Vascular occlusive agents

Absorbable gelatin compressed sponge (Gelfoam) embolization of distal external carotid artery branches in intra-arterial chemotherapy for retinoblastoma

BACKGROUND

In intra-arterial chemotherapy for retinoblastoma, a backflow from unreachable external carotid artery branches in the ophthalmic artery can be challenging.

OBJECTIVE

To describe a new endovascular technique using Gelfoam pledgets to temporarily occlude distal branches of the external carotid artery to reverse the competitive backflow into the ophthalmic artery in order to perform intra-arterial chemotherapy via the ostium of the ophthalmic artery in selected cases.

METHODS

We queried our prospectively collected database of 327 consecutive patients treated for retinoblastoma by intra-arterial chemotherapy and identified those employing Gelfoam pledgets. We describe this new technique with emphasis on feasibility and safety.

RESULTS

We treated 11 eyes with 14 infusions of intra-arterial chemotherapy using Gelfoam pledgets to occlude the distal branches of the external carotid artery. We report no perioperative complications due to this occlusion technique. At the ophthalmologic follow-up 1 month after the injection of Gelfoam pledgets, all cases showed tumor regression or stable disease. Two injections into the same eye as the rescue intra-arterial chemotherapy infusion resulted in a transient exudative retinal detachment, and one injection in a heavily pretreated case was followed by iris neovascularization and retinal ischemia. None of the pledget injections led to irreversible vision-threatening intraocular complications.

CONCLUSIONS

Intra-arterial chemotherapy in retinoblastoma using Gelfoam to transiently occlude the distal branches of the external carotid artery and reverse the backflow into the ophthalmic artery seems feasible and safe. Larges series will help to confirm the effectiveness of this new technique.

Safety evaluation of combination treatment of drug-eluting bead transarterial chemoembolization and immune checkpoint inhibitors for hepatocellular carcinoma: An increased risk of liver abscess with treatment interval less than one month

PURPOSE

To analyze the safety of combination treatment comprising drug-eluting bead transarterial chemoembolization (DEB-TACE) and immune checkpoint inhibitors (ICIs) in hepatocellular carcinoma (HCC).

METHOD

In total, 208 HCC patients receiving DEB-TACE were enrolled for this retrospective single-institution study. Among them, 50 patients who received ICIs at an interval less than one month from DEB-TACE were categorized into the DEB-ICI group; the remaining 158 patients were categorized into the DEB group. Albumin-bilirubin (ALBI) score before and at three months after DEB-TACE were recorded to evaluate liver function changes. Adverse events within three months after DEB-TACE were considered TACE-related and were compared between the two groups.

RESULTS

The DEB-ICI group had significantly higher incidence of liver abscess than the DEB group (14.0 % versus 5.1 %, p-value = 0.0337). No significant difference in the other TACE-related adverse events and change of ALBI score between the groups. Univariate logistic regression confirmed that combination with ICIs was an independent risk factor for liver abscess after DEB-TACE (odds ratio = 3.0523, 95 % confidence interval: 1.0474-8.8947, p-value = 0.0409); other parameters including subjective angiographic chemoembolization endpoint scale and combined targeted therapy were nonsignificant risk factors in this study population. In the DEB-ICI group, patients who received ICIs before DEB-TACE exhibited a trend toward liver abscess formation compared with those who received DEB-TACE before ICIs (23.8 % versus 6.9 %, p-value = 0.0922).

CONCLUSIONS

Combination treatment involving DEB-TACE and ICIs at an interval less than one month increased the risk of liver abscess after DEB-TACE. Greater caution is therefore warranted for HCC patients who receive ICIs and DEB-TACE with this short interval.

Effects of postoperative use of proton pump inhibitors on gastrointestinal bleeding after endoscopic variceal treatment during hospitalization

BACKGROUND

Endoscopic variceal treatment (EVT) is recommended as the mainstay choice for the management of high-risk gastroesophageal varices and acute variceal bleeding in liver cirrhosis. Proton pump inhibitors (PPIs) are widely used for various gastric acid-related diseases. However, the effects of PPIs on the development of post-EVT complications, especially gastrointestinal bleeding (GIB), remain controversial.

AIM

To evaluate the effects of postoperative use of PPIs on post-EVT complications in patients with liver cirrhosis during hospitalization.

METHODS

Patients with a diagnosis of liver cirrhosis who were admitted to the Department of Gastroenterology of the General Hospital of Northern Theater Command, treated by an attending physician between January 2016 and June 2020 and underwent EVT during their hospitalization were included. Logistic regression analyses were performed to explore the effects of postoperative use of PPIs on the development of post-EVT complications during hospitalization. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.

RESULTS

A total of 143 patients were included. The incidence of post-EVT GIB and other post-EVT complications was 4.90% and 46.85%, respectively. In the overall analyses, postoperative use of PPIs did not significantly reduce the risk of post-EVT GIB (OR = 0.525, 95%CI = 0.113-2.438, P = 0.411) or other post-EVT complications (OR = 0.804, 95%CI = 0.413-1.565, P = 0.522). In the subgroup analyses according to the enrollment period, type and route of PPIs after the index EVT, use of PPIs before the index EVT, use of vasoactive drugs after the index EVT, indication of EVT (prophylactic and therapeutic), and presence of portal venous system thrombosis, ascites, and hepatocellular carcinoma, the effects of postoperative use of PPIs on the risk of post-EVT GIB or other post-EVT complications remain not statistically significant.

