Grundlagen der Embolisation und anderer verschließender Verfahren

Vascular embolizations are complex and sophisticated procedures and can be a powerful alternative or useful adjunct to surgery in many clinical situations. Hemorrhage, vascular malformations, and tumors are the main indications for embolization procedures. Establishing the correct indication for intervention as well as the proper embolic agent and the most suitable catheterization technique requires advanced knowledge in interventional radiology, and an interdisciplinary approach is a prerequisite. A broad spectrum of microcatheters and embolization materials is available for these therapies. The desired level of occlusion and the individual vascular territory determine the choice of mechanical devices, particles, or liquid substances. Sclerosing agents and thrombin are used in special situations such as varicoceles and pseudoaneurysms.     

Embolization with detachable balloons--applications outside the head.

Detachable balloons, although widely used as an embolization material in neurovascular work, are rarely used outside the head. Yet they offer distinct advantages over other methods of embolization in certain situations. They can effect an instant and precise occlusion of large arteries and fistulae and unlike any other embolization technique the occlusion is reversible until the balloon is finally detached. In addition, they can be floated out to distal locations inaccessible with more conventional catheter techniques. They are inflated with contrast medium or silicone monomers. Large arteries and arteriovenous fistulae (AVFs) are best suited to balloon embolization where embolization distal to the fistula resulting in parenchymal infarction is not indicated. Thirteen patients underwent 14 detachable balloon embolizations. Eleven had large AVFs (4 coronary AVFs, 4 Blalock-Taussig shunts, 2 vertebro-vertebral fistulae and 1 renal AVF) and three had large arteries (2 aorto-pulmonary collaterals in one patient and 1 innominate artery pseudo-aneurysm). Twelve of these embolization procedures were successful and there were no complications. The two failures were due to inability to pass the balloon catheter around an acute angle in the introducer catheter and to early deflation. These cases illustrate a wide range of situations where balloon embolization may be used successfully. Continued refinement and improvement in the technique will allow expansion of the indications for non-neurological balloon embolization.     

C-Arm-CT zur Planung und Steuerung extrahepatischer Embolisationen

Interventional radiological vascular embolizations are complex procedures that require exact imaging of the target region to facilitate safe and effective treatment. The purpose of this paper is to present the technique and feasibility of flat detector C-arm computed tomography (C-arm CT) for control and guidance of extrahepatic abdominal embolization procedures. C-arm CT images can provide important information on both vascular and cross-sectional anatomy of the target region, help in determining therapy endpoints and provide follow-up during and immediately after the abdominal interventions.The cases presented demonstrate that C-arm CT images are beneficial for abdominal embolization procedures and facilitate precise treatment.     

Nierentumorembolisation

Today the relevance of renal tumor embolization is not determined only by the technical and clinical success of the method. Progress in diagnosis of early stages of renal carcinomas as well as the improvement of both surgical techniques and anesthetic procedures have lead to a change in the selection of patients for embolization. Preoperative embolization of advanced renal cell carcinomas with tumor thrombus into the vena cava or of T4 tumors is now an established clinical procedure. The complete occlusion of the vascular bed of the tumors leads to a considerable reduction in intraoperative blood loss and to simplification of the surgical preparation. By using Ethibloc for embolization, palliation of a hemorrhage or of tumor-related pain in inoperable patients is usually successful. Although local control of the tumor disease, including complete tumor ablation, is achieved by embolization, the median survival rate of our palliatively embolized patients is only 3.5 months. This short life expectancy in the group of inoperable patients has to be acknowledged individually in patients considered for palliative embolization who are free of symptoms related the tumor.     

Initial Clinical Experience Using the Amplatzer Vascular Plug

Background and purpose The Amplatzer Vascular Plug (AVP) is a self-expanding nitinol wire mesh vascular embolization device derived from the Amplatz septal occluder. We assessed the results of vascular embolization obtained using the AVP. Methods A retrospective review was carried out of 23 consecutive cases of vascular embolization using the AVP in a variety of different clinical settings. The AVP was chosen to have a diameter approximately 30–50% greater than the target vessel. The device was delivered via an appropriately sized guide catheter and was released when satisfactorily positioned. Additional embolic agents were used in some cases. Results All target vessels were successfully occluded with no device malpositioning or malfunction. In 14 (61%) patients the AVP was the sole embolic material. In the remaining patients additional agents were used, particularly in preoperative embolization of highly vascular renal tumors. The AVP does not cause instantaneous thrombosis and in high-flow situations thrombosis typically takes up to 15 min. Conclusion The AVP is a safe, effective embolization device that provides a useful adjunct to the therapeutic armamentarium. It is particularly suited to the treatment of short high-flow vessels where coil migration and catheter dislodgment might occur. In the majority of cases no additional embolic agents are necessary but it may take up to 15 min for complete thrombosis to occur.     

