Embolization agents-which one should be used when? Part 2: small-vessel embolization

Endovascular Embolization of Traumatic Vessel Injury Using N-butyl Cyanoacrylate: A Case Series

There is limited evidence of N-butyl cyanoacrylate (n-BCA) use in endovascular embolization of traumatic face and neck vessel injuries. We investigated the safety and effectiveness of n-BCA for this purpose. We retrospectively analyzed consecutive patients presenting to a Level 1 trauma center between April 2021 and July 2022. We included patients aged ≥ 18 years old with any vessel injury in the face and neck circulation requiring n-BCA embolization. The primary endpoint was n-BCA effectiveness defined as immediate control of active bleeding post-embolization. In total, 13 patients met the inclusion criteria. The median decade of life was 3 (IQR 3 - 5) with a male predominance (n = 11, 84.6%). Median Glasgow Coma Scale score on presentation was 15 (IQR 3-15). Eleven patients suffered gunshot wound injuries; two patients suffered blunt injuries. Injured vessels included facial artery (n = 6, 46.2%), buccal branch artery (n = 3, 23.1%), internal maxillary (n = 5, 38.5%), cervical internal carotid artery (n = 1, 7.7%), and vertebral artery (n = 1, 7.7%). All patients were treated with 1:2 n-BCA to ethiodol mixture with immediate extravasation control. No bleeding recurrence or need for retreatment occurred. One patient died in-hospital (7.7%). Patients were discharged to home (n = 8, 61.5%), day rehabilitation (n = 1, 7.7%), or acute rehabilitation (n = 3, 23.1%). One patient developed a right posterior cerebral artery infarct with hemorrhagic transformation. To our knowledge, this is the first study demonstrating the safety and effectiveness of n-BCA liquid embolism in traumatic vessel injuries, especially penetrating gunshot wounds.

A First-in-Human Trial of a New Aqueous Ionic Liquid Embolic Material in Distal Embolization Applications

PURPOSE

A prospective, single-arm, open-label, multicenter, first-in-human, early feasibility study was completed to evaluate the safety and performance of the GPX Embolic Device (Fluidx, Salt Lake City, Utah), a novel liquid embolic agent, for use in the peripheral vasculature when deep distal embolization is desired.

MATERIALS AND METHODS

The early feasibility study evaluated the use of the device in the peripheral vasculature. Enrollment consisted of 17 patients with diverse embolization needs requiring deep distal vessel/vessel bed occlusion. Technical success, freedom from adverse events (AEs), and handling/performance characteristics were assessed with follow-up at 30 days.

RESULTS

The trial enrolled 17 patients requiring distal vascular penetration of the embolic agent, including 7 with renal angiomyolipomas, 4 with renal cell carcinomas (primary and secondary), 4 with portal veins needing embolization, 1 with pelvic sarcoma, and 1 with polycystic kidney. In all cases (100%), technical success was achieved with target regions fully occluded on the first angiogram (taken immediately after delivery). Furthermore, the material received high usability ratings, as measured by a postprocedural investigator questionnaire. Most patients (15/17, 88.2%) were free from device-related severe AEs, and there were no unanticipated AEs during the study. Each patient completed a 30-day follow-up evaluation, and sites remained fully occluded in each case where imaging was available (6 [35.3%] of 17 patients had follow-up imaging where all sites were deemed occluded [100%] with a mean of 30.2 days after the procedure).

CONCLUSIONS

The results of this first-in-human, early feasibility study demonstrate that the GPX Embolic Device may provide safe and effective embolization for arterial or venous applications where deep distal penetration is desired.

Pelvic arteriovenous malformation (AVM) with recurrent hematuria: A case report

INTRODUCTION

Arteriovenous malformation (AVM) leads to a direct connection between arterial and venous networks, in which capillary branches are not involved. Pelvic AVM is a benign and rare condition causing severe pain, hematuria, and rectal or vaginal bleeding.

CASE PRESENTATION

A 36-year-old woman presented with five months history of hematuria. Her medical history was unremarkable, and laboratory findings were all within normal ranges. Abdominopelvic computed tomography (CT) scan revealed a vascular mass in the left lateral pelvis that extended to the bladder neck and was suggestive of an AVM. The patient underwent a laparotomy for the resection of AVM. The first angiography revealed an AVM in the left internal iliac artery. The patient underwent embolization with coil and gel foam. The second angiography revealed complete obstruction of the left internal iliac artery due to multiple coils and AVM of the right internal iliac artery (RIIA), embolized with glue and lipiodol. A week later, venography revealed another left iliac vein malformation embolized with foam sclerotherapy. Forty days later, the third angiography revealed another AVM in the right iliac artery, embolized with three vials of polyvinyl alcohol (PVA). Following two months of follow-up, the symptoms did not return.

DISCUSSION

The present study reported a rare case of recurrent pelvic AVM causing painless hematuria in a female patient. The lesion was treated with several angioembolization sessions.

CONCLUSION

Angioembolization is one of the main therapeutic options for AVM. Appropriate material should be precisely chosen for AVM embolization regarding the AVM's location, size, and condition.

Hybrid surgery of arteriovenous malformation and aneurysm of the sole

The study describes the successful treatment of a rare type of arteriovenous malformation (AVM) in the sole using hybrid surgery, which consists of open resection and embolization. Moreover, the possibility of utilizing ultrasound during examination in addition to angiography for the diagnosing of AVM of the sole is proposed.