CONCLUSION

Routine use of PPIs after EVT should not be recommended in patients with liver cirrhosis for the prevention of post-EVT complications during hospitalization.

Fat tissue as an embolic material changes the embolization time in a size-dependent manner: a basic investigation using rabbits

PURPOSE

To evaluate the usefulness of fat tissue as an embolic material and determine whether the embolization time depends on the size of the fat tissue.

MATERIALS AND METHODS

Inguinal fat tissues from 16 rabbits were processed as follows: (1) fat tissues were cut into 2-mm squares, and (2) fat tissue squares were dissociated 20 × through a syringe without a needle (1-139 μm in diameter). The distal main trunk of the right or left renal artery was completely embolized using one of the two types of fat tissue. After 1 or 7 days, renal angiography was performed.

RESULTS

On day 1 after embolization of the renal artery with 2-mm fat tissue squares (Group 1-1) and on day 7 (Group 1-2), the reperfusion rates were 4.0 ± 5.5% and 29.9 ± 6.9%, respectively. On day 1 after embolization of the renal artery with fat tissues dissociated using a 20 × pumping cycle (Group 2-1) and on day 7 (Group 2-2), the reperfusion rates were 59.9 ± 9.9% and 74.3 ± 26.0%, respectively. The reperfusion rates were significantly different between the two types of fat tissue.

CONCLUSIONS

Fat tissue serves as an embolic material that changes the embolization time in a size-dependent manner.

Transarterial embolization of the external carotid artery in the treatment of life-threatening haemorrhage following blunt maxillofacial trauma

Background

Severe bleeding after blunt maxillofacial trauma is a rare but life-threatening event. Non-responders to conventional treatment options with surgically inaccessible bleeding points can be treated by transarterial embolization (TAE) of the external carotid artery (ECA) or its branches. Case series on such embolizations are small; considering the relatively high incidence of maxillofacial trauma, the ECA TAE procedure has been hypothesized either underused or underreported. In addition, the literature on the ECA TAE using novel non-adhesive liquid embolization agents is remarkably scarce.

Patients and methods

PubMed review was performed to identify the ECA TAE literature in the context of blunt maxillofacial trauma. If available, the location of the ECA injury, the location of embolization, the chosen embolization agent, and efficacy and safety of the TAE were noted for each case. Survival prognostic factors were also reviewed. Additionally, we present an illustrative TAE case using a precipitating hydrophobic injectable liquid (PHIL) to safely and effectively control a massive bleeding originating bilaterally in the ECA territories.

Results and conclusions

Based on a review of 205 cases, the efficacy of TAE was 79.4–100%, while the rate of major complications was about 2–4%. Successful TAE haemostasis, Glasgow Coma Scale score ≥ 8 at presentation, injury severity score ≤ 32, shock index ≤ 1.1 before TAE and ≤ 0.8 after TAE were significantly correlated with higher survival rate. PHIL allowed for fast yet punctilious application, thus saving invaluable time in life-threatening situations while simultaneously diminishing the possibility of inadvertent injection into the ECA-internal carotid artery (ICA) anastomoses.

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.

Fabrication of inherently radiopaque BaSO4@BaAlg microspheres by a one-step electrospraying method for embolization

Inherently radiopaque BaSO₄@BaAlg microspheres were fabricated by a one-step electrospraying method for embolization and noninvasive examination after operations.

Endovascular Embolization by Transcatheter Delivery of Particles: Past, Present, and Future

Minimally invasive techniques to occlude flow within blood vessels, initially pioneered in the 1970s with autologous materials and subsequently advanced with increasingly sophisticated engineered biomaterials, are routinely performed for a variety of medical conditions. Contemporary interventional radiologists have at their disposal a wide armamentarium of occlusive agents to treat a range of disease processes through a small incision in the skin. In this review, we provide a historical perspective on endovascular embolization tools, summarize the current state-of-the-art, and highlight burgeoning technologies that promise to advance the field in the near future.

Alteration of Renal Blood Flow during Sequential Embolization of the Canine Kidney

Experimental embolization of the renal artery with cross-linked dextran (CLD) microspheres was performed in 6 dogs. The blood flow was monitored by electromagnetic flow meter (EM) in 3 dogs and by video dilution technique (VDT), adapted to an angiographic digital subtraction system, in a second group of 3 dogs. Retrograde flow in the embolized renal artery was detected by 99Tcm microspheres. Sequential emboli produce a predictable and equal flow response with both measuring techniques. Thus, the less invasive VDT can be used in the clinical setting to optimize and control embolization procedures. This type of flow monitoring has great potential in alerting the angiographer when approaching the risk level for retrograde flow.

Life-Threatening Post-Nephrolithotomy Hemorrhage Resulting in Cessation of Kidney Function, Treated by Transcatheter Arterial Embolization with Subsequent Restoration of Excretory Function

A massive post-nephrolithotomy renal hemorrhage was successfully controlled by selective arterial embolization using Gelfoam particles. Prior to embolization, the kidney showed no excretory function due to complete obstruction of its collecting system by blood clots. Long-term observation revealed restoration of excretory function of the treated kidney and only minimal loss of its parenchyma.

