Therapeutic embolization with long-term occluding agents and their effects on embolized tissues

Blocked-flow vs. free-flow cyanoacrylate glue embolization: Histological differences in an in vivo rabbit renal artery model

PURPOSE

The purpose of this in vivo animal study was to compare the acute histological effects on the arterial vessel wall of free-flow vs. blocked-flow embolization with metacryloxysulfolane-n‑butyl cyanoacrylate (MS-NBCA) in several concentrations.

MATERIALS AND METHODS

A total of 42 rabbit renal arteries were embolized using MS-NBCA mixed with ethiodized oil. The MS-NBCA concentration was 12.5%, 25%, or 50%. All mixtures were injected under both free-flow and blocked-flow conditions. The rabbits were euthanised 30 min after arterial embolization. Arterial-lumen distension, intimal inflammation and necrosis, peri‑arterial edema, and distality of MS-NBCA penetration were assessed histologically. Multivariable regression analyses were performed using a manual backward procedure, with linear, ordinal and logistic regression to search for factors associated with these outcomes RESULTS: Marked or severe dilatation was observed in 36 out of 42 arteries (86%) and marked or transmural intimal arteritis in all 42 arteries (42/42; 100%). Lumen dilatation caused focal vessel-wall flattening, which resulted in intimal necrosis. Multifocal necrosis extending from the intima to the media occurred in 23 out of 42 kidneys (55%) and peri‑arterial edema with multifocal vascular leakage in 19 out of 42 kidneys (45%). At multivariable analysis, blocked-flow MS-NBCA injection was associated with greater severity of vessel-wall lesions, including intimal arteritis (P = 0.003) and intimal necrosis (P = 0.014), compared to free-flow injection. Blocked-flow injection was also associated with peri‑arterial edema (P = 0.008) and greater distality of MS-NBCA penetration (P = 0.001).

CONCLUSION

Blocked-flow MS-NBCA injection during renal artery embolization is significantly associated with more acute arterial-wall damage and greater distality of glue penetration compared to free-flow injection in a rabbit model. These preliminary findings may have clinical implications, as blocked-flow injection is routinely used to treat specific vascular diseases or malformations in human.

899 serious adverse events including 13 deaths, 7 strokes, 211 thromboembolic events, and 482 immune reactions: The untold story of cyanoacrylate adhesive closure

OBJECTIVE

The aim was to retrieve and analyse the serious adverse events of venous occlusion systems used in cyanoacrylate adhesive closure (CAC) submitted to regulatory agencies.

METHODS

The Total Product Life Cycle (TPLC) database of the US Food and Drug Administration (FDA), the Database of Adverse Event Notifications (DAEN) of the Australian Therapeutic Goods Administration (TGA), and the Yellow Card database of the UK Medicines and Healthcare Products Regulatory Agency (MHRA) were reviewed. Three Freedom of Information (FOI) requests had to be submitted to the MHRA to obtain data.

RESULTS

The TPLC contained 899 reports which included 13 cases of death, 7 strokes, 211 thromboembolic events, and 482 immune reactions. The DAEN recorded three reportable adverse events, and the MHRA recorded seven adverse incidents including one death.

CONCLUSION

CAC is associated with serious adverse events including death. These events are under-reported in the medical literature and only sub-optimally reported to the regulatory agencies.

N-butyl 2-Cyanoacrylate (NBCA) in Nephron Sparing Superselective Embolization of Iatrogenic Renovascular Injuries: A Single Centre Experience

Purpose To evaluate the safety and efficacy of N-butyl-2-cyano-acrylate (NBCA) for endovascular management of iatrogenic renal-vascular injuries and effects on renal function. Material & Methods Fifteen patients with diagnosed or suspected iatrogenic renal vascular injuries, following percutaneous procedures formed the study group. All the patients were having retroperitoneal hemorrhage or hematuria, with hemodynamic instability at the time of presentation. Pseudoaneurysms, active extravasation of contrast, and the arteriovenous fistula were identified as the cause of bleeding on digital subtraction angiography. Patients underwent trans arterial super-selective embolization. Renal function was monitored using serum creatinine, estimated glomerular filtration rate (eGFR), and mean blood pressure of all the patients at immediate post-procedure and two months intervals. Results Technical and clinical success was achieved in all the cases using NBCA alone. Patients improved hemodynamically. None of the patients required repeat embolization. No derangement in renal function was observed immediately after the procedure and at interval follow-up. Conclusion NBCA can be used as a safe embolizing agent to provide a quick and effective cure for iatrogenic renovascular injuries. Renal parenchymal loss can be minimized by super selective technique.

Endovascular Use of Cyanoacrylate-Lipiodol Mixture for Peripheral Embolization: Properties, Techniques, Pitfalls, and Applications

Endovascular embolization agents are particles and fluids that can be released into the bloodstream through a catheter to mechanically and/or biologically occlude a target vessel, either temporarily or permanently. Vascular embolization agents are available as solids, liquids, and suspensions. Although liquid adhesives (glues) have been used as embolic agents for decades, experience with them for peripheral applications is generally limited. Cyanoacrylates are the main liquid adhesives used for endovascular interventions and have a major role in managing vascular abnormalities, bleeding, and many vascular diseases. They can only be injected as a mixture with ethiodized oil, which provides radiopacity and modulates the polymerization rate. This review describes the characteristics, properties, mechanisms of action, modalities of use, and indications of the cyanoacrylate-Lipiodol® combination for peripheral embolization.

Current role of cyanoacrylate glue transcatheter embolization in the treatment of acute nonvariceal gastrointestinal bleeding

INTRODUCTION

Over the past three decades, transcatheter arterial embolization (TAE) has become the first-line therapy for the management of acute nonvariceal gastrointestinal bleeding (NVGIB) that is refractory to endoscopic hemostasis. Advances in catheter-based techniques and newer liquid embolic agents, as well as recognition of the effectiveness of minimally invasive treatment options, have expanded the role of interventional radiology in the treatment of acute NVGIB. Many embolic agents have been used successfully. However, no guidelines exist about the choice of the best embolic agent which is still controversial. Cyanoacrylate glue has gained acceptance over time. This article aims to address the current role of TAE using cyanoacrylate glue for the treatment of acute NVGIB.