Material characterization of GPX®: A versatile in situ solidifying embolic platform technology

Endovascular embolization is a minimally invasive procedure during which blood flow to targeted tissues is selectively occluded. The list of clinical indications for embolization continues to expand. Liquid embolic agents are injectable compositions that transition into a solid or semi-solid form when introduced into blood vessels. The mechanism that triggers the liquid-to-solid transition is a key distinguishing feature of liquid embolic agents. GPX is a waterborne liquid embolic agent comprising oppositely charged polyelectrolytes: polyguanidinum and inorganic polyphoshate. In situ solidification is driven by electrostatic condensation of the polyelectrolytes, triggered by ionic strength differentials. We report in vitro characterization of the material properties of GPX, it is in vivo effectiveness in acute animal studies, and its potential for chemoembolization. The viscosity of GPX can be varied over a wide range by adjusting the polyguanidinium MW and/or concentration. Formulation of GPX with either tantalum microparticles (30 wt%) or iodinated radiocontrast agents (300 mgI ml^-1) did not significantly change the flow behavior of GPX; the viscosity was independent of shear rate and remained within a clinically practical range (80-160 cP). Formulation of GPX with doxorubicin substantially increased viscosity at low shear rates and resulted in a power law dependence on shear rate. High contrast and effective vascular occlusion were demonstrated in both swine kidneys and rete mirabile. Contrast from iodinated compounds was temporary, dissipating within hours. The doxorubicin in vitro release profile was linear over 90 days. The results demonstrate that GPX is a versatile liquid embolic platform that can be formulated with a wide range of viscosities injectable at clinically practical flow rates, with either transient or permanent contrast, and that can provide prolonged zero-order delivery of doxorubicin to embolized tissues.

Evaluation of the safety and efficacy of transarterial sevelamer embolization in a rabbit liver cancer model: A challenge on the size rule for vascular occlusion

As the most efficient method to treat hepatocellular carcinoma in the immediate or advanced stage, transarterial chemoembolization (TACE) is coming into the era of microsphere (MP). Drug-eluting beads have shown their huge potential as an embolic agent and drug carrier for chemoembolization, but their sizes are strictly limited to be above 40 μm, which was considered to occlude vessels in a safe mode. microsphere smaller than 40 µm is easy to be washed out and transported to the normal liver lobe or other organs, causing severe adverse events and failed embolization. To determine whether sevelamer ultrafine particle (0.2-0.5 µm) is qualified as a safe and efficient embolic agent, we investigated the safety and therapeutic efficiency of transarterial sevelamer embolization (TASE) in the VX2 rabbit liver cancer model, aiming to challenge the "40 µm" rule on the selection criteria of the MP. In a four-arm study, blank bead (Callisphere, 100-300 µm), luminescent polystyrene microsphere (10, 100 µm), and sevelamer particle were transarterially administered to evaluate the threshold size of the MP size for intrahepatic or extrahepatic permeability. Another four-arm study was designed to clarify the safety and efficiency of preclinical transarterial sevelamer embolizationTASE tests over other techniques. Sham (saline), TASE, C-TACE, and D-TACE (n = 6) were compared in terms of serum chemistry, histopathology, and tumor necrosis ratio. In the first trials, the "40 µm" rule was detectable on the VX2 cancer model, but the regulation has no application to the new embolic agent as sevelamer ultrafine particles have not been found to leak out from the VX2 lesions, only found in the embolized vessels. Pathology proves that less viable tumor residue was found 2 weeks after the procedure, evidencing a better therapeutic outcome. No adverse events were found except for a short stress response. These results indicate that sevelamer is a safe and efficient embolic as an alternative to the current MP-based embolization therapy techniques.

X-ray Microtomography to Assess Determinants of In Vivo N-Butyl Cyanoacrylate Glubran®2 Polymerization: A Rabbit-Model Study

Although introduced decades ago, few cyanoacrylate glues have been approved for endovascular use, despite evidence of their usefulness, notably for complex procedures suchas hemostatic embolization. Indications include massive bleeding requiring emergent hemostasis and prevention of severe bleeding during scheduled surgery to remove a hypervascular tumor. Adding radiopaque Lipiodol Ultra Fluid® (LUF) modulates glue polymerization and allows fluoroscopic guidance, but few comparative in vivo studies have assessed the impact of the resulting change in glue concentration or of other factors such as target-vessel blood flow. In a rabbit model, we used ex vivo X-ray microtomography to assess the results of in vivo renal-artery embolization by various mixtures of N-butyl cyanoacrylate (NBCA), metacryloxysulfolane, and LUF. Overall, penetration to the superficial interlobular arteries was achieved in about two-thirds of cases and into the capillaries in nearly half the cases, while cast fragmentation was seen in slightly more than half the cases. Greater NBCA dilution and the blocked-blood-flow technique were independently associated with greater distality of penetration. Blocked-blood-flow injection was independently associated with absence of fragmentation, capillary penetration, a shorter cast-to-capsule distance, and higher cast attenuation. A larger mixture volume was independently associated with higher indexed cast ratio and deeper penetration. Finally, microtomography is an adapted tool to assess ex vivo distribution of glue cast.

Technical aspect in renal artery embolization in renal tumors: A case series

Introduction

Renal artery embolization aims to reduce blood loss during surgery. Various embolizing agents are available, each of which has its own indications appropriate for various vascular anatomy and renal pathology.

Presentation of case

We report three cases of renal artery embolization prior to surgical nephrectomy using vascular plug and other embolizing agents. In two cases, complete blood flow occlusion was achieved with minimal blood loss during the subsequent surgery. One case only achieved reduced blood flow, but subsequent nephrectomy and patient recovery was successful.

Discussion

Renal artery embolization prior to malignant mass resection is a well-known, potentially beneficial procedure. The rationale that supports this procedure is clear, but its reported outcome in the literature is still inconclusive. It is important to understand its benefits, complications, and pitfalls to achieve better outcome.

Conclusion

In our cases, renal artery embolization provided satisfactory reduction in bleeding during nephrectomy, and therefore has the potential to be employed as a standard procedure for future surgeries.

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Arterial embolization in renal pathology currently has no clinical guidelines

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The use of vascular plug in renal vascular pathology is feasible

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Careful consideration is needed regarding the choice of renal arterial embolization

Interventional Radiology Options after Visceral Surgery

Background

Postoperative management of patients undergoing visceral surgery can present challenging clinical situations with significant morbidity and mortality. Interventional radiological techniques offer quick, safe, and effective minimally invasive treatment options in the postoperative management of visceral surgery.