Proton pump inhibitor administration delays rebleeding after endoscopic gastric variceal obturation

AIM: To clarify the efficacy of proton pump inhibitors (PPIs) after endoscopic variceal obturation (EVO) with N-butyl-2-cyanoacrylate.

METHODS: A retrospective study was performed on 16 liver cirrhosis patients with gastric variceal bleeding that received EVO with injections of N-butyl-2-cyanoacrylate at a single center (Kyung Hee University Hospital at Gangdong) from January 2008 to December 2012. Medical records including patient characteristics and endoscopic findings were reviewed. Treatment results, liver function, serum biochemistry and cirrhosis etiology were compared between patients receiving PPIs and those that did not. Furthermore, the rebleeding interval was compared between patients that received PPI treatment after EVO and those who did not.

RESULTS: The patient group included nine males and seven females with a mean age of 61.8 ± 11.7 years. Following the EVO procedure, eight of the 12 patients that received PPIs and three of the four non-PPI patients experienced rebleeding. There were no differences between the groups in serum biochemistry or patient characteristics. The rebleeding rate was not significantly different between the groups, however, patients receiving PPIs had a significantly longer rebleeding interval compared to non-PPI patients (22.2 ± 11.2 mo vs 8.5 ± 5.5 mo; P = 0.008). The duration of PPI use was not related to the rebleeding interval. A total of six patients, who had ulcers at the injection site, exhibited a shorter rebleeding interval (16.8 ± 5.9 mo) than patients without ulcers (19.9 ± 3.2 mo), though this difference was not statistically significant.

CONCLUSION: PPI therapy can extend the rebleeding interval, and should therefore be considered after EVO treatment for gastric varices.

Investigation of acetylated chitosan microspheres as potential chemoembolic agents

The aim was to investigate the potential of chitosan microspheres (CMs) with different acetylation using as a chemoembolic agent. Chitosan microspheres (CMs) were prepared via water-in-oil (W/O) emulsification cross-linking method, and acetylated chitosan microspheres (ACMs) were obtained by acetylation of CMs. Next, we characterized the morphology, size, composition and degrees of deacetylation using scanning electron microscopy (TEM), dynamic laser light scattering (DLS), and Fourier transform infrared spectrometer (FTIR). All microspheres had smooth surfaces and good mechanical flexibility, and all could pass through a 5F catheter. The swelling rate (SR) of CMs decreased significantly with the increase of pH (4.0-10.0) but ACMs did not change under the same conditions. Protein absorption assays suggested that albumin was more greatly adsorbed on CMs than on ACMs. Furthermore, CMs caused more blood clots than ACMs. ACMs caused hemolysis less than CMs (<5% of the time). Data indicated that ACMs had more hemocompatibility. Cytotoxicity tests indicated that ACMs initially had less cell attached proliferation but increased with incubation. In contrast, the relative growth rate of mouse embryo fibroblasts (MEFs) on CMs decreased gradually. The results suggested that ACMs could stimulate the growth of MEFs, and CMs were not cytotoxic to MEFs. Thus, ACMs were more biocompatible with greater potential to be used as chemoembolic material.

Optimal schedule of preoperative embolization for spinal metastasis surgery

STUDY DESIGN

A retrospective study.

OBJECTIVE

To investigate the relationship between intraoperative blood loss during spinal metastasis surgery and the surgical delay after preoperative embolization.

SUMMARY OF BACKGROUND DATA

Delaying surgery after embolization is thought to diminish its effectiveness because of revascularization, but there has been no scientific study that supports this hypothesis.

METHODS

We reviewed data from 66 consecutive posterior palliative decompression surgical procedures for spinal metastasis from thyroid and renal cell carcinoma (39 thyroid and 27 renal) in 58 patients between 2004 and 2012. All patients underwent preoperative angiography. The timing of preoperative embolization was determined on the basis of the operating room and interventional radiologist schedules. Excluding one case who did not receive embolization due to lack of hypervascularity, we analyzed 65 cases to compare intraoperative blood loss according to the completeness of embolization and the time lapse between embolization and surgery.

RESULTS

Surgical procedures were performed on the same day of embolization in 21 cases (same day-group), and on the next day after embolization in 39 cases (next-day group). Five surgical procedures were performed 2 days later. The intraoperative blood loss was significantly lesser with complete embolization than with partial embolization (mean ± standard deviation: 809 ± 835 vs. 1210 ± 904 mL, P = 0.03). Among those with complete embolization, the intraoperative blood loss as well as the perioperative transfusion requirement was significantly lesser in the same-day group than in the next-day group (mean ± standard deviation: blood loss: 433 ± 376 vs. 1012 ± 974 mL, P = 0.01; transfusion requirement: 1.5 ± 1.7 vs. 4.2 ± 4.1 units, P = 0.04).

CONCLUSION

Preoperative embolization showed greater effectiveness in reducing intraoperative blood loss when surgery for spinal metastasis was performed on the same day than when surgery was delayed. Surgery should be performed on the same day of embolization if possible.