AREAS COVERED

The authors undertook a literature review of the current evidence on the use of cyanoacrylate glue in treating patients with acute NVGIB.

EXPERT OPINION

The evidence shows that cyanoacrylate glue is the most clinically useful embolic agent in treating patients with acute NVGIB, despite the need for learning curve, especially in case of coagulopathy. At present, research is ongoing to assess liquid embolic agents in the treatment of patients presenting with acute NVGIB. More research is needed but cyanoacrylate glue show promise for the future.

Advancements in the development on new liquid embolic agents for use in therapeutic embolisation

This review covers the current state-of-the-art in the development of liquid embolics for therapeutic embolisation.

Vascular Anomalies of the Head and Neck Region

Vascular anomalies of the head and neck region are a complex group of lesions that challenge the head and neck physicians. From the very understanding of the difference between its two distinct forms, hemangiomas and vascular malformations to its management remain confusing. The review of this anomaly attempts at comprehensively understanding the disease. Vascular anomalies are easily diagnosed by their clinical presentation, but choice of imaging and management for this spectrum of lesions is varied. The author attempts to categorize the required imaging for the lesion with suggestions on the management of both hemangiomas and vascular malformations. The available treatment options are discussed, and a comprehensive algorithm for management is suggested. Further research in developing drugs that could restrict the growth of these lesions would be the future of the management of vascular lesions.

Safety and effectiveness of transcatheter embolization in the treatment of internal mammary artery injuries

PURPOSE

Demonstrate the role of endovascular management in the treatment of internal mammary artery (IMA) injuries using transcatheter embolization reviewing our 7-year experience.

MATERIALS AND METHODS

Our retrospective analysis of cases consists of a total of 12 patients (8 M and 4 F; mean age 52 years) who underwent angiographic studies and transcatheter embolization for IMA injuries. Causes of vascular injury were divided in high-energy trauma (n = 6), iatrogenic (n = 3) and penetrating injuries (n = 3). Type of trauma, associated injury, imaging findings, treatments and complications were assessed. Imaging findings included active haemorrhage, pseudoaneurysm and focal dissection.

RESULTS

Embolization was performed with microcoils in all patients; complete thrombosis was obtained in four patients by additional injection of Spongostan pledgets and in two patients with 300-500 μm particles. The technical success rate was 100%. No patient died as a direct result of vascular injury; one died of myocardial contusion and one for severe multiorgan failure related to high-energy trauma. No major and minor complications were registered. No patient required emergency surgery or subsequent surgical treatment.

CONCLUSION

Transcatheter embolization offers an effective, efficient and safe alternative to conventional surgical management of IMA injuries.

Embolization of hepatocellular carcinoma with drug-eluting beads: doxorubicin tissue concentration and distribution in patient liver explants

BACKGROUND & AIMS

To follow the local tissue delivery of doxorubicin in HCC explants from patients embolized with drug-eluting beads and to compare it with histologic modifications.

METHODS

Six patients with HCC underwent chemoembolization with doxorubicin-eluting beads (caliber 100-300 μm, dose 75-150 mg) followed by liver transplantation at different time points (8 h to 36 days). On sections of the explanted liver, the tissue concentration of doxorubicin was determined radially around bead-occluded vessels with microspectrofluorimetry. The intra/peritumoral location of the beads and the modifications of the surrounding tissue were determined on an adjacent hematein-eosin-saffron-stained section and compared to drug measurements.

RESULTS

Doxorubicin was detected in the tissue surrounding the beads at all times of explantation. The drug impregnates an area of at least 1.2 mm in diameter around the occluded vessel. The tissue concentration of drug ranges from 5 μM at 8 h to 0.65 μM at 1 month. In patient transplanted at 8 h, no major tissue modification was observed and we found 42% of the beads occluding intratumoral vessels. Drug concentration was not different around intratumoral and peritumoral occluded vessels. After 9-14 days, necrosis was present around 37% of vessels and at 32-36 days, around 40% of vessels. Necrotic tissue was associated with a deeper penetration and a higher concentration of the drug than non necrotized areas, though statistically significant only at 32-36 days.

CONCLUSIONS

Doxorubicin-eluting beads provide a sustained delivery of drug for a period of 1 month and local tissue concentrations above cytotoxic threshold in HCC-bearing livers.

The use of cyanoacrylate adhesives in the management of congenital vascular malformations

This article outlines the use of liquid acrylic adhesives in the management of congenital vascular malformations. Specifically, the chemical features of cyanoacrylates, including the physical and chemical properties, exovascular use of cyanoacrylates, and the techniques for use of these agents, are discussed.

Fatal pulmonary embolism of polyvinyl alcohol particles following therapeutic embolisation of a peripheral arteriovenous malformation

Embolotherapy of arteriovenous malformations (AVM) is not without risk. A 28-year-old woman underwent transcatheter selective embolisation of an AVM in the cheek using polyvinyl alcohol (PVA) microparticles. She became hypoxic and hypotensive post procedure, and had repeated cardiorespiratory arrests despite aggressive support. Resistant hypoxia with gross right heart dilatation on echocardiography suggested extensive pulmonary embolism. She died 24 h later. A postmortem confirmed widespread thrombosis and PVA particles in the pulmonary microvasculature identical to that in the treated AVM. This is the first reported death from PVA particle pulmonary embolism following therapeutic embolisation of a peripheral AVM.

Fertility after bilateral uterine artery embolization in a sheep model

OBJECTIVE

To evaluate the impact of bilateral uterine artery embolization (UAE) upon fertility in sheep.

DESIGN

Prospective study.

SETTING

University-based interventional radiology, pathology, and reproductive physiology units.

ANIMAL(S)

Nineteen control ewes, 10 ewes embolized with polyvinyl alcohol particles (PVA group), and 10 ewes embolized with Tris-acryl gelatin microspheres (TGMS group).

INTERVENTION(S)

Bilateral UAE was performed with 600- to 1,000-mum PVA particles or 700- to 900-mum TGMS particles. Animals of three groups were synchronized and naturally inseminated.