Summary

Most commonly done procedures include - but are not limited to - fluid or abscess drainage, biliary diversion, bleeding embolization, and re-canalization of a thrombosed vessel. While bleeding from side branches after hepatobiliary and pancreatic surgeries can be managed by coil embolization, the hepatic arterial injury should be managed by stent-graft placement. Hepatic venous complications can require a transhepatic or transjugular approach, whereas the transjugular intrahepatic portosystemic shunt approach has a higher clinical success rate in patients with portal vein thrombosis. Biliary leakages require multidisciplinary management, and interventional radiology can offer an efficient treatment, especially in patients with biliodigestive anastomosis.

Key Messages

Interventional radiology provides a broad spectrum of procedures in the management of patients with recent visceral surgery.

Clinical Outcomes Following Rectal Artery Embolisation for the Treatment of Internal Haemorrhoids: A Systematic Review and Meta-Analysis

OBJECTIVES

Haemorrhoidal disease (HD) is a common anorectal disorder which can substantially impair quality of life. Rectal artery embolisation (RAE) is a recently described technique for the management of HD, however, its clinical efficacy and safety are unclear at present. The objective of this systematic review and meta-analysis is to evaluate the clinical outcomes following RAE.

METHODS

The PubMed, MEDLINE and EMBASE databases were searched for studies specifying the management of haemorrhoids with RAE from January 2000 to October 2021. Primary outcomes were: French bleeding score (FBS), Visual analogue scale (VAS) for pain, general quality of life (QoL) score, and the Goligher prolapse score (GPS). Secondary outcomes were technical success, clinical success, postoperative complications, and technical outcomes. A random-effects meta-analysis was conducted. Study heterogeneity was evaluated, and sensitivity analysis was performed.

RESULTS

Thirteen eligible studies were identified including 381 patients. Rectal artery embolisation was associated with improvements in the FBS (mean difference [MD] 2.66; 95% confidence interval [CI] 2.10-3.23), VAS (MD 1.92; 95% CI 1.58-2.27) and QoL (MD 1.41; 95% CI 1.20-3.80), although the grade of internal haemerrhoids increased with uncertain clinical significance (MD 0.30; 95% CI 0.23-0.36). Technical success was achieved in almost all procedures (99%; 95% CI 94-100%) however clinical efficacy was lower (82%; 95% CI 73-89%). Procedural duration and radiation exposure were heterogeneous. No major complications occurred.

CONCLUSION

RAE demonstrates early clinical efficacy with low rates of peri-procedural complications or morbidity. RAE is a promising addition to the treatment options available for HD and warrants ongoing research.

Endovascular Embolisation of Pulmonary Arteriovenous Malformation Using Amplatzer Vascular Plugs

Pulmonary arteriovenous malformation (PAVMs) are abnormal communications between pulmonary arteries and veins. The rarity of their occurrence, coupled with the risks they pose, including brain abscess, embolic stroke, and myocardial infarction, mandates that they should not be overlooked in the differential diagnosis of patients presenting with haemoptysis, dyspnea, clubbing, cyanosis, hypoxemia, or epistaxis.

We present the case of a 41-year-old local female who presented to our hospital as an outpatient with decreased oxygen saturation (SpO₂) of 70%-80% for the past two years with a final diagnosis of PAVM. The initial baseline workup showed polycythemia with a hemoglobin level of 19 mg/dL and raised hematocrit. She had extensive workup in the past two years for her polycythemia including gene mutation testing and cardiac workup which all turned out normal. Her chest X-ray (CXR) showed right lung opacity which was initially considered to be infective but it did not respond to antibiotic treatment. Later on, a CT scan of the chest was performed and findings were typical of a large PAVM which had two feeding arteries. The patient was referred to a cardiothoracic surgeon who sent the patient to the interventional radiology section for endovascular management.

The embolization procedure was then performed and both feeders were successfully embolised. After the procedure, the patient's SpO₂ levels were restored to 95%-96%, and no post-procedure complications were noted.

Splenic embolization in trauma: results of a survey from an international cohort

PURPOSE

A questionnaire regarding splenic embolization in trauma was submitted to an international sample of IR faculty members, to compare their practice to the available recommendations.

METHODS

A 21 multiple-choice questionnaire was sent to an international cohort of 96 IR faculty. Questions included the initial patient evaluation, embolization materials and techniques, post-procedure management, availability of an institutional protocol, and use of guidelines.

RESULTS

For each question, there were from a minimum of 45 to a maximum of 52 responders: 94% require a CT with contrast prior to embolization, and 87% use the American Association for the Surgery of Trauma (AAST) scale to grade the splenic injuries. Embolization is performed across all values of the AAST scale. Of the patients with injuries of grade III or greater, embolization is primarily done for those patients who are hemodynamically stable. Unstable patients are embolized less frequently and primarily in cases in which the injuries are of a lower grade. Coils are the preferred material for proximal embolization (69%). Particles/Gelfoam is the preferred material for distal embolization (38%). In total, 63% administer intravenous antibiotics before the procedure and 15% administer intra-arterial antibiotics during the procedure. After embolization, follow-up imaging is recommended by 87%, antibiotics are administered regularly by 33%, clinical follow-up is recommended by 73%, and vaccination against encapsulated organisms is routinely recommended by 39%.

CONCLUSIONS

There is significant variability among a heterogeneous cohort of respondents. Available recommendations may not be sufficiently addressing the practice of splenic embolization.

The Role of Angioembolization in Hepatic Trauma

The liver is one of the most commonly injured solid organs in blunt abdominal trauma. Non-operative management is considered to be the gold standard for the care of most blunt liver injuries. Angioembolization has emerged as an important adjunct that is vital to the success of the non-operative management strategy for blunt hepatic injuries. This procedure, however, is fraught with some possible serious complications. The success, as well as rate of complications of this procedure, is determined by degree and type of injury, hepatic anatomy and physiology, and embolization strategy among other factors. In this review, we discuss these important considerations to help shed further light on the contribution and impact of angioembolization with regards to complex hepatic injuries.

