR has faced significant challenges in the Canadian setting. Recognizing the need to address these challenges, leaders in the field of IR in Canada founded the CIRA to serve as our national voice and lobby group.

Chapter 20:Glass Materials in Interventional Radiology and Interventional Oncology

Historically, the use of bioactive glasses has been largely devoted to orthopaedic and dental applications. However, the properties which may be derived from glass materials in medical applications is vast. In this chapter, the authors discuss the potential for new formulations of glass for applications in the field of interventional radiology and interventional oncology. This chapter will highlight the benefits, the potential, and the challenges, of developing new glass materials in this field of medicine. This chapter illustrates that this area of glass research is rich with opportunities to discover new formulations and applications for glass materials in medicine, discoveries which may lead to significant advances in the personalization, optimization and standardization of transarterial embolization procedures in areas of oncology and beyond.