Polymerization kinetics of n-butyl cyanoacrylate glues used for vascular embolization

Optimal combination of microcoils, flow control, and n-butyl cyanoacrylate-Lipiodol-iopamidol (2:3:1) for feasible embolization of medium-sized arteries in an in vitro vascular model

PURPOSE

To evaluate the behavior of n-butyl cyanoacrylate-Lipiodol-iopamidol at a ratio of 2:3:1 (NLI231) with and without microcoils and/or flow control in embolization of medium-sized arteries in an in vitro vascular model.

MATERIALS AND METHODS

A vessel model representing a common hepatic artery was prepared. Six scenarios were set for embolization, each ran three times: 1) NLI231 injected alone with flow control to 0 ml/min during and up to 5 min after embolization; 2) NLI231 injected into a mesh of microcoil of 5% density with the flow control; 3) NLI231 injected into a microcoil of 10% density with the flow control; 4) NLI231 injected alone without the flow control; 5) NLI231 injected into microcoil of 5% density without the flow control; 6) NLI231 injected into a microcoil of 10% density without the flow control. The microcoils were delivered to the embolization site, and NLI231 was injected. After 1 h of observation, distal filters were collected, and grades of migration (I = none, II = partial, III = almost all-all) were assessed for each scenario.

RESULTS

Embolization was achieved in scenarios with NLI231 and microcoils regardless of flow control (p < 0.01). NLI231 did not migrate in scenarios with microcoils and flow control (p < 0.05). NLI231 with microcoils without flow control can embolize the vessel, but partial migration occurred, and the distal distance of the NLI231 complex from the embolization site was longer (p < 0.01).

CONCLUSION

Combining sparse coiling with NLI231 may be feasible but is limited to use when flow control is available, or where distal embolization is permissible to some extent.

Prostate artery embolization using n-butyl cyanoacrylate glue for symptomatic benign prostatic hyperplasia: A six-month outcome analysis in 103 patients

PURPOSE

The purpose of this study was to assess the feasibility, safety, and 6-month outcomes of prostate artery embolization (PAE) using N-butyl-cyanoacrylate (NBCA) glue as the only embolic agent in patients with benign prostatic hyperplasia (BPH)-related lower urinary tract symptoms.

MATERIALS AND METHODS

Patients with BPH-related lower urinary tract symptoms who were treated by PAE using methacryloxysulfolane-NBCA mixed with ethiodized oil (1:8 ratio) between September 2018 and January 2023 were retrospectively included. Vascular mapping was made using cone-beam computed tomography angiography. PAEs were performed as an outpatient procedure, under local anaesthesia. Outcomes were assessed at six months using the International Prostate Symptoms Score (IPSS) and associated quality-of-life score (IPSS-QoL), prostate-specific antigen (PSA) level, prostate volume, and International Index of Erectile Function form 5 (IIEF5).

RESULTS

A total of 103 men with a mean age of 68.4 ± 6 (standard deviation [SD]) years were included. Technical success rate was 100%. The mean fluoroscopy time was 26.4 ± 12.5 (SD) min and the median radiation dose was 23 980 mGy·cm (Q1, Q3: 16 770, 38 450). Compared to baseline, statistically significant improvements were observed at six months for the IPSS (8.9 ± 6.2 [SD] vs. 20.2 ± 6.5 [SD]; P = 0.01), IPSS-QoL (2.1 ± 1.4 [SD] vs. 5.1 ± 0.9 [SD]; P = 0.01), PSA level (3.6 ± 3.2 [SD] ng/mL vs. 4.8 ± 4.2 [SD] ng/mL; P = 0.0001), and prostate volume (78.6 ± 43.5 [SD] mL vs. 119.1 ± 65.7 [SD] mL; P = 0.01). Minor adverse events developed in 19/103 (18.4%) patients. No major complications occurred. Compared to baseline, the IIEF5 did not change significantly at six months (15.3 ± 6.8 [SD] vs. 15.8 ± 6.8 [SD]; P = 0.078).

CONCLUSION

PAE with NBCA is a feasible and safe method that provides good outcomes at six months in patients with BPH-related lower urinary tract symptoms. This method deserves further evaluation in randomized trials with longer follow-up.