Current Debates Regarding Optimal Patient Evaluation and Procedural Technique for Prostatic Artery Embolization

There are active debates surrounding patient evaluation and procedural techniques of prostate artery embolization. This review evaluates the available evidence on the value of urodynamics, the effect of prostate gland size, the benefits of pre- and intraprocedural cross-sectional imaging, the utility of a balloon-occlusion microcatheter, the differences among embolic particle sizes and types, and the merits of radial versus femoral arterial access.

Advances in Biomaterials and Technologies for Vascular Embolization

Minimally invasive transcatheter embolization is a common nonsurgical procedure in interventional radiology used for the deliberate occlusion of blood vessels for the treatment of diseased or injured vasculature. A wide variety of embolic agents including metallic coils, calibrated microspheres, and liquids are available for clinical practice. Additionally, advances in biomaterials, such as shape-memory foams, biodegradable polymers, and in situ gelling solutions have led to the development of novel preclinical embolic agents. The aim here is to provide a comprehensive overview of current and emerging technologies in endovascular embolization with respect to devices, materials, mechanisms, and design guidelines. Limitations and challenges in embolic materials are also discussed to promote advancement in the field.

In vivo evaluation of callispheres microspheres in the porcine renal artery embolization model

This study aimed to evaluate the operational performance, embolization effect and safety of CalliSpheres microspheres (CSM) in a porcine renal model. 24 healthy normal pigs were randomized into CSM group and Embosphere microspheres (ESM) group equally, and embolized with CSM or ESM in the lower pole of right kidneys, respectively. On D2, D7 and D28 after the operation, angiography and biochemistry examination were performed, and then the pigs were subjected to renal macroscopic and histopathological examination after euthanasia (4 pigs/group per each time point). The embolization was performed successfully in all pigs without obvious adverse events or deaths, and there was no difference in operation assessments (including number of embolized arteries, volume of injected microspheres and vessel recanalization rate) between CSM group and ESM group. After the operation, all pigs in CSM group and ESM group presented with renal necrosis, stasis and capsule exudation on D2 and D7, and capsule thickening, fibrosis and renal atrophy on D28, and there was no difference in these macroscopic or microscopic manifestations between two groups. For biochemistry indexes (including blood routine, coagulation function, liver function and renal function), most of them were similar between two groups at each time point. CSM embolizes porcine renal artery effectively and safely without obvious adverse events or deaths, which might be a good option for embolization therapy in clinical practices.

Precipitating hydrophobic injectable liquid (PHIL) embolic for the treatment of a uterine arteriovenous malformation: a technical report

OBJECTIVE

Uterine arteriovenous malformations (AVM) are unusual causes of vaginal bleeding. Although hysterectomy is the definitive treatment; uterine artery embolization (UAE) provides an alternative therapeutic option. This case presents a technical report of a uterine AVM treated successfully with transcatheter UAE using precipitating hydrophobic injectable liquid (PHIL) embolic agent.

CASE REPORT

A 41-year-old female, gravida 6, para 4, miscarriage 2, including a molar pregnancy 15 years prior, presented with massive per vaginal bleeding. Pelvic ultrasound demonstrated an acquired AVM as the underlying aetiology for her presentation. The patient underwent bilateral uterine arterial embolization. Four weeks later, there was nearly complete resolution of the AVM and the patient's menstrual cycle was restored 8 weeks after the procedure.

CONCLUSION

Uterine AVM can be treated safely and effectively with UAE using PHIL.

Impact of trivalent ions on the stability and cohesion of calcium polyphosphate coacervates for embolization applications

Polyphosphates (PPs) are of interest as temporary in situ setting embolic agents for which cohesive characteristics are vital. Trivalent ions Al³⁺ and Ga³⁺ were substituted into calcium PP up to 10 mol % for two PP chain lengths (degree of polymerization, D_p 200 and 9000) and the effect on the dissolution rate of the resulting coacervate was examined. High levels of trivalent ions were found to increase the dissolution rate, especially with aluminum (Al) where the coacervate with the greatest Al content (10 mol %) and larger D_p completely dissolved within the first few hours in tris(hydroxymethyl)aminomethane buffered saline. Conversely, small amounts of trivalent ions slowed the dissolution rate of the coacervates compared to those containing calcium only. The coacervate compositions determined to have the fastest and slowest ion release were evaluated for cohesion upon injection into a simulated blood vessel using a dual lumen needle. PPs with lower trivalent content had a higher coacervate yield overall, with 5% Ga and D_p 200 yielding the smallest proportion of coacervate particulates that could be implicated in unwanted distal embolization. However, further studies are required to evaluate the formation and duration of occlusions in vivo so that the PP composition can best be tailored to meet clinical requirements. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2638-2648, 2019.

Bioengineered in vitro Vascular Models for Applications in Interventional Radiology

The role of endovascular interventions has progressed rapidly over the past several decades. While animal models have long-served as the mainstay for the advancement of this field, the use of in vitro models has become increasingly widely adopted with recent advances in engineering technologies. Here, we review the strategies, mainly including bioprinting and microfabrication, which allow for fabrication of biomimetic vascular models that will potentially serve to supplement the conventional animal models for convenient investigations of endovascular interventions. Besides normal blood vessels, those in diseased states, such as thrombosis, may also be modeled by integrating cues that simulate the microenvironment of vascular disorders. These novel engineering strategies for the development of biomimetic in vitro vascular structures will possibly enable unconventional means of studying complex endovascular intervention problems that are otherwise hard to address using existing models.

Efficacy and safety of preoperative internal maxillary arterial embolization with gelfoam for nasopharyngeal angiofibroma

PURPOSE

To investigate the efficacy and safety of preoperative internal maxillary arterial embolization with gelfoam particles in patients with nasopharyngeal angiofibroma.