Preoperative embolization of the head and neck: indications, patient selection, goals, and precautions

Preoperative embolization was performed in 39 patients with 44 paragangliomas of the head and neck. Because of their complex vascular supply and their relation to vital structures such as the internal carotid artery and the lower cranial nerves, paragangliomas of the temporal bone represent challenging lesions to both the neuroradiologist and the otoneurosurgeon. Detailed classification by high-resolution CT and recognition of the multi- or monocompartmental vascular composition and of dangerous situations by selective angiography are essential prerequisites for safe and effective devascularization of paragangliomas of the temporal bone. Major complications that may occur if embolic material reaches intraaxial vessels through anastomoses between external carotid artery branches and the internal carotid and/or the vertebral artery can be avoided with the use of specific precautionary techniques. Palsies of the facial and lower cranial nerves can also be avoided if reabsorbable material is used for embolization of vessels supplying cranial nerves in asymptomatic patients. In selected cases with significant supply from the internal carotid artery, special interventional techniques, including embolization of the pericarotid tumor portion through the caroticotympanic artery and pre- or peroperative balloon occlusion of the petrous internal carotid artery, allow radical removal of extensive paragangliomas of the temporal bone. Techniques and selection of materials for embolization of carotid body, vagal body, and other paragangliomas of the head and neck mainly depend on the vascular composition of the tumor and on the specific vascular territory in which the tumor is located. In this series, preoperative embolization significantly improved surgical conditions of paragangliomas of any location in the head and neck and proved to represent an essential prerequisite for successful surgery of extensive paragangliomas of the temporal bone.     

弹簧圈血管内栓塞颅内动脉瘤危急事件中支架的应用

目的 探讨在血管内弹簧圈栓塞颅内动脉瘤过程中出现弹簧圈移位、突出或脱出和解旋等危急事件的原因及支架应用的价值.方法 回顾性分析12例弹簧圈栓塞颅内动脉瘤出现危急事件的病例,其中9例为宽颈动脉瘤;10例出现动脉瘤破裂出血;2例动脉瘤最大径为5 ～ 12 mm,7例为3 ～ 5 mm,3例＜ 3 mm;造影和临床随访超过1...     

神经介入手术中患者峰值皮肤剂量水平研究

目的 获得神经介入手术中患者峰值皮肤剂量数据（PSD）,评估患者确定性效应发生风险。方法 使用Gafchromic XR RV3胶片采集北京市某三级甲等医院神经介入手术患者的峰值皮肤剂量,主要研究血管栓塞术、血管成形术、血管造影术等3种常见的神经介入手术。使用Epson Expression 10000XL扫描仪扫描胶片,利用ImageJ和Film QA Pro^TM 2014软件测量和分析胶片。结果 共采集49例神经介入手术患者的峰值皮肤剂量数据,包括血管栓塞术23例、血管成形术14例、血管造影术12例。PSD ≥ 2 Gy患者20例,其中血管栓塞术15例,血管成形术5例。血管造影术患者的PSD均<2 Gy。部分神经介入手术患者的峰值皮肤剂量超过国际放射防护委员会（ICRP）第118号报告中的确定性效应剂量阈值。结论 神经介入手术存在发生确定性效应的风险,建议针对风险较高的患者进行随访观察,及时了解其辐射损伤情况和后续诊治。     

Guidelines on the use of gelatin sponge particles in embolotherapy

Gelatin sponge (GS) is one of the most widely used embolic agents in interventional procedures. There are four commercially available GS products in Japan; however, the endovascular use of Gelfoam and Spongel is off-label, and Gelpart can only be used for hepatic artery embolization and Serescue can only be used for hemostasis of arterial bleeding. GS has been used for a variety of clinical indications, mainly tumor embolization and stopping massive arterial bleeding. The optimal size and preparation procedure of GS particles differs slightly for each clinical indication. In addition, there is a risk of ischemic and/or infectious complications associated with GS embolization in various situations. Therefore, radiologists should be familiar with not only the preparation and handling of GS particles, but also the disadvantages and potential risks, in order to perform GS embolization safely and effectively.     