Polymerisation of cyanoacrylates: The effect of sclero-embolic and contrast agents

OBJECTIVES

The objective is to investigate the interaction of sclero-embolic and contrast agents with the polymerisation of medical grade n-butyl-cyanoacrylates.

METHODS

An in vitro spectrophotometric absorbance method was developed to detect changes in light transmission to measure n-BCA polymerisation. The initiation and the rate-of-polymerisation of mixtures of n-BCA with sclero-embolic and contrast agents were investigated.

RESULTS

Initiation of polymerisation: VENABLOCK™ and HISTOACRYL® were the fastest agents to polymerise, while VENASEAL™ was the slowest. Rate of polymerisation: Hypertonic saline inhibited the polymerisation of all n-BCAs, while hypertonic glucose prolonged the polymerisation rate. ETHANOL and detergent sclerosants had no effect. Contrast agents OMNIPAQUE™ and ULTRAVIST® initiated and prolonged the polymerisation of n-BCA, but in contrast, LIPIODOL® failed to initiate the process.

CONCLUSIONS

The commercially available medical cyanoacrylates differ in their polymerisation rates. These polymerisation rates are further affected when these products are used in conjunction with other compounds, such as sclero-embolic and contrast agents.

Endovenous glue ablation for chronic venous insufficiency: A comprehensive 5-year assessment of clinical and hemodynamic outcomes

OBJECTIVES

Chronic venous insufficiency is mainly caused by reflux, obstruction, or both. Endovenous glue ablation has become one of the widely used methods for treating reflux in recent years. Duplex ultrasonography is the most commonly used method for diagnosing and evaluating treatment. However, there is important information that plethysmographic venous hemodynamics provides, which Duplex USG cannot provide. This retrospective study aimed to evaluate the 5-year clinical, anatomical, and hemodynamic results of endovenous glue ablation in the treatment of chronic venous insufficience, accompanied by the data from the plethysmographic study.

PATIENTS AND METHOD

Between January 2018 and August 2018, 133 patients with symptomatic CEAP 2-6 varicose veins with reflux of the great saphenous vein lasting longer than 0.5 seconds and a diameter of 5.5 mm in the standing great saphenous vein underwent EVGA. CEAP, VCSS, CIVIQ 20, Doppler USG, GSV diameters and insufficiency times, and hemodynamically Venous Refilling Time and Venous Half-Value Time measurements were performed before the procedure. In the same way, measurements were made at the 1st, 3rd, 6th, 12th, 24th, and 60th months of the patients who were called and came to the postoperative follow-up.

RESULTS

Procedural success was 100%, and complete occlusion was observed %93 after treatment, at the 60 month. The improvement in VCSS (from 4.4 ± 1.3 to 1.7 ± 0.9), CIVIQ20 (from 8.5 ± 3.1 to 4.7 ± 2.0), VRT (from 20.3 ± 5.0 to 131.1 ± 4.0), and TH (from 2.8 ± 0.3 to 2.4 ± 0.2) was significant (p < .001 was for all).

CONCLUSION

Endovenous glue ablation is a preferred method for the treatment of great saphenous vein insufficiency due to its ease of use and the comfort it provides to patients, as well as its effectiveness and safety. In particular, it can be considered an effective method for improving venous hemodynamics and relieving associated symptoms.

Iodixanol as a New Contrast Agent for Cyanoacrylate Embolization: A Preliminary In Vivo Swine Study

N-butyl cyanoacrylate (NBCA) is a lipophilic, permanent embolic glue that must be opacified for fluoroscopic guidance. Empirically, lipophilic Lipiodol Ultra Fluid® (LUF) has been added to produce a single-phase physically stable mixture. Varying the dilution ratio allows control of glue polymerization kinetics. LUF is far more costly than water-soluble iodinated contrast agents (ICAs). Our purpose was to evaluate whether a water-soluble nonionic iso-osmolar ICA could be used instead. We embolized both renal arteries of six swine using 1:3 NBCA-LUF or NBCA-iodixanol in 1:1, 1:3, and 1:7 ratios. We used both micro-computed tomography to assess the distality of glue penetration and indexed cast ratio and histology to assess distality, arterial obliteration, vessel-wall damage, and renal-parenchyma necrosis. Glue-LUF produced significantly greater indexed cast ratio and renal-artery ROI values and a significantly shorter cast-to-capsule distance. The injected volume was significantly greater with 1:7 iodixanol than with the other mixtures. No significant differences were found for histological evidence of artery obliteration, vessel-wall damage, or renal-parenchyma necrosis. This is the first study dealing with ICA alone as a contrast agent for cyanoacrylate embolization, compared to LUF. More research is needed to determine whether water-soluble nonionic iodinated agents can be used for human NBCA embolization given the good safety profile, availability, and low cost of ICA.