MATERIALS AND METHODS

We retrospectively reviewed a total of 27 consecutive patients with pathologically confirmed nasopharyngeal angiofibroma from August 2006 to September 2018. Of the 27 enrolled patients, 10 patients received surgical excision alone; 17 patients received preoperative internal maxillary arterial embolization followed by surgical excision. Embolic agents were gelfoam particles.

RESULTS

The mean volume of intro-operative blood loss was 385.3 ml in patients with preoperative arterial embolization, which was significantly lower than 1215.0 ml in the patients without preoperative arterial embolization (P < 0.001). The mean surgical time was shorter in patients with preoperative arterial embolization than in the patient without preoperative arterial embolization, but the difference had no statistical significance (205.0 vs 264.5 min, P = 0.064). Neurological complications such as facial palsy or vision loss or hemiplegia were not observed in patients with preoperative arterial embolization.

CONCLUSION

Internal maxillary artery embolization with gelfoam particles suffices to provide an effective and safe adjuvant procedure for surgical excision of nasopharyngeal angiofibroma.

Prophylactic absorbable gelatin sponge embolization for angiographically occult splenic hemorrhage

Nonoperative management of traumatic splenic hemorrhage includes the targeted administration of embolic agents. In certain instances where computed tomography angiography cannot exclude a bleed, prophylactic embolization with absorbable gelatin sponge has been used. In this retrospective case series review, we characterized the demographic data and clinical outcomes associated with 4 patients who underwent prophylactic transarterial splenic artery embolization after blunt abdominal trauma. Embolization was employed in cases where computed tomography angiography findings suggested at least a moderate splenic injury, and simultaneously where hemorrhage was not apparent during fluoroscopic angiography. Periprocedural hemodynamic status, technical success, and postoperative complications are discussed. The goal of this report was to discuss the safety and efficacy of prophylactic gelatin sponge embolization for occult splenic hemorrhage. In cases where a hemorrhagic site might be occult, this approach has the potential to minimize bleeding complications and the need for further intervention.

Bench-to-clinic development of imageable drug-eluting embolization beads: finding the balance

This review describes the historical development of an imageable spherical embolic agent and focuses on work performed in collaboration between Biocompatibles UK Ltd (a BTG International group company) and the NIH to demonstrate radiopaque bead utility and bring a commercial offering to market that meets a clinical need. Various chemistries have been investigated and multiple prototypes evaluated in search of an optimized product with the right balance of handling and imaging properties. Herein, we describe the steps taken in the development of DC Bead LUMI™, the first commercially available radiopaque drug-eluting bead, ultimately leading to the first human experience of this novel embolic agent in the treatment of liver tumors.

Successful percutaneous transgluteal embolization of a complex arteriovenous malformation feeding a hypogastric artery aneurysm

Pelvic arteriovenous malformation (AVM) is a rare condition mostly requiring a complex therapeutic strategy. The surgical approach is challenging and burdened by relatively high mortality and morbidity rates. No guidelines are available for the endovascular treatment of AVM because the literature is limited to small case series and case reports. We present a complex case of a pelvic AVM associated with an internal iliac artery aneurysm in a patient previously treated with a common to external prosthetic substitution for aneurysm and proximal ligation of internal iliac artery.

Biomaterials and Advanced Technologies for Hemostatic Management of Bleeding

Bleeding complications arising from trauma, surgery, and as congenital, disease-associated, or drug-induced blood disorders can cause significant morbidities and mortalities in civilian and military populations. Therefore, stoppage of bleeding (hemostasis) is of paramount clinical significance in prophylactic, surgical, and emergency scenarios. For externally accessible injuries, a variety of natural and synthetic biomaterials have undergone robust research, leading to hemostatic technologies including glues, bandages, tamponades, tourniquets, dressings, and procoagulant powders. In contrast, treatment of internal noncompressible hemorrhage still heavily depends on transfusion of whole blood or blood's hemostatic components (platelets, fibrinogen, and coagulation factors). Transfusion of platelets poses significant challenges of limited availability, high cost, contamination risks, short shelf-life, low portability, performance variability, and immunological side effects, while use of fibrinogen or coagulation factors provides only partial mechanisms for hemostasis. With such considerations, significant interdisciplinary research endeavors have been focused on developing materials and technologies that can be manufactured conveniently, sterilized to minimize contamination and enhance shelf-life, and administered intravenously to mimic, leverage, and amplify physiological hemostatic mechanisms. Here, a comprehensive review regarding the various topical, intracavitary, and intravenous hemostatic technologies in terms of materials, mechanisms, and state-of-art is provided, and challenges and opportunities to help advancement of the field are discussed.

An injectable shear-thinning biomaterial for endovascular embolization

Improved endovascular embolization of vascular conditions can generate better patient outcomes and minimize the need for repeat procedures. However, many embolic materials, such as metallic coils or liquid embolic agents, are associated with limitations and complications such as breakthrough bleeding, coil migration, coil compaction, recanalization, adhesion of the catheter to the embolic agent, or toxicity. Here, we engineered a shear-thinning biomaterial (STB), a nanocomposite hydrogel containing gelatin and silicate nanoplatelets, to function as an embolic agent for endovascular embolization procedures. STBs are injectable through clinical catheters and needles and have hemostatic activity comparable to metallic coils, the current gold standard. In addition, STBs withstand physiological pressures without fragmentation or displacement in elastomeric channels in vitro and in explant vessels ex vivo. In vitro experiments also indicated that STB embolization did not rely on intrinsic thrombosis as coils did for occlusion, suggesting that the biomaterial may be suitable for use in patients on anticoagulation therapy or those with coagulopathy. Using computed tomography imaging, the biomaterial was shown to fully occlude murine and porcine vasculature in vivo and remain at the site of injection without fragmentation or nontarget embolization. Given the advantages of rapid delivery, in vivo stability, and independent occlusion that does not rely on intrinsic thrombosis, STBs offer an alternative gel-based embolic agent with translational potential for endovascular embolization.