LEVEL OF EVIDENCE

4.

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.

Low incidence of complications from endoscopic gastric variceal obturation with butyl cyanoacrylate

BACKGROUND & AIMS

Endoscopic variceal obturation with tissue adhesive is used to control gastric variceal bleeding. We investigated the prevalence of serious complications from this therapy.

METHODS

We performed a retrospective analysis of complications that occurred in 753 patients with gastric variceal hemorrhages who were hospitalized in 2 tertiary referral hospitals. All patients received N-butyl-2-cyanoacrylate as therapy for endoscopic variceal obturation.

RESULTS

Complications occurred in 51 patients. Thirty-three patients experienced rebleeding because of early-onset (within 3 months) extrusion of the N-butyl-2-cyanoacrylate glue cast (4.4%), 10 patients developed sepsis (1.3%), and 5 patients developed distant embolisms (0.7%; 1 pulmonary, 1 brain, and 3 splenic). One patient had major gastric variceal bleeding after endoscopic variceal obturation (0.1%), 1 developed a large gastric ulcer (0.1%), and 1 had mesentery hematoma, hemoperitoneum, and infection in the abdominal cavity (0.1%). The complication-related mortality was 0.53% (3 deaths from sepsis and 1 death from rebleeding after early-onset glue cast extrusion).

CONCLUSIONS

The occurrence of complications after endoscopic variceal obturation with N-butyl-2-cyanoacrylate in gastric varices treatment is rare.

Surgical treatment of sacral chordomas combined with transcatheter arterial embolization

STUDY DESIGN

A retrospective study, analyzing midterm results of transcatheter arterial embolization (TAE) for removal of a sacral chordoma.

OBJECTIVE

To develop a suitable method to maximally remove the tumor.

SUMMARY OF BACKGROUND DATA

Although previous reports have reported the use of TAE for removal of tumors, there is currently no data available on using this method to treat sacral chordomas.

METHODS

Thirty patients with sacral chordomas, who underwent surgical treatment from January 1994 to September 2005, were selected. All 30 patients underwent the posterior approach after TAE of the main arteries that supplied the sacral chordoma. The average follow-up was 44.6 months after the operation. The blood lost during the operation, blood transfusion, and the blood drained from the patient after the operation was reviewed. In addition, the sphincter muscle function of the bladder and bowel was observed.

RESULTS

The intraoperative blood loss averaged 1200 mL during the removal of the tumor. The average blood drained from the patient after the operation was 650 mL. The average blood transfusion postoperatively was 1080 mL. Of the 30 patients, 12 had recurrence and 2 died of tumor metastasis. In the 17 patients whose sacral nerve roots had been bilaterally reserved at and above the S3 level, the sphincter muscle function of the bladder and bowel was good, whereas the function of the sphincter muscles was impaired in 2 patients with nerve roots reserved only at and above the S1 level. In 1 case, colostomy and ureterocutaneosomy were used.

CONCLUSIONS

In comparison with historical literature, preoperative TAE for excising the sacral tumor can significantly decrease intraoperative blood loss, make the surgical field clear, possibly eliminate the need for using an anterior approach, and facilitate the maximal removal of the sacral chordoma. It is an encouraging technique for excising the sacral chordomas.

Use of intra-arterial chemotherapy and embolization before limb salvage surgery for osteosarcoma of the lower extremity

We report our experience with the use of intra-arterial chemotherapy and embolization before limb salvage surgery in patients with osteosarcoma of the lower extremity. We evaluated the effect of this procedure on the degree of tumor necrosis and on the amount of blood loss during surgery. We reviewed the medical records of all patients who received intra-arterial chemotherapy and embolization before undergoing limb salvage surgery for osteosarcoma of the lower extremity at our institution between January 2003 and April 2008. Patient demographic, tumor characteristics, treatment details, postembolization complications, and surgical and pathological findings were recorded for each patient. We evaluated the operative time, estimated blood loss (EBL), and volume of blood transfusion during surgery and in the postoperative period in all patients in the study group. The same parameters were recorded for 65 other patients with lower extremity osteosarcoma who underwent limb salvage operation at our institution without undergoing preoperative intervention. The study included 47 patients (25 males and 22 females). Angiography showed that the tumors were hypervascular. Intra-arterial chemotherapy and embolization were performed successfully, resulting in a substantial reduction or complete disappearance of tumor stain in all patients. No major complications were encountered. At the time of surgery, performed 3-7 days after embolization, a fibrous edematous band around the tumor was observed in 43 of the 47 patients, facilitating surgery. The goal of limb salvage was achieved successfully in all cases. Percentage tumor necrosis induced by treatment ranged from 70.2% to 94.2% (average, 82.9%). EBL during surgery, EBL from drains in the postoperative period, total EBL, and transfusion volumes were significantly lower in the 47 study patients compared to the 65 patients who underwent surgery without preoperative treatment with intra-arterial chemotherapy and embolization. The mean operative time was also significantly less in the intervention group compared to the nonintervention group (73.2 vs. 88.5 min; p < 0.05). In conclusion, intra-arterial chemotherapy and embolization performed 3 to 7 days before limb salvage surgery in patients with lower extremity osteosarcomas can cause substantial tumor necrosis, reduce the EBL and transfusion requirements during surgery, and induce formation of a false capsule around the tumor, thus facilitating surgical excision of the tumors.

