Embolization of peripheral high-flow arteriovenous malformations with Onyx.

PURPOSE: The aim of this study was to report our experience in embolization of high flow peripheral arteriovenous malformations (AVMs) with Onyx. MATERIAL AND METHODS: Nineteen patients (10 men, 9 women) with peripheral high-flow AVMs who were treated with arteruial embolization using Onyx were retrospectively included. AVMs were located in the head and neck (6), extremities (5), chest (2), kidney (2), uterus (2), pelvis (1) and parietal (1). In 13 patients, embolization was done using Onyx only. One patient underwent embolization by direct puncture, the others by transarterial approach. Embolization was performed in one or multiple sessions (up to 5). A total of 28 sessions were performed. Follow-up was performed with a delay between 10 and 34 months. RESULTS: Technical success was achieved in all patients. Complete devascularization was obtained in 12 patients. Surgical excision was performed in 9 patients. Non-target Onyx embolization was not observed. One patient developed stroke. In 1 patient microcatheter fracture occured. One patient presented severe pain and bradycardia during the procedure that disappeared shortly after. One patient had persistent but less frequent epistaxis after embolization. Another patient had persistent pain without improvement. One patient was lost to follow-up. Other patients were free of symptoms on follow-up. CONCLUSIONS: Embolization with Onyx® is an interesting option for management of peripheral high-flow AVMs either preoperatively or as a single treatment.

Transcatheter arterial embolization with ethylene vinyl alcohol copolymer (Onyx) for the treatment of hemorrhage due to uterine arteriovenous malformations.

PURPOSE: The purpose of this study was to evaluate the effectiveness of ethylene vinyl alcohol copolymer (Onyx) as a single embolic agent for percutaneous arterial treatment of hemorrhage due to uterine arteriovenous malformations (AVMs). MATERIALS AND METHODS: Twelve women (mean age, 33 years) with metrorrhagia due to uterine AVMs who were treated by percutaneous arterial embolization using Onyx as a single embolic agent were retrospectively included. The diagnosis of uterine AVM was suggested by pelvic ultrasound and/or magnetic resonance imaging findings and further confirmed by angiography. Clinical files and angiographic examinations were reviewed for angiographic findings, technical and clinical success, procedure complication and further pregnancies. Clinical success was defined by absence of metrorrhagia at 1 month following embolization. RESULTS: Sixteen arterial embolization procedures were performed. Angiographically, 6 women had high flow AVM and 6 had low flow AVM. The rate of technical and clinical success was 92% (11/12 patients). One woman with early repeat hemorrhage underwent two embolization procedures and further hysterectomy. No severe complications were observed after embolization. Three women (3/12; 25%) became pregnant following embolization including one full term pregnancy. CONCLUSION: In women with metrorrhagia due to AVM, arterial embolization with Onyx is effective and safe. Additional research is needed to confirm the possibility of future pregnancy after Onyx embolization.

Preclinical study on an animal model of a new non-adhesive cyanoacrylate (Purefill®) for arterial embolization.

PURPOSE: The goal of this study was to assess the distal dispersion, the adhesion strength to catheter, the vascular toxicity and the ability in excluding embolized vessels using Purefill® (α-hexil-cyanoacrylate) as embolic material, which is a new high purity cyanoacrylate and compare these results with those obtained with N-butyl-2-cyanoacrylate (Histoacryl®) and a mixture of N-butyl-2-cyanoacrylate and methacryloxysulfolane. MATERIAL AND METHODS: In six pigs, the right rete mirabile (RM) and right renal arteries were embolized with α-hexil-cyanoacrylate, and the left rete mirabile and left renal artery were embolized with N-butyl-2-cyanoacrylate and N-butyl-2-cyanoacrylate+Methacryloxysulfolane for comparison. One minute after glue injection through the microcatheter, displacements of the kidney and the pharyngeal artery were measured on angiographic images, before exercising any traction and during catheter pulling, when the forces were maximal. Displacement was measured in terms of distance (mm) with respect to renal pedicles and in terms of angle (°) with respect to the rete. After acute embolization (4 pigs) or three-month follow-up (2 pigs), the kidneys and the RM were removed and further analysed using computed tomography and histopathological examination. RESULTS: Similar short and long-term embolic efficacies were observed with the three glues. The mean displacement distances of renal pedicles were 2.6mm for α-hexil-cyanoacrylate, 22.6mm for N-butyl-2-cyanoacrylate and 19.8mm for N-butyl-2-cyanoacrylate+Methacryloxysulfolane (P=0.021). The mean angles of displacement of the ascending pharyngeal arteries were for 12.2° for α-hexil-cyanoacrylate, 23.5° for N-butyl-2-cyanoacrylate and 30° for N-butyl-2-cyanoacrylate+Methacryloxysulfolane (P=0.070). Histopathologically, findings were similar for the three glues, immediately and 90 days after embolization. CONCLUSION: α-hexil-cyanoacrylate has occlusive efficacy in the short and long term similar to those of N-butyl-2-cyanoacrylate and N-butyl-2-cyanoacrylate+Methacryloxysulfolane. In addition, histopathological changes are similar with the three glues immediately or 90 days after embolization. Conversely, α-hexil-cyanoacrylate results in a reduced angle and distance of displacement compared to the other two glues, assumably reflecting a limited adhesive strength.