Complications of trans arterial embolization during the resuscitation of pelvic fractures

INTRODUCTION

Trans arterial embolization (TAE) can stem uncontrolled bleeding associated with pelvic fractures, but is associated with potential complications. This study investigated and compared the early to midterm complications in two patient cohorts: one who did and one who did not undergo TAE.

METHODOLOGY

The results of 14 patients who underwent TAE in the resuscitation phase, and then had their pelvic fractures managed non-operatively, the study group (Group 1), were compared with those of a control group (Group 2) of 14 patients matched for age, sex, injury and management, that did not undergo TAE. All patients were examined clinically and answered a questionnaire on bowel and urinary function, pain and limp. Gluteus medius structure and volume were assessed on MRI. The hip girdle muscle function was assessed using a hand held dynamometer, surface electromyography as well as quantitative gait analysis.

RESULTS

Seven patients in Group 1 (50%), but none in Group 2, had persistent urological dysfunctions, in the absence of any recognized previous pathology or urologic trauma at the time of injury. No gluteal muscle demonstrated fibrosis or fatty infiltration. The median gluteal muscle volume was not significantly decreased compared with the uninjured side in either group (P=0.421). The muscle strengths of gluteus maximus, gluteus medius, tensor fasciae latae and iliopsoas when compared to the uninjured side were significantly less in Group 1 compared to Group 2. However, no patient had a discernable limp and gait analysis showed no significant differences between the left and right sides in the study and control groups in the gluteal activation timing (p=0.171 and 0.354) and duration (p=0.622 and 0.435). There were no skin complications, and no patient reported any persistent bowel dysfunction.

CONCLUSION

TAE was associated with a high rate of persistent urological dysfunction. TAE could lead to decreased hip muscles strength, however this does not seem to affect gait.

Prognostic factors in endovascular treated pelvic haemorrhage after blunt trauma

Background

Angioembolization is the method of choice for treating haemorrhage after blunt pelvic trauma. The aim of this study was to determine technical factors related to endovascular procedures which might be related to patient outcome.

Methods

This retrospective study included 112 consecutive patients (40 women and 72 men; mean age 57.2 ± 20.0).

Results

There were age peaks at 43 and at 77 years. Patients over 65 years had mainly “low-energy” trauma; younger patients were more likely to have polytraumas. Younger patients were more severely injured and had more surgical interventions, larger haematoma volumes, lower Hb levels and required more transfusions than older patients. Women were older than men, had fewer surgeries and waited longer for an angiography (p < 0.05 each). Logistic regression analyses identified the injury severity score (ISS) as relevant for survival before age, haematoma volume and Hb. Propensity score analyses showed that in addition to the need for transfusions, haemoglobin, and haematoma volume, the length of the coils and the number of microcoils used were relevant (p < 0.05 each). The location of haemorrhage in peripheral parietal arteries (superior and inferior gluteal artery) was an influencing factor for re-angiographies, which were associated with considerably longer hospital stays of more than 40 days. Fewer particles had generally been used in these patients.

Conclusions

The use of too few coils and not using microparticles in angioembolization for pelvic haemorrhage are major influencing factors for the mortality or re-angiography rate. Special attention should be given to thorough peripheral embolization with microcoils, in particular for haemorrhage from the parietal branches of the internal iliac artery.

Transcatheter arterial embolization for traumatic mesenteric bleeding: a 15-year, single-center experience

PURPOSE

We aimed to assess the safety and effectiveness of transcatheter arterial embolization (TAE) for mesenteric bleeding following trauma.

METHODS

From 2001 to 2015, 12 patients were referred to our interventional unit for mesenteric bleeding following trauma, based on clinical decisions and computed tomography (CT) images. After excluding one patient with no bleeding focus and one patient who underwent emergency surgery, a total of 10 patients (male:female ratio, 9:1; mean age, 52.1 years) who underwent super selective TAE of visceral arteries were included in this study. Technical and clinical success, complications, and 30-day mortality rate were analyzed.

RESULTS

In 10 patients who underwent TAE, the types of trauma were motor vehicle collision (n=6), fall (n=2), assault (n=1), and penetrating injury (n=1), and the bleeding arteries were in the pancreaticoduodenal arterial arcade (n=4), jejunal artery (n=3), colic artery (n=2), and sigmoid artery (n=1). N-butyl-2-cyanoacrylate (NBCA) (n=2), microcoils (n=2), and combinations of NBCA, microcoils, or gelatin sponge particles (n=6) were used as embolic agents. Technical success was achieved in all 10 patients, with immediate cessation of bleeding. Clinical success rate was 90% (9/10), and all patients were discharged with no further treatment required for mesenteric bleeding. However, one patient showed rebleeding 10 days later and underwent repeated TAE with successful result. There were no TAE-related ischemic complications such as bowel infarction. The 30-day mortality rate was 0%.

CONCLUSION

Our clinical experience suggests that TAE used to control mesenteric bleeding following trauma is safe and effective as a minimally invasive alternative to surgery.

Review of the Development of Methods for Characterization of Microspheres for Use in Embolotherapy: Translating Bench to Cathlab

Therapeutic embolotherapy is the deliberate occlusion of a blood vessel within the body, which can be for the prevention of internal bleeding, stemming of flow through an arteriovenous malformation, or occlusion of blood vessels feeding a tumor. This is achieved using a wide selection of embolic devices such as balloons, coils, gels, glues, and particles. Particulate embolization is often favored for blocking smaller vessels, particularly within hypervascularized tumors, as they are available in calibrated sizes and can be delivered distally via microcatheters for precise occlusion with associated locoregional drug delivery. Embolic performance has been traditionally evaluated using animal models, but with increasing interest in the 3R's (replacement, reduction, refinement), manufacturers, regulators, and clinicians have shown interest in the development of more sophisticated in vitro methods for evaluation and prediction of in vivo performance. Herein the current progress in developing bespoke techniques incorporating physical handling, fluid dynamics, occlusive behavior, and sustained drug elution kinetics within vascular systems is reviewed. While it is necessary to continue to validate the safety of such devices in vivo, great strides have been made in the development of bench tests that better predict the behavior of these products aligned with the principles of the 3R's.