Mechanisms of hemostasis at cesarean delivery

Postpartum hemorrhage is an obstetric emergency that represents a major cause of maternal morbidity and mortality. With the recent rise in the cesarean delivery rate, prompt recognition and proper management at the time of cesarean delivery are becoming increasingly important for providers of obstetrics. Preparedness for hemorrhage can be achieved by recognition of prior risk factors and implementation of specific hemorrhage protocols. Medical and surgical therapies are available to treat obstetric hemorrhage after cesarean delivery.

Degradable gelatin microspheres as an embolic agent: an experimental study in a rabbit renal model

Objective

To investigate the basic characteristics of degradable gelatin microspheres (GMSs), including their embolic behavior and degradation periods when they are used as embolic materials in the renal arteries of rabbit models.

Materials and Methods

Based on the GMS particle size, 24 kidneys were divided into 3 groups of eight kidneys, and each group was embolized with a different GMS particle size (group 1:35-100 µm, group 2: 100-200 µm, and group 3: 200-300 µm). From each group, two rabbits were sacrificed immediately after embolization (day 0), and a pair of rabbits from each group underwent an angiogram and were sacrificed on days 3, 7, and 14, respectively, after embolization. The level of arterial occlusion, the pathological changes in the renal parenchyma, and the degradation of the GMSs were evaluated angiographically and histologically.

Results

A follow-up angiogram on days 0, 3, 7, and 14 revealed the presence of wedge-shaped poorly-enhanced areas in the parenchymal phase as seen in all groups. The size of these areas tended to increase with the particle diameter, and persisted up to day 14. On days 3, 7, and 14, parenchymal infarctions were observed histologically in all cases, and this observation corresponded with the parenchyma being supplied by the embolized arteries. GMSs of group 1 mainly reached the interlobular arteries, while those of group 3 mainly reached the interlobar arteries. In all but two cases, the GMSs were identified histologically even on day 14, and sequential degradation was histologically identified in all GMS groups.

Conclusion

GMSs can be used as degradable embolic materials which can control the level of embolization.

Gelatin microspheres: initial clinical experience for the transcatheter arterial embolization

PURPOSE

The purpose of this study is to evaluate the embolization effects of gelatin microspheres (GMSs) when used as an embolic material for transcatheter arterial embolization (TAE) for several organs.

MATERIALS AND METHODS

We prepared GMSs that dissolves in 5 days in extravasuclar tissue. GMSs were used in five cases in total, four cases with multiple liver tumors and one case with a pelvic bone tumor.

RESULTS

In all five cases, it was possible to treat the targeted tumors by TAE with GMSs. In the contrast-enhanced CT performed 2-4 weeks later, the embolized tumors did not show an enhancement effect. Passage of GMSs in the microcatheter was excellent.

CONCLUSION

GMSs showed sufficient potential to be used as an embolic material.

Embolization Materials Made of Gelatin: Comparison Between Gelpart and Gelatin Microspheres

PURPOSE

The object of this study was to assess the level of embolization in the embolized artery and the degradation period of these two embolic agents in the renal arteries using rabbit models.

MATERIALS AND METHODS

The renal artery was embolized using 5 mg of gelatin microspheres (GMSs; diameter, 35-100 mum; group 1) or 1 mg of Gelpart (diameter, 1 mm; group 2). For each group, angiographies were performed on two kidneys immediately after the embolic procedure and on days 3, 7, and 14 after embolization. This was followed by histopathological examinations of the kidneys.

RESULTS

Follow-up angiograms on each day revealed the persistence of poorly enhanced wedge-shaped areas in the parenchymal phase in all cases. In group 1, four of six cases showed poorly enhanced small areas in the follow-up angiograms. In group 2, all cases showed poorly enhanced large areas. In the histopathological specimens, it was observed that immediately after embolization, the particles reached the interlobular arteries in group 1 and the interlobar arteries in group 2. In all cases in group 1, the particles were histologically identified even on day 14. In one case in group 2 on day 14, the particles were not identified.

CONCLUSION

In conclusion, although GMSs and Gelpart were similar in the point of gelatin particles, the level of embolization and the degradation period were different between GMSs and Gelpart.

Nano hemostat solution: immediate hemostasis at the nanoscale

Hemostasis is a major problem in surgical procedures and after major trauma. There are few effective methods to stop bleeding without causing secondary damage. We used a self-assembling peptide that establishes a nanofiber barrier to achieve complete hemostasis immediately when applied directly to a wound in the brain, spinal cord, femoral artery, liver, or skin of mammals. This novel therapy stops bleeding without the use of pressure, cauterization, vasoconstriction, coagulation, or cross-linked adhesives. The self-assembling solution is nontoxic and nonimmunogenic, and the breakdown products are amino acids, which are tissue building blocks that can be used to repair the site of injury. Here we report the first use of nanotechnology to achieve complete hemostasis in less than 15 seconds, which could fundamentally change how much blood is needed during surgery of the future.