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

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

Injectable Adhesive Hydrogels for Soft tissue Reconstruction: A Materials Chemistry Perspective

Injectable bioadhesives offer several advantages over conventional staples and sutures in surgery to seal and close incisions or wounds. Despite the growing research in recent years few injectable bioadhesives are available for clinical use. This review summarizes the key chemical features that enable the development and improvements in the use of polymeric injectable hydrogels as bioadhesives or sealants, their design requirements, the gelation mechanism, synthesis routes, and the role of adhesion mechanisms and strategies in different biomedical applications. It is envisaged that developing a deep understanding of the underlying materials chemistry principles will enable researchers to effectively translate bioadhesive technologies into clinically-relevant products.

In Vitro Evaluation of Acrylic Adhesives in Lymphatic Fluids-Influence of Glue Type and Procedural Parameters

To evaluate the embolic properties of different acrylic adhesive/iodized oil mixtures for lymphatic interventions. Polymerization of histoacryl (HA) (Bayer Healthcare) and glubran 2 (GL) (GEM) mixed with iodized oil (ratios 1:0–1:7) were investigated in lymphatic fluids with low and high triglyceride (low TG & high TG) contents. Static polymerization time and dynamic polymerization experiments with different volumes of glucose flush (1, 2 and 5 mL) were performed to simulate thoracic duct embolization. For both glues, static polymerization times were longer when the iodized oil content was increased and when performed in high TG lymphatic fluid. In the dynamic experiments, the prolongation of polymerization due to the oil content and TG levels was less pronounced for both glue types. Increased lymphatic flow rates decreased embolization times for low glue/oil ratios while preventing embolization for high glue/oil ratios. Higher glucose flush volumes increased occlusion times. Polymerization times of acrylic glue in a lymphatic fluid are prolonged by increasing the iodized oil concentration and triglyceride concentration as well as by using larger volumes of glucose flush. Increased lymphatic flow rates decrease embolization times for low glue/oil ratios and may prevent embolization for high glue/oil ratios.

NBCA-Lipiodol Mixture Embolization of Persistent Urine Leakage After Orthotopic Neobladder Formation: Techniques and Outcomes

Objective

To show the effective and successful technical approach of percutaneous embolization for persistent urine leakage that occurred after orthotopic neobladder formation.

Materials and Methods

We retrospectively reviewed patients who underwent percutaneous embolization of N-butyl cyanoacrylate (NBCA) and lipiodol mixture after orthotopic neobladder formation at the Seoul National University Hospital (Seoul, Korea) from 1 January 2018 to 31 December 2020.

Results

Among total of 182 patients of neobladder formation, five patients (four males and one female) were enrolled in this study, and their median age was 61.0 years (interquartile range (IQR): 42.5–69.5 years). All the patients showed persistent urine leakage at the neobladder-urethral anastomosis site and percutaneous drainage was primarily performed. The median time to perform percutaneous embolization was 40 days (IQR: 31.5–71.5 days) postoperatively. Elective two-staged embolization was performed in three cases for large diameter with a large fluid-filled cavity, while re-embolization was needed for delayed recurrence of urine leakage in two cases. Complete resolution of urine leakage was seen in all the cases and the median time to leakage closure was 55 days (IQR: 27.5–82.5 days). The median follow-up period after leakage closure was 26 months (IQR: 15.5–36.4 months), and embolization material-related bladder stone was a noticeable complication (two cases) during follow-up, which was removed endoscopically within 1 year after embolization. All patients' quality of life (EQ-5D-5L score) was well-maintained during the entire period.