In vivo evaluation of iophendylate-cyanoacrylate mixtures.

Cyanoacrylate glue is a rapidly polymerizing agent used for vascular embolization. Polymerization occurs when the glue comes into contact with ions in the blood or on the vascular endothelium. Mixing iophendylate with cyanoacrylate causes slowing of polymerization, allowing flow-directed embolization into the nidus of an arteriovenous malformation (AVM) or the central neovascularity of a tumor or hemangioma. The authors attempted to define the relationship between the iophendylate-glue ratio and polymerization time with an in vivo swine model. In this model, glue setup occurred much more rapidly than predicted on the basis of in vitro studies. This appeared to be due to glue polymerizing on the endothelium at vessel bifurcations and at areas of acute angulation or marked vessel narrowing. On the basis of these data, the authors substantially increased the iophendylate-glue ratio in their most recent AVM embolization procedures and achieved nidus occlusion in each case. With use of the authors' guidelines, it is possible to achieve optimal distal flow-directed embolization with cyanoacrylate.     

Interventional radiology of the extracranial head and neck

The topic of interventional radiology of the extracranial head and neck is reviewed. Knowledge of functional vascular anatomy and recognition of the “dangerous anastomoses” between the external carotid artery and the intracranial circulation are stressed. Technical aspects of embolization are surveyed. The authors' approach to some of the more common lesions such as paragangliomas, congenital vascular lesions, epistaxis, juvenile angiofibromas, and arteriovenous fistulas are described. Illustrative cases are presented. Proper training and experience are needed in order to safely and effectively perform embolization procedures of the head and neck.     

Hemobilia: comparison of diagnostic technics. Considerations on 14 patients

Fourteen cases of hemobilia of traumatic (six), vascular (six) or neoplastic (two) origin were reviewed. Eleven patients obtained correct diagnosis only be integration of at least two diagnostic procedures out of Ultrasonography, Computed Tomography, arteriography and cholangiography. Although US and CT are extremely useful as screening procedures, correct diagnosis should be only possible by integration of more diagnostic technics. Arterial embolization represents a successful alternative to surgical intervention; moreover US may also be helpful for follow-up of treated patients.     

Trends in Percutaneous Embolization Procedures by Radiologists and Other Specialists

PurposeTo evaluate utilization trends in percutaneous embolization among radiologists and nonradiologist providers.Materials and MethodsThe nationwide Medicare Part B fee-for-service databases for 2005–2016 were used to evaluate percutaneous embolization codes. Six codes describing embolization procedures were reviewed. Physician providers were grouped as radiologists, vascular surgeons, cardiologists, nephrologists, other surgeons, and all others.ResultsThe total volume of Medicare percutaneous embolization procedures increased from 20,262 in 2005 to 45,478 in 2016 (+125%). Radiologists performed 13,872 procedures in 2005 (68% of total volume) and 33,254 in 2016 (73% of total volume), a 140% increase in volume. While other specialists also increased the number of cases performed from 2005 to 2016, radiologists strongly predominated, performing 87% of arterial and 30% of venous procedures in 2016, more than any other single specialty. In 2014 and 2015, a sharp increase in venous embolization cases performed by nonradiologists preceded a sharp decrease in 2016, likely the result of complicated billing codes for venous procedures. Radiologists maintained a steady upward trend in the number of cases they performed during those years.ConclusionsThe volume of percutaneous embolization procedures performed in the Medicare population increased from 2005 to 2016, reflecting a trend toward minimally invasive intervention. In 2016, radiologists performed nearly 10 times more arterial embolization procedures than the second highest specialty and more venous embolization procedures than any other single specialty.     

The vascular patient--diagnosis and minimally invasive therapy. Which technique for what illness?