Endovascular Therapy for Management of Oral Hemorrhage in Malignant Head and Neck Tumors

PURPOSE

To evaluate the efficacy and safety of endovascular therapy in oral hemorrhage from malignant head and neck tumors.

METHODS

Ten patients (mean age 56 years) with oral hemorrhage caused by malignant head and neck tumors underwent a total of 13 emergency embolization procedures using gelatin sponge particles, steel and/or platinum coils, or a combination of these embolic materials. Angiographic abnormalities, technical success rate, clinical success rate, recurrence rate, complications, hemostatic period, hospital days, survival days, and patient outcome were all analyzed.

RESULTS

Angiographic abnormalities were identified during 85% of procedures (11/13). The technical success rate was 100% (13/13 procedures). The primary and secondary clinical success rates were 77% (10/13 procedures) and 67% (2/3 procedures), respectively. The overall clinical success rate was 92%, and the recurrence rate was 22% (2/9 procedures) in patients whom we were able to observe during the 1-month period after embolization. No major complications occurred. Several patients in whom gelatin sponge particles had been used complained of transient local pain after the procedure. The median hemostatic period was 71 days (range 0-518 days). Median hospital and survival days were 59 days (range 3-209 days) and 141 days (range 4-518 days), respectively. Three patients survived and 7 patients died during the observation period. Only 1 of these 7 patients died from hemorrhage.

CONCLUSION

In conclusion, our findings suggest that endovascular therapy is an effective, safe, and repeatable treatment for oral hemorrhage caused by malignant head and neck tumors.

Superselective embolization of bladder arteries in the treatment of intractable bladder haemorrhage

Bladder hemorrhage following radiation therapy is a serious complication in patients undergoing this treatment. Several methods have been proposed to control this particular situation; however, results have been far from satisfactory, with the exception of drastic measures such as hypogastric artery ligation and radical cystectomy. We recently used a method of superselective embolization of the bladder arteries which enabled us to control severe intractable bleeding in a patient submitted to bladder irradiation for a transitional cell infiltrating carcinoma. Compared to selective embolization and other methods, the advantages of superselective embolization are a lower recurrence rate concerning bleeding, fewer side-effects and the possibility of using adaptable embospheres (150-1000 micron) which, on account of their marked plasticity, offer better occlusion of the vessels. For these reasons, superselective embolization of the bladder arteries should be considered as the treatment of choice in intractable bladder hemorrhage.

Mechanical stress-dependent secretion of interleukin 6 by endothelial cells after portal vein embolization: clinical and experimental studies

BACKGROUND/AIMS

Interleukin-6 (IL-6) is an essential early signal in liver regeneration, however, little is known about what triggers IL-6 release. Changes in portal hemodynamics after portal vein embolization (PVE) may contribute to IL-6 release, leading to regeneration of non-embolized lobe.

METHODS

In 22 patients who underwent right PVE, the diameters of the left portal branches, liver volumes, and serum concentrations of IL-6, tumor necrosis factor-alpha (TNF-alpha), and hepatocyte growth factor (HGF) were measured. We then studied endothelial cells cultured on an elastic silicone membrane and subjected to continuous uni-axial stretch. Supernatant cytokine concentrations were measured.

RESULTS

The diameters of the portal branches increased by 150% after PVE. Serum IL-6 concentrations increased within 3h after PVE. The concentrations of TNF-alpha and HGF remained unchanged. The left lobe volume increased 2 weeks after PVE. The IL-6 concentrations in the supernatant of endothelial cells with stretch stress were higher than that in the non-stretched control group.

CONCLUSIONS

These findings indicate that PVE dilates the portal branches in the non-embolized lobe, exposing hepatic vasculature to stretch stress. This hemodynamic change may act as a trigger for IL-6 release from endothelial cells and contribute to the activation of regenerative cascade in the non-embolized lobes.

A study on the pathogenesis of equine sesamoiditis: the effects of experimental occlusion of the sesamoidean artery

In this study the potential role of circulatory disturbances in the pathogenesis of sesamoiditis was investigated by studying the clinical and histological effects of experimental occlusion of the sesamoidean artery, which is the main nutrient artery of the proximal sesamoid bone (PSB). For this purpose, five adult Dutch Warmblood horses were used in which the sesamoidean artery was occluded with polyvinyl alcohol foam particles. Bone labelling was carried out with oxytetracycline and calcein. All animal were checked clinically three times a week and radiographically at days 14, 21, 28 and 35. At day 35 the animals were killed and the fetlock was dissected and macroscopically evaluated. The PSBs were isolated and radiographed and the soft tissues adjacent to the abaxial side of the PSBs were histologically examined [routine histology and for the neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP)]. The PSBs were divided into bony slices which were radiographed and evaluated histologically (routine, SP, CGRP, fluorescence). All horses showed a slight lameness that gradually diminished. Radiographically enlarged vascular channels were seen in only one horse. Histological data showed that on average 60% (range 37-89%) of the total area had been deprived of vascularization. In two horses an increase in the extent of the arterial network from the basal side of the PSB was seen. Only in the horse with the greatest extent of occlusion were bone necrosis and a reactively increased uptake of fluorochromes adjacent to the occluded arteries found. Bone density did not change. The distribution of neuropeptides in the surrounding soft tissues was not affected by the occlusion. From this study, it can be concluded that a large part of the arterial supply to the PSB can be interrupted without provoking histological and/or radiographic changes that are consistent with clinical sesamoiditis. Therefore, it seems very improbable that circulatory disturbances are a primary aetiopathogenic factor in the disease.