Editor's Choice - Minimizing Radiation Exposure During Endovascular Procedures: Basic Knowledge, Literature Review, and Reporting Standards.

CONTEXT: Endovascular procedures, requiring X-ray guidance, are commonly performed in vascular surgery. X-ray exposure is associated with biological risks for both patients and physicians. Medical X-ray use must follow "as low as reasonably achievable" (ALARA) principles, which aim at using the lowest radiation exposure to achieve a procedure safely. This is underlined by European and international recommendations that also suggest that adequate theoretical and practical training is mandatory during the initial education of physicians. However, the content of this education and professional practices vary widely from one country to another. OBJECTIVE: This review aims to summarize the basic knowledge required for vascular surgeons on X-ray physics and image production. METHODS: A panel of endovascular therapists (vascular surgeons and radiologists) and physicists dedicated to X-rays was gathered. International recommendations were summarized. A literature review was performed via MEDLINE to identify studies reporting dosages of common endovascular procedures. RESULTS: The different mechanisms inducing biological risks, and the associated potential effects on health, are described. Details on dose metrics are provided and a common nomenclature to measure, estimate, and report dose is proposed in order to perform accurate comparisons between publications and practices. Key points of the European and international legislation regarding medical X-ray use are summarized, and radiation protection basics for patients and staff, are detailed. Finally, a literature review is proposed for physicians to evaluate their practice. CONCLUSIONS: Today's trainees will be highly exposed to radiation throughout their practice. It is thus compulsory that they undergo dedicated radiation education during their initial training, and regular refresher sessions later. In daily practice, focus on dose reduction and monitoring of patient and staff exposure are mandatory.

Ethylene vinyl alcohol copolymer (Onyx®) in peripheral interventional radiology: indications, advantages and limitations.

Onyx(®) is a remarkable liquid embolizing agent that may allow a well-trained operator to undertake challenging embolization procedures. In multiple interventional radiology indications, the physico-chemical properties of Onyx(®) allow safe embolization. The purpose of this article is to review the advantages and disadvantages of Onyx(®) and identify its main indications.

Techniques to reduce radiation and contrast volume during EVAR.

There is a large variability observed in the literature regarding radiation exposure and contrast volume injection during endovascular aortic repair (EVAR). Reducing both in order to decrease their respective toxicities must be a priority for the endovascular therapist. Radiation dose reduction requires a strict application of the "as low as reasonably achievable" principles. Firstly, all X-ray system settings should be defaulted to low dose, and fluoroscopic time reduced as much as possible. Digital subtraction angiography runs should be replaced by recorded fluoroscopy runs when possible. Magnification should be avoided, whereas collimation should be systematic to minimize scatter radiation and focus only on the area of interest. Advanced imaging modes can also contribute to dose reduction. For instance, image fusion can facilitate endovascular navigation, and allow table and C-arm positioning without fluoroscopy. In our experience, routine use of image fusion during EVAR significantly reduces both radiation exposure and contrast volumes during complex EVAR. To make these imaging modes useable in real life settings, the X-ray system should be fully controlled by the operator from table side. Reducing iodinated contrast volume, while maintaining image quality, can also be achieved through the use of automated contrast injectors. Additionally, alternative contrast agents, like carbon dioxide (CO2) and gadolinium, have also been evaluated and can be used in specific cases. Contrast-enhanced ultrasound and intravascular ultrasonography are currently developed as potential alternatives to both iodinated contrast use and X-ray during EVAR. Lastly, specific education and training of operators in radiation protection are essential.