The non-invasive imaging modalities, color coded duplex sonography (CCDS), magnetic resonance tomography (MRT), and computed tomography (CT), have pushed conventional angiography out of most diagnostic fields. The experienced user will achieve fast, reliable answers with CCDS in dedicated clinical settings. MRT as well as CT are concurring imaging modalities for the most appropriate diagnostic answer. Not only pure image quality, but also patient management, and availability play a major role. Catheter based angiography will in the future still play a role in mesenteric ischemia (non occlusive disease) and for imaging of very small vessel pathology, e.g. on panarteritis nodosa. At the moment, peripheral leg run-offs are still best performed with conventional angiography, nevertheless, MR as well as CT seem to have the ability to perform diagnostic procedures. Ongoing studies will allow a solid judgement in the near future. The true value of catheter angiography is in the direct assessment, planning, and performance of interventional procedures, e.g. catheter based obliteration or revascularization. Implantation of stent devices and a whole range of different mechanical and pharmacological revascularization procedures have improved the interventional management of vascular stenoses and occlusions. The interventional radiologist is treating physician in the classical sense in this setting. Acute bleeding episodes, e.g. in the brain, thorax, abdomen, or pelvis, are best imaged with computed tomography. Conventional angiography still plays a major diagnostic and therapeutic role in bleeding into preformed cavities, such as the bile ducts or the intestine. In this setting, all available information including CT scans should be valued. For complex therapeutic regimens in oncology or in pure palliative situations, angiographic diagnosis followed by embolization and/or ablation therapy is established.     

Embolization of high-flow craniofacial vascular malformations with onyx

BACKGROUND AND PURPOSE: Various techniques and materials have been used for the endovascular treatment of craniofacial high-flow arteriovenous vascular malformations, because their rarity precludes standardization of their treatment. The aim of this retrospective review is to assess Onyx as the primary embolic agent in the treatment of these vascular malformations. MATERIALS AND METHODS: Six patients with arteriovenous fistulas and 3 with arteriovenous malformations (AVMs) of the head and neck region were treated with intra-arterial (IA)/direct percutaneous injections of Onyx. Adjunctive maneuvers used during embolization included external compression of the arterial feeders or venous outflow (6 patients), balloon assist (4 patients), and direct embolization of the draining vein remote to the fistula site (1 patient). n-butyl-2-cyanoacrylate (n-BCA) was used in addition to Onyx for rapid induction of thrombosis in a large venous pouch (1 patient) and for cost containment purposes (1 patient). Four patients were treated surgically after the embolization. RESULTS: There were no neurologic complications secondary to the embolization procedure. The arteriovenous shunt was eliminated in all of the fistulous lesions and 2 of the 3 AVMs. The embolization was incomplete in 1 patient with a large AVM who declined further endovascular or surgical procedures. Untoward events included 2 instances of catheter entrapment (of 9 IA injections), blackish skin discoloration necessitating surgical revision in 1 patient, and difficulty of balloon deflation/wire withdrawal during a balloon-assisted embolization. CONCLUSION: Onyx appears to be a safe and effective liquid embolic agent for use in the treatment of craniofacial high-flow vascular malformations with distinct advantages and disadvantages compared with n-BCA.     

Nonfunctioning Renal Allograft Embolization as an Alternative to Graft Nephrectomy: Report on Seven Years’ Experience

PURPOSE: Graft nephrectomy is the treatment of choice in patients with graft intolerance syndrome, but it is associated with high morbidity and mortality rates. Renal vascular embolization has been suggested as a possible alternative. The aim of this study was to evaluate the efficacy and safety of arterial embolization of these nonfunctioning transplanted kidneys. METHODS: Twenty-six transplanted kidneys in 25 patients with irreversible renal graft rejection and graft intolerance who underwent arterial embolization at our center from August 1994 to April 2001 were analyzed for procedural success and long-term outcome. Embolization was performed with absolute alcohol or with polyvinyl alcohol (Ivalon) and coils. RESULTS: Twenty-four of the 26 (92%) procedures were technically successful, but in one patient only partial occlusion of one of two renal arteries was achieved, and in another the renal artery was already completely occluded. There were two major complications: emphysematous pyelonephritis necessitating nephrectomy and groin abscess that was drained. Follow-up ranged from 8 to 84 months. Clinical success was achieved in 24 of the 26 procedures (92%), and only in one patient did embolization fail to relieve the symptoms, and nephrectomy was performed 3 months later. CONCLUSION: Renal vascular embolization is a simple, safe and effective technique for the treatment of nonfunctioning renal allografts associated with graft intolerance syndrome. We suggest that it be considered the treatment of choice.     