Prevention and treatment of thromboembolic and ischemic complications associated with endovascular procedures: Part I--Pathophysiological and pharmacological features

Thromboembolic and ischemic complications frequently occur during and after endovascular procedures, because of associated arterial injury and the thrombogenic characteristics of arterial catheters, contrast agents, and implanted devices such as coils and stents. Platelet adhesion, activation, and aggregation occurring at the site of arterial injury are mediated by local factors, including thromboxane A2 (inhibited by aspirin) and adenosine diphosphate (inhibited by ticlopidine and clopidogrel). Concomitantly, thrombin is formed by serial activation of clotting factors via contact with subendothelial tissue factor. Thrombin cleaves fibrinogen into fibrin. Thrombin activation is indirectly blocked by heparin and its analogs. However, after thrombin is clot-bound (with fibrin), it is relatively protected from heparin and is effectively blocked only by direct thrombin inhibitors (hirudin and its analogs). The final common pathway in clot formation is the binding of fibrinogen to platelets via platelet glycoprotein IIb/IIIa receptors, which is inhibited by antibodies to platelet IIb/IIIa receptors. New treatment modalities, such as the use of direct thrombin inhibitors and antibodies to platelet glycoprotein IIb/IIIa, seem to be more effective for prophylaxis and treatment than conventional anticoagulation and antiplatelet therapies.

Ruptured hepatocellular carcinoma as a complication of transarterial oily chemoembolization

BACKGROUND

Transarterial oily chemoembolization (TOCE) is frequently employed as a non-operative treatment for hepatocellular carcinoma (HCC). Serious complications of TOCE are well known but ruptured HCC as a fatal complication of TOCE has not been reported previously.

METHODS

A retrospective study was performed on all patients who received TOCE for treatment of HCC from January 1989 to October 1996; the complication of ruptured HCC within 2 weeks from the procedure was recorded.

RESULTS

During the study period, 391 patients received a total of 1443 sessions of TOCE (mean 3.7 sessions per patient) for the treatment of HCC, with an overall median survival of 10.4 months. Six patients developed ruptured tumour within 2 weeks after TOCE, resulting in an overall incidence of 1.5 per cent per patient or 0.4 per cent per procedure. All except one patient died 1-25 days after tumour rupture. Factors common to these six patients included: (1) male sex; (2) large tumour size (range 8-17 cm in diameter); (3) tumour located in the right lobe of the liver; (4) tumour ruptured after the first session of TOCE; and (5) TOCE performed as primary treatment without previous hepatic resection.

CONCLUSION

Ruptured HCC is a serious complication of TOCE although the incidence is low. It occurred predominantly in men after the first session of TOCE for a large irresectable tumour of the right lobe.

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.

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.

Cure, morbidity, and mortality associated with embolization of brain arteriovenous malformations: a review of 1246 patients in 32 series over a 35-year period

Published reports of cure, morbidity, and mortality associated with the embolization of 1246 brain arteriovenous malformations during the last 35 years were reviewed. Embolization resulted in cure in 5% of arteriovenous malformations. The cure rates of embolization were 4% in reports of 708 patients published before 1990 and 5% in reports of 538 patients published since 1990 (P = not significant). Temporary morbidity from embolization was 10%, and permanent morbidity was 8%. Permanent morbidity was 9% before 1990 and 8% since 1990 (P = not significant). Death after embolization of brain arteriovenous malformations occurred in 1% of patients. Mortality associated with the embolization was 2% before 1990 and 1% since 1990 (P = not significant). Long-term morbidity associated with the use of neurotoxic embolization materials is worrisome but has never been proven.

Malignant insulinoma: permanent hepatic artery embolization of liver metastases--preliminary results

PURPOSE

To evaluate permanent hepatic artery embolization of liver metastases of malignant insulinoma as a therapeutic procedure.

METHODS

Three female patients had persistent severe hypoglycemia after distal pancreatectomy because of a malignant insulinoma. Computed tomography (CT) and CT-portography (CTAP) were used for tumor assessment and follow-up and demonstrated multiple hypervascular metastases 0.5-3 cm in diameter in both lobes of the liver. Unilobar sequential transcatheter embolization of the hepatic artery was performed with an interval of 1-2 months between the procedures. Permanent occlusion was achieved by using a mixture of n-butyl-2-cyanoacrylate and ethiodized oil as an embolizing agent.

RESULTS

In all patients, embolization of the hepatic artery was technically feasible and complete occlusion could be obtained. In two patients, collaterals originating from the right inferior phrenic artery were embolized superselectively 3 months after bilobar embolization. CTAP at that time revealed marked decrease in tumor size of more than 50%. All patients responded to the treatment as confirmed by normalization of measurable hormone levels, glucose levels, and disappearance of symptoms. Two patients are still alive after 24 and 31 months from the time of the first embolization. Current investigations revealed normal laboratory data and no further tumor progression in the liver. The third patient died 15 months after the first embolization; she also had developed ileus due to local recurrence of the primary tumor and lymph node metastases.