“Beyond saving lives”: Current perspectives of interventional radiology in trauma

Interventional radiology (IR) has become an integral part in the management of traumatic injuries. There is an ever-increasing role of IR in traumatic injuries of solid abdominal organs, pelvic and peripheral arteries to control active bleeding by therapeutic embolization or vascular reconstruction using stent grafts. Traditionally, these endovascular treatments have been offered to hemodynamically stable patients. However, in recent times endovascular approach has become preferable to surgery even in hemodynamically unstable patients with injury of surgically difficult-to-access sites. With shifting trends towards non operative management coupled with availability of the current state-of-the-art equipments, hardware and technical expertise, IR has gained an impeccable role in trauma management. However, due to lack of awareness and widespread acceptance, IR continues to remain an ocean of unexplored potentialities.

The role of coacervation and phase transitions in the sandcastle worm adhesive system

Sandcastle worms, Phragmatopoma californica (Fewkes), live along the western coast of North America. Individual worms build tubular shells under seawater by gluing together sandgrains and biomineral particles with a multipart, rapid-set, self-initiating adhesive. The glue comprises distinct sets of condensed, oppositely charged polyelectrolytic components-polyphosphates, polysulfates, and polyamines-that are separately granulated and stored at high concentration in distinct cell types. The pre-organized adhesive modules are secreted separately and intact, but rapidly fuse with minimal mixing and expand into a crack-penetrating complex fluid. Within 30s of secretion into seawater, the fluid adhesive transitions (sets) into a porous solid adhesive joint. The nano- and microporous structure of the foamy solid adhesive contributes to the strength and toughness of the adhesive joint through several mechanisms. A curing agent (catechol oxidase), co-packaged into both types of adhesive granules, covalently cross-links the adhesive and becomes a structural component of the final adhesive joint. The overall effectiveness of the granulated sandcastle glue is more a product of the cellular sorting and packaging mechanisms, the transition from fluid to solid following secretion, and its final biphasic porous structure as it is of its composition or any particular amino acid modification.

In vitro study of physical properties of various embolization particles regarding morphology before, during and after catheter passage

OBJECTIVE

To evaluate various embolization particles on their physical properties with special regard on morphological variability and elasticity.

METHODS

8 embolization particles (EmboCept®, Contour SE® Microspheres, Embosphere® Micorspheres 400 μm, 500 μm, 1300 μm, Embozene® Microspheres, DC Beads®, Embozene Tandem®) were evaluated and graduated from 1-6 microscopically due to morphologic changes in vitro before, during and after their catheter passage by 4 blinded reviewers. To facilitate comparison, microscopic images were provided with a scale.

RESULTS

All tested particles showed a homogenous shape and morphology before passage through the simulation catheter. During the passage all particles were elastically deformable, where necessary. After the catheter passage no loss of basic shape was seen. Changes in size were found in 5/8 particles. Grading of morphologic changes varied between mean value of 1.0 and 3.0. No complete destruction or loss of function was seen.

CONCLUSION

All tested embolization particles are, regarding their morphological properties in sense of homogenous shape and deformation after catheter passage, a safe treatment option. Tested in vitro no less of functionality regarding physical properties should be expected.

Percutaneous transcatheter embolisation of active haemorrhage following radiofrequency ablation of hepatocellular carcinoma

A 72-year-old woman with hepatitis C virus cirrhosis underwent a surveillance ultrasound examination which identified a new hepatic lesion. A workup triphasic CT examination demonstrated a 3.7 cm lesion at the hepatic dome with arterial enhancement and portal venous washout consistent with hepatocellular carcinoma. She subsequently proceeded for treatment with radiofrequency ablation (RFA). RFA was technically successful, but the patient became hypotensive and tachycardic postprocedure. A CT angiogram demonstrated active arterial intraperitoneal haemorrhage from the RFA site. The patient returned to the interventional suite for catheter angiography which confirmed the presence of active haemorrhage from the hepatic arterial branch supplying segment VIII. The bleeding vessel was selectively catheterised with a microcatheter, and successfully embolised with 250-355 µm polyvinyl alcohol particles.

Interventional Radiology in the Management of Visceral Artery Pseudoaneurysms: A Review of Techniques and Embolic Materials

Visceral artery pseudoaneurysms occur mostly as a result of inflammation and trauma. Owing to high risk of rupture, they require early treatment to prevent lethal complications. Knowledge of the various approaches of embolization of pseudoaneurysms and different embolic materials used in the management of visceral artery pseudoaneurysms is essential for successful and safe embolization. We review and illustrate the endovascular, percutaneous and endoscopic ultrasound techniques used in the treatment of visceral artery pseudoaneurysm and briefly discuss the embolic materials and their benefits and risks.

Water-Borne Endovascular Embolics Inspired by the Undersea Adhesive of Marine Sandcastle Worms

Transcatheter embolization is used to treat vascular malformations and defects, to control bleeding, and to selectively block blood supply to tissues. Liquid embolics are used for small vessel embolization that require distal penetration. Current liquid embolic agents have serious drawbacks, mostly centered around poor handling characteristics and toxicity. In this work, a water-borne in situ setting liquid embolic agent is described that is based on electrostatically condensed, oppositely charged polyelectrolytes-complex coacervates. At high ionic strengths, the embolic coacervates are injectable fluids that can be delivered through long narrow microcatheters. At physiological ionic strength, the embolic coacervates transition into a nonflowing solid morphology. Transcatheter embolization of rabbit renal arteries demonstrated capillary level penetration, homogeneous occlusion, and 100% devascularization of the kidney, without the embolic crossing into venous circulation. The benign water-borne composition and setting mechanism avoids many of the problems of current liquid embolics, and provides precise temporal and spatial control during endovascular embolization.