Extracranial vascular angiography

Noninvasive procedures (ultrasound, CT, and MRI) are increasingly valuable in the diagnosis of diseases of the head and neck. Angiography, however, is still essential in the demonstration of vascular pathology, including the preoperative evaluation of vascular neoplasms. Through angioplasty and embolization techniques, angiography also plays a leading role in the treatment of arteriosclerotic vascular disease, vascular malformations, and vascular neoplasms.     

Management of visceral artery embolization using 0.010-inch detachable microcoils

Transcatheter coil embolization is used primarily to treat arterial hemorrhages, tumors, aneurysms, and vascular malformations. However, conventional microcatheter systems cannot always be employed in difficult cases. In this technical note, we describe how small-diameter primary coils and microcatheter tips that are thinner than normal can be used to increase the safety and reliability of coil embolization.Transcatheter embolization can be performed with the aid of coils, n-butyl cyanoacrylate, detachable balloons, gelatin sponges, polyvinyl alcohol particles, and other embolic materials (e.g., embospheres). Usually, the diameter of the primary coil is 0.018–0.035 inches, and the catheter tip size is 2.0–5.0 F. Transcatheter embolization occasionally requires superselective catheterization, and embolization of only a short segment, to ensure successful endovascular treatment. In some instances, the target arteries may be very thin, and extensively twisted and winding. Other patients may require embolization of short segments and/or tight packing of embolization materials, to prevent development of complications such as organ ischemia or infarction. In this technical note, we describe cases requiring ultraselective and/or short-segment embolization. We used microcoils that were thinner than normal, and small-tipped microcatheters, to treat such patients. Our experience supports the use of these materials. The procedures are technically feasible and are clinically effective alternatives to conventional transcatheter embolization.     

Internal iliac artery embolization before endovascular repair of aortoiliac aneurysms with a nitinol vascular occlusion plug

PURPOSE: To evaluate the acute and midterm effectiveness of a novel vascular occlusion device for embolization of the internal iliac artery (IIA) before endovascular repair of aortoiliac aneurysms. MATERIALS AND METHODS: Between March 2005 and April 2006, nine men (mean age, 75 years +/- 5; range, 66-83 y) with aortoiliac aneurysms underwent bifurcated endovascular stent-graft procedures. All these patients were referred specifically for embolization. Pre- and perioperatively, eight patients underwent unilateral embolization and one underwent bilateral embolization of the IIA to prevent type II endoleak. Via a contralateral femoral approach with a 6-F or 8-F sheath, the embolization procedure was performed with an Amplatzer Vascular Plug, a self-expandable cylindrical device consisting of a nitinol-based wire mesh. Technical success, clinical outcome, and complications were evaluated. Follow-up at 3, 6, and 12 months was performed with clinical and radiologic examinations. RESULTS: IIA embolization was technically successful in all cases and no procedure-related complications occurred. Imaging at discharge and at 3-, 6-, or 12-month follow-up was accomplished in all nine patients. Control computed tomography and magnetic resonance angiography did not reveal retrograde perfusion of the aneurysmal sac, ie, type II endoleak. Three of nine patients (33.3%) reported symptoms of buttock claudication that did not resolve completely. Clinical symptoms such as bowel ischemia or sexual dysfunction were not observed. CONCLUSIONS: The midterm results of this study suggest that preoperative IIA embolization with a nitinol vascular occlusion plug during endovascular treatment of aortoiliac aneurysms is safe and effective.     

Delayed venous occlusion following embolotherapy of vascular malformations in the brain.

PURPOSE: To describe the nature and features of delayed venous thrombosis following embolization of arteriovenous fistulae. METHODS: Retrospective review of the available clinical history, details of embolization procedures, and results of follow-up angiography were carried out on all embolization procedures performed on high-flow vascular malformations of the brain done at our institution since 1987. RESULTS: Four patients were identified who had delayed (greater than 1 week) venous thrombosis/occlusion after embolization of the malformation associated with neurologic complications. Two patients had arteriovenous fistula and two had vein-of-Galen malformations. These patients had no untoward embolization of the venous outlet as a cause of the venous occlusion. CONCLUSIONS: It is postulated that thrombosis in the arteriovenous fistula group was induced by conversion (due to embolization) of a patulous high flow venous outlet into a slow flow system; in the vein-of-Galen group, the occlusion was thought to be due to high-flow venopathy.