MAIN OUTCOME MEASURE(S)

For each ewe, a hormonal follow-up was performed throughout the gestation. Gestation duration, number and weight of newborns, and fertility and gestation rates were recorded.

RESULT(S)

Mean number of estrus before insemination and gestation duration were not different between groups. There were 47 living newborns: 26 control, 9 PVA, and 12 TGMS. Overall birth weight of newborns was 3.7 +/- 0.9 kg for controls, 3.6 +/- 1.1 kg for TGMS, and 2.2 +/- 0.7 kg for PVA (which was statistically significant vs. control). In the PVA group, there was a statistically significant decrease of fertility rate and gestation rate vs. controls, but this was not the case in the TGMS group.

CONCLUSION(S)

Particles of PVA decrease fertility in sheep and lead to intrauterine growth retardation.

Recanalization and particle exclusion after embolization of uterine arteries in sheep: a long-term study

OBJECTIVE

To compare the long-term evolution of uterine arteries after embolization with the two most commonly used embolic agents for fibroid embolization: nonspherical polyvinyl alcohol (PVA) particles and trisacryl gelatin microspheres (TGMS).

DESIGN

Prospective study.

SETTING

University-based interventional radiology, pathology, and reproductive physiology units.

ANIMAL(S)

Two groups of 10 sheep embolized in the uterine artery.

INTERVENTION(S)

Embolization of the uterine artery with either 600-1000 microm nonspherical polyvinyl alcohol (PVA) particles or with 700-900 microm trisacryl gelatin microspheres (TGMS). Animals were synchronized and naturally inseminated. Animals were killed at 26 months.

MAIN OUTCOME MEASURE(S)

Uteri were examined pathologically for vessel size, site of occlusion, recanalization rate of vessels, and particle location within the vascular wall.

RESULT(S)

The PVA particles were more numerous in the vessels' lumen than the TGMS particles (13.3 +/- 20.8 vs. 2.5 +/- 2.7), were located more proximally than TGMS (97% vs. 68% in the trunk and first branches of the uterine artery), and were found almost exclusively in the intima (99.2%). In contrast, 54.4% of the TGMS particles were found in the intima, and 45.6% partially or totally excluded. The rate of recanalization was not statistically significantly different for PVA and TGMS (65.2% vs. 60.6%).

CONCLUSION(S)

The long-term evolution of uterine arteries was different after uterine artery embolization with PVA and TGMS because PVA particles formed large-sized aggregates that occluded proximal vessels and remained in the vessel intima. Microspheres occluded more distal vessels, and about 50% of them were partially or totally excluded from the vessel.

Use of stent grafts and coils in vessel rupture and perforation

Vessel rupture and perforation are important complications of percutaneous treatment of coronary and peripheral arterial disease. These complications can result in abrupt vessel closure, distal organ injury, bleeding into the surrounding tissue, and death. Prompt management of such complications is therefore critically important. This paper reviews the management of vessel rupture and perforation, including the use of different types of covered stents (balloon-expandable and self-expanding), as well as the various types of embolization coils. Particular focus will be placed on percutaneous coronary artery and peripheral arterial interventions.

Chitin-based Embolic Materials in the Renal Artery of Rabbits: Pathologic Evaluation of an Absorbable Particulate Agent

PURPOSE

To prospectively evaluate the tissue reaction to and the embolic effect and absorption of chitin and chitosan microspheres and polyvinyl alcohol (PVA) in the renal artery of rabbits.

MATERIALS AND METHODS

This experiment was performed in accordance with regulations on animal care and experiments. Thirty-six New Zealand white rabbits were divided into four groups according to the materials (PVA, chitin particles, and chitosan particles, and chitosan microspheres; diameter, 150-250 microm) used for embolization of the right renal artery. A rabbit from each group was sacrificed 1 and 3 days and 1, 2, 4, 8, 16, 24, and 32 weeks after embolization. Gross and microscopic pathologic findings were examined with hematoxylin-eosin, Masson trichrome, and Victoria blue staining.

RESULTS

Gross pathologic findings were examined, and swelling of embolized kidneys was observed 1 and 3 days after embolization, whereas shrinkage of the embolized kidneys was consistently seen after 2 weeks, with a hard consistency and nodular surfaces being noted. At histologic analysis, chitosan microspheres filled the lumen more compactly than did other particles. With PVA, a large amount of capillary formations occurred within the embolized arteries, whereas chitin particles and chitosan microspheres showed a lower rate of capillary formation. The shape of all embolic materials remained intact until week 8, at which time the materials gradually decreased in size and number. The chitosan particles and the chitosan microspheres were absorbed around weeks 16 and 24, respectively.

CONCLUSION

Chitosan microspheres have great potential as a new embolic material since they block blood vessels more compactly with a lower rate of capillary formation. This material is biocompatible, and it is absorbed 24 weeks after embolization.

Estudo comparativo da reação inflamatória renal entre álcool de polivinil - flocular e álcool de polivinil + acetato de polivinil - esférico: estudo experimental

OBJETIVO: Avaliar as características e os efeitos de um agente embólico, disponível comercialmente, consistindo de Polivinil Álcool (PVA) de morfologia flocular, e comparar com um agente esférico, de tecnologia nacional, consistindo de Polivinil Álcool e Polivinil Acetato (PVA + PVAc). MÉTODO: Foram utilizadas fêmeas de coelho albino "New Zealand", submetidas à embolização arterial renal. PVA-flocular foi usado em 24 animais, assim como PVA+PVAc-esférico. Seis animais foram utilizados como controle. Todos foram mantidos em cativeiro até a morte, por períodos pós-operatórios de 48 horas, cinco dias, 10 dias e 30 dias. RESULTADOS: Ambos os agentes promoveram oclusão do vaso e infarto do órgão. O estudo microscópico inicial das artérias embolizadas com PVA-flocular, mostra oclusão com trombo e PVA. Os vasos embolizados com PVA+PVAc-esférico, mostram os agentes ocupando praticamente todo o lúmen. No estudo de 30 dias, observa-se absorção do trombo e retração dos agentes de PVAflocular, criando espaços. E com PVA+PVAc-esférico, pode-se observar os agentes circundados por intensa fibrose. CONCLUSÕES: Ambas as partículas foram efetivas para causar isquemia tecidual. A reação inflamatória foi mais intensa com PVA+PVAc-esférico que também apresentou grau de penetração maior no sistema vascular.