CONCLUSION

Hepatic arterial embolization appears to be an effective means of palliation for liver metastases of malignant insulinoma. Long-term improvement seems most likely to be the result of extensive ischemia from permanent occlusion.

Preoperative embolization of spinal tumors

PURPOSE

The authors retrospectively reviewed their 6-year clinical experience with preoperative embolization of hypervascular tumors of the spine.

PATIENTS AND METHODS

Fourteen patients ranging in age from 16 to 70 years underwent a total of 17 embolization procedures (one patient underwent four procedures) with polyvinyl alcohol particles. The lesions were located from the lower cervical to upper lumbar spine. The primary symptom at patient presentation was back pain, although several patients had lower extremity weakness. Seven of 14 patients had metastatic lesions from renal cell carcinoma. The remaining seven had a variety of hypervascular lesions.

RESULTS

Embolization was technically successful in all patients. No complications were attributable to the angiography or embolization procedures. Median estimated blood loss during surgical resection was 1.6 L. In one patient, embolization resulted in relief of back pain, allowing surgery to be postponed for 1 month. In two patients, embolization was performed after previous surgery that was unsuccessful due to excessive blood loss. These vertebral lesions were subsequently removed without complication.

CONCLUSIONS

Embolization of vertebral metastases is a safe treatment prior to surgical resection. With appropriate monitoring, complications can be eliminated. The resulting devascularization allows for an aggressive resection of pathologic tissue.

[Experimental studies of embolization of different hepatotropic blood vessels using Bletilla striata in dogs]

Bletilla striata and gelfoam were used as embolizing agents for the embolization of various hepatotropic vessels in dogs. The results proved that Bletilla striata was superior to gelfoam. The mechanisms of embolization by Bletilla striata are attributable to following factors: non--absobent property, mechanical obstruction; effects on coagulative and anticoagulative systems and secondary obstruction resulted from the injury to wall of blood vessels.

N-butyl-2-cyanoacrylate for embolisation of carotid aneurysm

We report the use of an N-butyl-2-cyanoacrylate (NBCA) mixture for embolisation of six cases of carotid aneurysm after detachable balloons, and/or microcoils had been placed in the aneurysm. The mixture was injected into the aneurysm to prevent delayed bleeding or distal migration of the balloons, or microcoils. No subarachnoid haemorrhage or distal migration of the balloons or microcoils occurred up to 4.5 years after embolisation. Reflux of the NBCA mixture into the parent artery occurred in one patient, who had a neurological deficit which recovered in a month. NBCA mixture may be useful in embolisation of intracranial or skull base arterial aneurysms, for reducing the size of remaining lumen in an aneurysm at high risk of rebleeding which accommodate no more balloons or microcoils, or preventing possible delayed migration of balloons or microcoils. However, prevention of leakage of the mixture into the parent artery remains a problem.

Embolization therapy in haemoptysis

Massive haemoptysis is a serious clinical condition to be treated with transcatheter embolotherapy of bronchial and/or other systemic arteries to the lungs. Lung bleeding frequently originates from sites other than bronchials alone. It is important to consider the extensive collateral network between bronchial, intercostal and pulmonary arteries and veins. Between 1980 and 1991, 70 patients were embolized. Fifty individuals were controlled with a mean follow-up time of 62 months. Most frequently pathology was seen in vessels originating from the right upper middle lung region. The embolization agents we used were IBC, NIBC, dura mater particles, and Ivalon+IBC. Recurrent bleeding was noticed in five patients, but not from embolized vessels. No major complications were encountered. Selective embolotherapy with tissue adhesives resulted in good short-term (90%) and long-term (100%) results. In 10% of cases, two or more embolization sessions were needed to cure the patient of haemoptysis.

The pathology of arteriovenous malformations of the brain treated by embolotherapy. II. Results of embolization with multiple agents

Light microscopic and immunohistochemical examination was undertaken of intracranial arteriovenous malformations (AVMs) surgically resected from 18 patients, each of whom had undergone preoperative angiographic embolization with multiple agents. Distinct patterns of tissue reaction to these agents were noted, even when more than one substance was present in a vascular lumen. Avitene produced the mildest tissue response but resulted in relatively early endothelialization and recanalization. Cyanoacrylates were longer-lasting but associated with more acute and chronic (including granulomatous) inflammation and vessel wall changes. Polyvinyl alcohol foam/ethanol mixture had intermediate properties. Endothelial proliferation over embolization material was confirmed using immunohistochemical application of an antibody to cell proliferation-specific proteins. The significance of these findings for combined endovascular and surgical treatment of cerebral vascular malformations is discussed.

Successful excision of a juvenile-type spinal arteriovenous malformation following intraoperative embolization. Case report

The case of a 57-year-old woman with a 14-year history of progressive paraparesis is presented. Selective spinal angiography revealed a juvenile-type spinal arteriovenous malformation (AVM) with a typical large size and rapid flow. The AVM was located primarily in the retromedullary space at the cervicothoracic junction. The AVM was successfully obliterated by intraoperative embolization using isobutyl-2-cyanoacrylate and surgical excision.