Lower GI bleeding: a review of current management, controversies and advances

PURPOSE

Lower gastrointestinal (GI) bleeding is defined as bleeding distal to the ligament of Treitz. In the UK, it represents approximately 3 % of all surgical referrals to the hospital. This review aims to provide review of the current evidence regarding the management of this condition.

METHODS

Literature was searched using Medline, Pubmed, and Cochrane for relevant evidence by two researchers. This was conducted in a manner that enabled a narrative review of the evidence covering the aetiology, clinical assessment and management options of continuously bleeding patients.

FINDINGS

The majority of patients with acute lower GI bleeding can be treated conservatively. In cases where ongoing bleeding occurs, colonoscopy is still the first line of investigation and treatment. Failure of endoscopy and persistent instability warrant angiography, possibly preceded by CT angiography and proceeding to superselective embolisation. Failure of embolisation warrants surgical intervention.

CONCLUSIONS

There are still many unanswered questions. In particular, the development of a more reliable predictive tool for mortality, rebleeding and requirement for surgery needs to be the ultimate priority. There are a small number of encouraging developments on combination therapy with regard to angiography, endoscopy and surgery. Additionally, the increasing use of haemostatic agents provides an additional tool for the management of bleeding endoscopically in difficult situations.

Aneurysmal bone cyst involving the c2 vertebra

A 9-year-old boy presented with a 3-month history of cervical pain, limited range of motion, and a palpable "bump" in his posterior neck. After treatment with antibiotics for presumptive adenopathy and progression of the palpable finding, radiographs were obtained.

A case-based approach to common embolization agents used in vascular interventional radiology

OBJECTIVE

The objective of this article is to familiarize the reader with the most commonly used embolic agents in interventional radiology and discuss an approach for selecting among the different embolic agents. This article reviews their properties and uses a case-based approach to explain how to select one.

CONCLUSION

A wide variety of embolic agents are available. Familiarity with the available embolic agents and selection of the most appropriate embolic agent is critical in interventional radiology to achieve optimum therapeutic response and avoid undesired, potentially disastrous complications such as nontarget embolization.

Transarterial embolization of intractable nasal and oropharyngeal hemorrhage using liquid embolic agents

INTRODUCTION

Intractable hemorrhage of the nasal or oropharyngeal cavities can be life threatening, and endovascular embolization is one of the few effective treatments for severe recurrent bleeds. Traditionally, embolic particles have been used for transarterial embolization.

OBJECTIVE

To investigate the safety and efficacy of a less commonly performed treatment-namely, feeding artery occlusion with liquid embolic agents.

METHODS

We retrospectively reviewed our neurointerventional database for patients who had undergone transarterial embolization for intractable nasal and oropharyngeal hemorrhage with Onyx, N-butyl-2 cyanoacrylate (n-BCA) glue, or both, at our institution over a 5-year period from 2008 to 2013.

RESULTS

Forty-six patients who underwent a total of 51 procedures met the inclusion criteria. Causes of hemorrhage included neoplasm n=35 (68.6%), trauma n=12 (23.5%), and idiopathic n=4 (7.9%). The bleeding was oropharyngeal in 66.7%, nasal in 29.4%, and 3.9% originated from both sites. Embolic agents used were n-BCA in 26 cases (51.0%), Onyx in 22 cases (43.1%), and both agents in three cases (5.9%). Mean total procedural time was 93.1 min (range 34-323 min), and mean fluoroscopy time was 39.1 min (10- 121 min). Mean follow-up time was 7.4 months (0.25-36 months). Five of the 46 patients (10.9%) required re-embolization and one (2.0%) rebled during the same hospital stay. One periprocedural cardiovascular adverse event occurred that was unrelated to the embolic agent used, but no other complications were seen.

CONCLUSIONS

Transarterial embolization with n-BCA or Onyx is a safe and effective treatment for patients with intractable nasal and oropharyngeal hemorrhage. Further prospective studies are warranted to confirm these findings.

A nanostructured synthetic collagen mimic for hemostasis

Collagen is a major component of the extracellular matrix and plays a wide variety of important roles in blood clotting, healing, and tissue remodeling. Natural, animal derived, collagen is used in many clinical applications but concerns exist with respect to its role in inflammation, batch-to-batch variability, and possible disease transfection. Therefore, development of synthetic nanomaterials that can mimic the nanostructure and properties of natural collagen has been a heavily pursued goal in biomaterials. Previously, we reported on the design and multihierarchial self-assembly of a 36 amino acid collagen mimetic peptide (KOD) that forms nanofibrous triple helices that entangle to form a hydrogel. In this report, we utilize this nanofiber forming collagen mimetic peptide as a synthetic biomimetic matrix useful in thrombosis. We demonstrate that nanofibrous KOD synthetic collagen matrices adhere platelets, activate them (indicated by soluble P-selectin secretion), and clot plasma and blood similar to animal derived collagen and control surfaces. In addition to the thrombotic potential, THP-1 monocytes incubated with our KOD collagen mimetic showed minimal proinflammatory cytokine (TNF-α or IL-1β) production. Together, the data presented demonstrates the potential of a novel synthetic collagen mimetic as a hemostat.

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.

Successful use of transcatheter embolisation in an emergent life-threatening situation of bleeding from uterine arteriovenous malformation

A 27-year-old G3P1 presented to the gynaecology emergency department with heavy vaginal bleeding for 16 days. Transvaginal ultrasound showed vascular cystic spaces in the myometrium raising a suspicion of choriocarcinoma. However, β-human chorionic gonadotrophin (β-hCG) was negative in both the urine and serum. Angiography confirmed the rarer diagnosis of uterine arteriovenous malformation (AVM). Successful abolition of the AVM was achieved by transcatheter embolisation with sequential use of polyvinyl alcohol particles, gel foam pledgets and platinum coils.