Embolic agents used for bronchial artery embolisation in massive haemoptysis

Massive haemoptysis is a life-threatening disorder that is associated with a high mortality rate. It is mostly caused by bleeding from bronchial circulation. Bronchial artery embolisation is now considered to be the treatment of choice for acute massive haemoptysis. The safety and effectiveness of bronchial artery embolisation for massive haemoptysis has been proved since its first use in 1973. Currently, polyvinyl alcohol (PVA) particles are the most commonly used embolic agent for bronchial artery embolisation worldwide. PVA particles are biocompatible and nonbiodegradable and are considered to be a permanent embolic agent. Gelatin sponge is a temporary embolic agent and can be used as a supplementary agent after initial embolisation with PVA particles. Stainless steel coils are not recommended for embolisation of bronchial artery, although they may be used in the embolisation of internal mammary artery to preserve the normal vascular territory. Recently, the interest in the use of new embolic agents for bronchial artery embolisation is emerging because of inherent limitations of PVA particles as an intravascular embolic agent. Tris-acryl gelatin microspheres are a new embolic agent that is increasingly used for uterine fibroid embolisation. Tris-acryl gelatin microspheres have characteristics that make it an attractive alternative to PVA particles for bronchial artery embolisation. Clinical trials and experimental studies should be performed to explore the safety and efficacy of microspheres for bronchial artery embolisation.

Location of Vessel Occlusion of Calibrated Tris-acryl Gelatin Microspheres for Tumor and Arteriovenous Malformation Embolization

PURPOSE

To evaluate (i). the presence and number of calibrated tris-acryl gelatin microspheres (TGMS) in targeted organs after embolization of tumors or arteriovenous malformations (AVMs) and (ii). the possible correlations among the size of TGMS used for embolization, the size of TGMS found in specimens, and the size of the occluded vessels.

MATERIALS AND METHODS

Histologic slides were reviewed of 92 specimens from 80 patients with primarily head and neck tumors or AVMs operatively treated after embolization with TGMS of various sizes (40-120 microm, 100-300 microm, 300-500 microm, 500-700 microm, 700-900 microm, and 900-1200 microm). The diameters of the vessels containing TGMS, the size of TGMS, and the thickness of the inflammatory reactions developed around them were measured, and the location of the microspheres was recorded.

RESULTS

TGMS were found in 88% of the specimens; 1985 embolized vessels containing TGMS were analyzed. The median number of TGMS per vessel was one (mean +/- SD, 3.1 +/- 6.9). The diameter of the occluded vessels increased significantly (P <.0001) with increased size of TGMS used for embolization. In tumors, 92% of the occluded vessels were located inside the tumor.

CONCLUSION

There is an obvious correspondence between the size of the TGMS used for embolization and the diameter of the occluded vessels. This correlation confirms the possibility that the vessels to be occluded can be precisely targeted with the use of a proper TGMS size range.

Techniques and applications of transcatheter embolization procedures in pediatric cardiology

Transcatheter embolization of congenital or acquired superfluous vascular structure has become routine procedures performed by interventional pediatric cardiologists. Embolization procedure is often part of a collaborative effort with cardiac surgeons to palliate complex congenital heart defect, such as in embolizing aortopulmonary collateral arteries in patient with single ventricle physiology. In other cases, the procedure is the definitive treatment as in embolizing coronary artery fistula. Pediatric cardiologists performing embolization procedures should be familiar with available technologies as well as understand the underlying cardiac anatomy and pathophysiology. This article provides a comprehensive review of presently available embolization agents and technologies. Some of the technologies are used only by interventional radiologists but may be useful to pediatric cardiologists. Specific clinical applications in pediatric cardiology are also discussed with summary of current literature. With continue advancement in transcatheter technology and operator expertise, all unwanted vascular communication should be amenable to transcatheter embolization.

Efficacy and morbidity of therapeutic renal embolization in the spectrum of urologic disease

PURPOSE

We report the largest series of renal embolizations performed for a variety of indications.

PATIENTS AND METHODS

A retrospective analysis was performed on embolizations performed in our institution from 1997 to 2002 encompassing 36 patients who underwent 44 procedures.

RESULTS

Embolization was successful on the first attempt in 87% of the patients. A second embolization was performed in four of the five unsuccessful cases, three successfully, increasing the success rate to 95%. The mean postoperative narcotic use was 27.2 mg of morphine equivalent, and 10 mg or less was required by 45% of the patients. In the 14 patients who had not also undergone a surgical procedure, the mean narcotic use was 21 mg, and 64% required 10 mg or less. Only 15% of the patients developed fever, which resolved within 2 days in all cases. Leukocytosis was seen in 47%. Follow-up creatinine and hypertension information was available in 16 and 18 patients, respectively. After a mean follow-up of 269 days, only one patient had a clinically significant rise in the creatinine concentration. After a mean follow-up of 496 days, two patients had new-onset hypertension. There was no statistically significant difference in the success rate, narcotic use, complications, creatinine concentrations, or the likelihood of fever, leukocytosis, or hypertension according to the indication for embolization or the agent used. Use of a microcatheter was associated with less parenchymal loss, and decreased parenchymal loss was associated with a significant reduction of narcotic use.

CONCLUSIONS

Renal embolization is a highly effective and well-tolerated procedure in a variety of urologic conditions. The indications and material used did not have a significant effect on the outcome. Reducing parenchymal loss can significantly reduce morbidity.

Emergency endovascular embolization of traumatic intrarenal arterial pseudoaneurysms with N-butyl cyanoacrylate

AIM

The aim of this study is to report the effectiveness of selective endovascular embolization with N-butyl cyanoacrylate (NBCA) in the treatment of traumatic intrarenal arterial pseudoaneurysms.

MATERIALS AND METHODS

Five patients (four males and one female) presented with massive haematuria. Five pseudoaneurysms were detected angiographically, and in all of the cases the aetiology was penetrating trauma. The pseudoaneurysms ranged in size between 7 and 30 mm (mean: 13.8 mm). After the superselective catheterization with a microcatheter-microguidewire system, embolization was performed using NBCA and Lipiodol mixture.

RESULTS

All the pseudoaneurysms were successfully embolized and excluded from the circulation without any other major intrarenal arterial branch occlusion. There were no major or minor complications related to the embolization procedures. Haematuria ceased in 1-3 days after the embolization, and during the follow-up period both re-bleeding and deterioration of renal function did not occur.

CONCLUSION

The endovascular management of renal artery branch pseudoaneurysms by embolization with NBCA is a reasonable and an effective therapeutic technique.

Pathologic features of uteri and leiomyomas following uterine artery embolization for leiomyomas

The objectives of this study were to identify the presence/absence and location of any embolic material and to describe the morphologic appearance of the leiomyoma and adjacent tissues of cases undergoing surgical intervention following uterine artery embolization (UAE) for leiomyomas. A total of 555 women underwent UAE using polyvinyl alcohol particles (PVA) in a multicenter clinical trial. The histopathologic slides from 17 of 18 women who subsequently underwent myomectomy or hysterectomy in the follow-up period (median 8.2 months) were reviewed without knowledge of the indication for surgery or time elapsed since UAE. The presence/absence and distribution of PVA emboli, associated inflammatory response, and necrosis were noted. Necrosis of leiomyoma(s) was classified as hyaline-type, coagulative tumor cell necrosis, and/or acute suppurative necrosis. In all cases PVA emboli were identified within smooth muscle tumors of the uterine body, its periphery, cervix, uterine body, myometrium, and/or the adnexa. A florid foreign body giant cell type of chronic inflammatory reaction was seen within 1 week of UAE and persisted with visible PVA for up to 14 months post-UAE. Typically, post-UAE leiomyomas showed hyaline-type, but rarely coagulative tumor cell necrosis and acute suppurative necrosis could be seen as well. Five of eight cases coming to surgery for complications showed necrotizing endomyometritis with tissue infarction. PVA particles are recognizable in post-UAE specimens. Leiomyoma necrosis is typically of the hyaline type; coagulative tumor cell necrosis was rarely seen. In some cases with complications, uterine and/or cervical necrosis occurred. The applicability of these findings for UAE patients who have been successfully treated and not resected is uncertain.

Pathologic evaluation of a spherical polyvinyl alcohol embolic agent in a porcine renal model

PURPOSE

To evaluate the effects of a spherical embolic agent consisting of polyvinyl alcohol (PVA) and to compare this agent with commercially available embolization agents.

MATERIALS AND METHODS

Eleven miniature pigs were included in the study population. The upper poles of both kidneys were selected as the target organs for embolization. PVA spheres (700-900 micro m) were used in nine kidneys, PVA particles (500-710 micro m) were used in six kidneys, gelatin spheres (700-900 micro m) were used in five kidneys, and gold-colored gelatin spheres (700-900 micro m) were used in three kidneys. Two animals were killed immediately after embolization. In the remaining animals, angiography was performed before sacrifice 7 days (in five pigs) or 28 days (in four pigs) after embolization. Pathologic and histologic evaluation of the kidneys was performed.

RESULTS

All agents resulted in target vessel occlusion and end-organ infarction. All arteries embolized with spherical agents were recanalized at follow-up angiography. In vessels embolized with PVA particles, the occluding plug consisted of thrombus and PVA. In vessels embolized with spherical agents, the occluding plug consisted mostly of the embolic agent. PVA spheres were associated with the mildest inflammatory responses at 7 and 28 days when compared with PVA particles and gelatin-based microspheres. Arterial wall destruction was seen to a greater extent in kidneys embolized with gelatin-based microspheres than in those embolized with PVA-based agents.

CONCLUSIONS

The spherical, PVA-based embolization agent resulted in target organ infarction and temporary arterial occlusion. The inflammatory response to PVA spheres was significantly less aggressive than the response to other agents tested. Further study with clinical and long-term pathologic follow-up is suggested to determine if these findings may have favorable clinical implications for patients undergoing embolization procedures.

Tissue response to N-butyl-2-cyanoacrylate after percutaneous injection into cutaneous vascular lesions

Despite the fact that cyanoacrylates, a group of rapidly polymerizing adhesives, are used widely in general surgery, neuroradiology, otolaryngology, and plastic surgery, scientific data on histopathological changes resulting from the deposition of -butyl-2-cyanoacrylate (NBCA), a new-generation cyanoacrylate derivative, in human tissues is based largely on experimental observations in animals and sporadic postmortem studies in humans. The authors report the consecutive pathological findings of a patient who underwent surgery for facial hemangioma after percutaneous injection of NBCA for devascularization of a lesion, and underwent additional surgery 1 and 6 months after the initial operation for the removal of the residual NBCA cast from the injection site. Acute inflammatory findings after injection of NBCA and the development of a chronic granulomatous foreign body reaction support the histological findings of experimental animal studies and postmortem examinations on humans. Additionally, their findings support the proposed hypothetical sequence of events for the recanalization of cyanoacrylate-embolized vascular structures.

Preoperative silk suture embolization of cerebral and dural arteriovenous malformations

OBJECT

The aim of this study was to evaluate the use of silk sutures as a medical implant when applied for the embolization of cerebral and dural arteriovenous malformations (AVMs). The facility of surgery and the clinical significance of complications related to preoperative silk suture embolization were evaluated immediately after surgery and at long-term follow up.

METHODS

Thirty-four patients harboring 29 cerebral and five dural AVMs underwent embolization in which silk alone or in association with other agents was used. Medical and radiological records obtained in these 34 patients were reviewed retrospectively. The cerebral AVMs were classified according to the Spetzler-Martin grading system and the dural AVMs to the Djindjian grading system. The facility of the resection and the adverse outcomes, including new neurological deficits, hemorrhage, and fever, as well as histopathological evidence of vessel inflammatory changes, were determined in each case. In all 23 surgical cases, the AVM could be easily manipulated and excised. New temporary neurological deficits occurred in three patients. A high Spetzler-Martin grade was not associated with a higher incidence of new neurological deficits. One delayed-onset hemorrhage was detected after embolization. Fever was present in 24% of the patients. No sign of significant vasculitis or perivascular inflammation was found on radiological or histopathological examination.

CONCLUSIONS

Silk sutures are safe embolic agents especially for proximal occlusion of AVM feeding vessels. New permanent neurological deficits were not encountered in this series. Fever was considered to be a minor, temporary side effect of silk suture embolization.

The use of cyanoacrylate adhesives in peripheral embolization

Although liquid adhesives or glue have been used as embolic agents for nearly three decades, experience with them outside of neurointerventional indications is generally limited. Cyanoacrylates are the main liquid adhesives used in the vascular system and have an important role in managing vascular abnormalities, especially arteriovenous malformations. Vascular occlusion results as these agents polymerize on exposure to the ions in blood. A description of the properties, biologic interactions, techniques of use, and indications for acrylic embolization in the peripheral circulation is especially pertinent at this time because of the recent approval of n-butyl cyanoacrylate by the United States Food and Drug Administration.

Displacement of coils into the lung during embolotherapy: clinical importance and follow-up with helical CT

RATIONALE AND OBJECTIVES

The authors performed this study to evaluate the clinical importance and computed tomographic (CT) appearance of coils displaced into the lung during embolotherapy.

MATERIALS AND METHODS

The authors retrospectively studied clinical charts and serial chest images from 25 consecutive patients after coil embolization. Chest radiography was performed in all patients, whereas helical chest CT was performed only in patients in whom dislocated coils were visible on chest radiographs. Coils were applied for the treatment of peripheral arteriovenous (AV) malformations and fistulas (n = 9), renal AV malformations or fistulas (n = 8), and primary or secondary tumors (n = 8). Clinical charts were analyzed for short- and long-term symptoms; chest radiographs and CT scans were reviewed for signs indicative of pulmonary infarction.

RESULTS

None of the patients had clinical symptoms suggestive of pulmonary infarction. In two of the 25 patients (8%), displaced coils were seen in the pulmonary vasculature at chest radiography; these patients had been treated for renal AV fistula and peripheral AV fistula, respectively. One patient had two coils in the left hemithorax (upper and lower lobe), and the other patient had two coils in the right hemithorax (middle lobe). Neither of the patients had abnormalities suggestive of pulmonary infarction at helical CT.

CONCLUSION

Chest radiography can help confirm the presence of coils displaced to the pulmonary vasculature during embolotherapy. Helical CT can also help rule out the presence of coil-associated pulmonary infarction.

Value of bronchial artery embolisation with platinum coils in tumorous pulmonary bleeding

We performed bronchial artery embolizations (BAE) using platinum coils with Dacron fibres in 30 consecutive patients with haemoptysis due to bronchial carcinoma. The aim of the study was to compare immediate results of bleeding cessation, recurrence and survival rates with a historical control group of 15 patients with tumorous pulmonary bleeding who were treated conservatively (non-BAE-group). Bronchial artery embolisation with platinum coils stopped active bleeding in all patients immediately. Comparing the BAE group and controls the cessation of first time haemoptysis (BAE 100% versus non-BAE 93%) and the rates of bleeding recurrence (BAE 50% versus non-BAE 47%) were similar in either group. In case of recurrent bleeding, repeated BAE led to a definite cessation of pulmonary haemorrhage in every case. In contrast, all patients with recurrent haemoptysis without a repeated BAE (8 patients, 27%) and all patients with bleeding recurrence in the non-BAE group died from pulmonary haemorrhage (8 patients, 53%). The mean survival time of the BAE group was significantly longer compared with the non-BAE group, 139 (range: 1-818) days versus 62 (range: 1-186) days (P<0.05). We conclude that consistent BAE proved beneficial in tumorous pulmonary bleeding, particularly with regard to the permanent arrest of haemorrhage in case of recurrence.

Comparison of preoperative embolization followed by radical nephrectomy with radical nephrectomy alone for renal cell carcinoma

A series of 474 patients with renal cell carcinoma (RCC), who had radical nephrectomy during a period of 15 years, was studied to assess the prognostic significance of various pathologic parameters (tumor stage [pT], lymph node status, metastasis, tumor grade, venous involvement) and value of preoperative embolization of renal artery. There were: 20 (4%) pT1, 204 (43%) pT2, 245 (52%) pT3, and 5 (1%) pT4 patients. All 474 patients underwent nephrectomy including a group of 118 (25%) patients (24 pT2, 90 pT3, and 4 pT4) who underwent preoperative embolization of the renal artery. To compare treatment outcomes in embolized patients with RCC, a group of 116 (24%) nonembolized patients with RCC was selected. This group was matched for sex, age, stage, tumor size, and tumor grade, with the embolized patients (p<0.01). All important prognostic factors were studied as to their influence on survival by the treatment group. The overall 5- and 10-year survival was 62% and 47%, respectively. The 5- and 10-year survival rates were significantly better (p<0.01) for patients with pT2 than for those with pT3 tumors (79% vs. 50% and 59% vs. 35%, respectively). Involvement of regional lymph nodes (N+) was an important prognostic factor for survival in patients with pT3 tumors. The 5-year survival for pT3 N+ was 39%, compared with 66% in those with pT3N0 (p<0.01). Preoperative embolization was also an important factor influencing survival. The overall 5- and 10-year survival for 118 patients embolized before nephrectomy was 62% and 47%, respectively, and it was 35% and 23%, respectively, for the matched group of 116 patients treated with surgery alone (p = 0.01). The most important finding of this study was an apparent importance of preoperative embolization in improving patients' survival. This finding needs to be interpreted with caution and confirmed in a prospective randomized trial.

Transcatheter arterial embolization of ruptured pseudoaneurysms with coils and n-butyl cyanoacrylate

PURPOSE

To evaluate the clinical efficacy of transcatheter arterial embolization with n-butyl cyanoacrylate (NBCA) for ruptured pseudoaneurysms, which are difficult to control by coil embolization alone.

MATERIALS AND METHODS

Ruptured pseudoaneurysms developed at the celiac trunk (n = 1), gastroduodenal artery (n = 2), pancreatic arcade (n = 1), hepatic artery (n = 3), renal artery (n = 1), and intercostal artery (n = 1) in nine patients. NBCA was mixed with iodized-oil (1:2) and injected via the 3-F microcatheter under fluoroscopic guidance, after the catheter was advanced close to the pseudoaneurysm. Coil embolization was performed to control blood flow before administration of NBCA in seven patients. NBCA was injected immediately after coil embolization in four patients. Embolization with NBCA was performed for recurrent bleeding that occurred within 1-21 days (mean, 10.7 days) after initial coil embolization in three patients. Two patients with peripheral pseudoaneurysms underwent embolization with NBCA alone.

RESULTS

The NBCA mixture was visible under fluoroscopy, and was useful in monitoring the embolization process and deciding the endpoint. Embolization was technically successful without major complications in all patients. Pseudoaneurysms and afferent and efferent arteries were eliminated immediately after embolization. Bleeding was stopped after embolization in all cases. Rebleeding did not occur in any patient during their follow-up periods of 0.7-69.5 months (mean, 17.9 months).

CONCLUSION

Embolization with NBCA is a feasible and useful treatment for ruptured pseudoaneurysms, which are difficult to control by coil embolization alone.

Materials and biomaterials for interventional radiology

Devices used in interventional radiology have significantly developed in the past few years. In order to understand the trends of this development, we analyzed how new interventional devices are progressively incorporating materials having original physical properties, and how developers are today progressively turning towards biomaterials, with respect to the new regulatory environment, and the requirements of biocompatibility.

Bone metastases from renal cell carcinoma: preoperative embolization

PURPOSE

To assess the effect of preoperative embolization on blood loss during surgical repair of bone metastases from renal cell carcinoma and provide long-term follow-up.

PATIENTS AND METHODS

Sixteen patients with bone metastases underwent preoperative embolization. Polyvinyl alcohol (PVA) particles were used for 13 patients (three with additional coils), and coils alone were used in three patients. Surgery was performed within 24 hours in four patients, and within 36-120 hours in 12 patients. Bone healing was evaluated radiographically and clinically.

RESULTS

Tumor stain was obliterated by more than 70% in 12 patients, 51%-69% in two patients, and less than 50% in two patients. Estimated blood loss (EBL) during surgery ranged from 100 to 1,000 mL (mean, 533 mL). EBL was significantly less when more than 70% of the tumor stain was obliterated (460 mL vs 750 mL; P < .01 ). There were no significant differences in EBL between the patients who underwent surgery within 24 hours (575 mL) and those who underwent surgery more than 36 hours after embolization (402 mL) when PVA was used. Bone healing was achieved in all patients. Survival ranged from 3 to 56 months (median, 12 months).

CONCLUSION

Preoperative embolization reduced intraoperative blood loss without adverse effects on healing. Best results were achieved when more than 70% of the tumor stain was obliterated.

The factors related to recurrence after transcatheter arterial embolization for the treatment of hemoptysis

OBJECTIVES

Massive hemoptysis is a major clinical problem associated with high morbidity and mortality. Transcatheter arterial embolization is widely used for the treatment of massive hemoptysis, but it was reported that the recurrence rate after embolization is 12-54% in the previous studies. We evaluated the therapeutic effect of transcatheter arterial embolization for the treatment of massive hemoptysis and the factors related to recurrence.

METHODS

We reviewed 51 patients (M:F = 36:15) of transcatheter arterial embolization for the treatment of massive hemoptysis from Jan 1988 to Dec 1994, retrospectively.

RESULTS

After arterial embolization, immediate successful control (< 1 wk) of massive hempotysis was achieved in 48 of 51 patients (94.1%) and recurrence of hemoptysis was observed in 17 of 51 patients (33.3%) during the follow-up period. The patients with non-bronchial artery hemoptysis and multiple artery bleeding had increased tendency of recurrence (77.7%). On the previous history of hemoptysis, the patients with massive hemoptysis (> 400 ml/24hr) or frequent history of hemoptysis had increased tendency of recurrence (87.5%, 72.7%).

CONCLUSION

Transcatheter arterial embolization is a useful and safe procedure for immediate control in massive hemoptysis. However, the patients with this procedure had a potentiality for recurrence. We suggest that close follow-up and caution will be needed in the patients with multiple artery bleeding or with large amounts of hemoptysis or with previous episodes more than 3 times.

Embolic materials for endovascular treatment of cerebral lesions

Recently developed soft microcatheters can be maneuvered endovascularly into the brain, permitting treatment of lesions without conventional neurosurgery. Progress in biomaterial science has contributed significantly to the development of this new therapeutic modality termed intravascular neurosurgery or interventional neuroradiology. Although embolic materials play an important role, ideal materials have yet to be devised. Various embolic materials in clinical use are reviewed, such as cyanoacrylates, ethylene-vinyl alcohol copolymer mixtures, Ethibloc, ethanol, estrogen, poly(vinyl acetate), cellulose acetate polymer, poly(vinyl alcohol), gelatin sponges, microfibrillar collagen, surgical silk sutures, detachable balloons, and coils. The materials are reviewed in the context of treatment application for various brain lesions, such as arteriovenous malformations, cerebral aneurysms, and head and neck tumors. Further developments in biomaterial polymer science can bring about progress against brain diseases.

Embolization therapy in pediatric cardiology

Transcatheter embolization therapy has assumed an important role in the management of patients with congenital heart disease. A variety of embolization materials, most commonly steel coils, is available to treat or palliate patients with aortopulmonary collateral vessels or surgical shunts, arteriovenous malformations, and anomalous venovenous connections (common after surgical intervention for the univentricular heart). At many centers, coil occlusion has recently become the treatment of choice for patients with a restrictive patent ductus arteriosus (PDA). This article describes the materials and techniques of embolization therapy, as well as the common indications encountered in the practice of pediatric interventional cardiology.

Intravascular treatment of spinal arteriovenous malformations using a microcatheter--with special reference to serial xylocaine tests and intravascular pressure monitoring

Spinal arteriovenous malformations (spinal AVMs) are now treated using microcatheters and various embolic materials. Interventional techniques of this type are thought to be the first choice for treatment of spinal AVMs. In this study, we used the Tracker vascular access system and MAGIC catheter for intravascular treatment of spinal AVMs in order to avoid proximal occlusion. Notably, serial provocation tests using xylocaine (20 mg in bolus) and intermittent intravascular pressure monitoring in the anterior spinal artery were conducted during embolizations of five intramedullary AVMs. We used 150-350 microns polyvinyl alcohol particles (Ivalon) and/or polyvinyl alcohol (PVA) solutions as embolic materials for occlusion of these AVMs. Vital signs and neurologic functions were carefully monitored during and after the procedure. We were able totally to obliterate the nidus or markedly to reduce its size while preserving the anterior spinal artery in each of the patients. The xylocaine test was conducted an average of 2.6 times (2-4 times) during embolization. For the two patients who were treated with Ivalon and PVA solutions, the final provocation test became positive, and the embolization procedure was terminated. On the other hand, the remaining patients had a positive result on first xylocaine test and were treated with Ivalon alone. At the same time, intravascular pressure monitoring was performed via the microcatheter, which was located in the anterior spinal artery. The value of the intravascular systolic pressure prior to embolization was 71.6 +/- 14.1 mm Hg and it gradually increased during the procedure, and reached 99.6 +/- 12.6 mm Hg (90% of the systemic systolic blood pressure) by the conclusion of embolization. Serial xylocaine tests and intravascular pressure monitoring may be useful for the treatment of spinal AVMs fed mainly by the anterior spinal artery, and embolization with liquid embolic material should be terminated when the provocation test becomes positive and intravascular pressure increased to 90% of the systemic blood pressure.

Arteriovenous malformations of the brain: choosing embolic materials to enhance safety and ease of excision

The authors report their experience with surgical resection of 108 previously embolized arteriovenous malformations (AVM's). Embolization was performed via only transfemoral catheterization in 70 lesions and via the surgical exposure of feeding vessels in 32. The remaining six patients were referred for resection following silicone sphere embolization elsewhere. Materials used included polyvinyl alcohol (PVA) foam, platinum microcoils, detachable silicone balloons, surgical silk, a mixture of 33% ethanol and microfibrillar collagen, and isobutyl cyanoacrylate (IBCA). It is believed that proximal arterial occlusion with balloons is an inferior choice for preresection embolization, because the technical difficulty of placement is high and the nidus of the AVM is unaffected. Vascular coagulation and section and AVM retraction are more difficult with IBCA; therefore, this is also considered an inferior choice. Among the materials studied, the combination of PVA for distal occlusion and microcoils for proximal occlusion appears to be the superior choice. Fewer complications (stroke or hemorrhage) are seen when intraarterial Amytal (amobarbital) testing is used to guide the embolization. Data regarding toxicity, oncogenicity, and vascular metabolism or recanalization associated with PVA, IBCA, and n-butyl cyanoacrylate are reviewed.

Superselective embolization of spinal arteriovenous malformations using the Tracker catheter

Eighteen patients with spinal arteriovenous malformations had been treated with conventional embolization, surgical removal, feeder ligation, and/or feeder coagulation between February 1985 and March 1990. The lesions included six glomus, four juvenile, three extramedullary, and five dural arteriovenous malformations or fistulas. Embolic therapy was conducted in 14 patients by introducing the tip of a catheter into the segmental arteries and injecting polyvinyl alcohol strips (500-1000 microns) (conventional embolization). Follow-up spinal angiography disclosed recanalization in 10 patients (71.4%) and the appearance of new feeding arteries in five patients (35.7%). We introduced the Tracker vascular access system in April 1990. Eight patients (four glomus, one juvenile, and three dural arteriovenous malformations) were treated with the minicatheter and Ivalon particles (150-350 microns). Five patients showed neurological improvement immediately after treatment. The other three patients had severe paraparesis before treatment and did not show any improvement. One patient with a glomus-type arteriovenous malformation showed transient neurological deterioration just after embolization with the Tracker-10 to occlude a lesion fed by the posterior spinal artery, because the Ivalon particles migrated into the anterior spinal artery via the anterior spinal canal artery. In one patient with a juvenile arteriovenous malformation, the Tracker-18 catheter perforated the radiculomedullary artery originating from the right vertebral artery, and subarachnoid hemorrhage occurred. However, the Tracker-10 could later successfully occlude the arteriovenous malformation. The rates of recanalization and appearance of the new feeding vessels were 4/8 (50.0%) and 2/8 (25%), respectively.

Histopathological follow-up study of 66 cerebral arteriovenous malformations after therapeutic embolization with polyvinyl alcohol

Embolization with polyvinyl alcohol (PVA) is an accepted method of rendering complex arteriovenous malformations (AVM's) more amenable to surgery, but its effects on human vascular tissues have not been adequately documented. The authors reviewed the histopathology of 66 intracranial AVM's resected 1 to 76 days after embolization with PVA. The mean age of the patients was 36 years, and their AVM's were located in the cerebral hemispheres (92%), the cerebellum (6%), or the corpus callosum (2%). In 79% of cases, at least one vessel contained PVA particles; in most cases, the vessel was filled with sharp, angular PVA particles in a serpiginous pattern. Polyvinyl alcohol particles indented the endothelium in 69% of cases but were rarely found subendothelially. Clotted blood and fibroblasts were present among the particles, and abundant intraluminal mononuclear and polymorphonuclear inflammatory cells were found in all vessels containing PVA particles. Foreign-body giant cells appeared 2 to 14 days after embolization in the majority of cases. Patchy mural angionecrosis and necrotizing vasculitis were found in 39% of the cases. Recanalized lumina were seen in 18% of PVA-embolized vessels. Foreign materials resembling cotton fibers and other particulate substances, which were probably contaminants of the contrast solution or the embolic material, were found in 65% of the cases. These findings suggest a specific chain of events in the interaction between PVA and vessel wall components and may explain some important sequelae of embolization therapy.