Conclusions

Persistent urine leakage after neobladder formation can be effectively managed with percutaneous embolization of “dumbbell technique” by reinforcing the closure of leakage tract from inner opening to the outer opening even for large diameter (&gt;1 cm).

Management of Pancreatico-duodenal arterio-venous malformation

Purpose

To describe the interventional management and clinical outcome of pancreatico-duodenal arterio-venous malformations (PDAVMs).

Material and Methods

Seven patients presenting a PDAVM (6 women, 1 male; mean age: 61) were retrospectively reviewed. Technical, clinical success and complications of embolization and surgical management of symptomatic PDAVMs were assessed. Technical success was defined as a complete occlusion of the PDAVM and clinical success as no clinical symptom or recurrence during follow-up. Patients with asymptomatic PDAVMs were followed clinically, by Doppler ultrasound and CT-angiography.

Results

Mean follow-up time was 69 months (15-180). Five symptomatic patients presented with upper gastrointestinal bleeding (n=3), ascites (n=1), and abdominal pain (n=1). Two patients were asymptomatic. The PDAVMs were classified as follow: Yakes I (1), IIIa (2), IIIb (3) and IV (1). Five symptomatic patients were treated with 9 embolization sessions with arterial approach (onyx®, glue, coils) in 7 and venous approach in 2 (plugs, coils, covered stents, STS foam and onyx®). Technical success of embolization was 60% (3/5). Devascularization was incomplete for 2 Yakes IIIB patients. Clinical success of embolization was estimated at 80% (4/5) as one patient required additional surgery (Whipple) because of persistent bleeding. One splenic vein thrombosis was treated successfully by mechanical thrombectomy and heparin. No recurrence occurred during follow-up. No progression was documented in asymptomatic patients.

Conclusion

Embolization of symptomatic PDAVMs is effective and surgery should be performed in second intention. Complete devascularization is more difficult to obtain in Yakes III PDAVM.

Raman Spectroscopic Characterization of Polymerization Kinetics of Cyanoacrylate Embolic Glues for Vascular Embolization

Endovascular glue embolization is a minimally invasive technique used to selectively reduce or block the blood supply to specific targeted vessels. Cyanoacrylate glues, mixed with radiopaque iodized oil, have been widely used for vascular embolization owing to their rapid polymerization rate, good penetration ability and low tissue toxicity. Nevertheless, in clinical practice, the selection of the glue–oil proportion and the manual injection process of mixtures are mostly based on empirical knowledge of operators, as the crucial physicochemical effect of polymerization kinetics has rarely been quantitatively investigated. In this study, the Raman spectroscopy is used for studying the polymerization kinetics of n-butyl-cyanoacrylate-based glues mixed with an iodized oil. To simulate the polymerization process during embolization, glue–oil mixtures upon contact with a protein ionic solution mimicking blood plasma are manually constructed and their polymerization kinetics are systematically characterized by Raman spectroscopy. The results demonstrate the feasibility of Raman spectroscopy in the characterization of polymerization kinetics of cyanoacrylate-based embolic glues. The polymerization process of cyanoacrylate-based mixtures consists of a fast polymerization phase followed by a slow phase. The propagation velocity and polymerization time primarily depend on the glue concentrations. The commonly used 50% mixture polymerizes 1 mm over ∼21.8 s, while it takes ∼51 min to extend to 5 mm. The results provide essential information for interventional radiologists to help them understand the polymerization kinetics of embolic glues and thus regulate the polymerization rate for effective embolization.

In Vivo Experimental Endovascular Uses of Cyanoacrylate in Non-Modified Arteries: A Systematic Review

Cyanoacrylates were first used for medical purposes during World War II to close skin wounds. Over time, medical applications were developed, specifically in the vascular field. Uses now range from extravascular instillation in vascular grafting to intravascular injection for embolization. These applications were made possible by the conduct of numerous preclinical studies involving a variety of tests and outcome measures, including angiographic and histological criteria. Cyanoacrylates were first harshly criticized by vascular surgeons, chiefly due to their fast and irreversible polymerization. Over the past five years, however, cyanoacrylates have earned an established place in endovascular interventional radiology. Given the irreversible effects of cyanoacrylates, studies in animal models are ethically acceptable only if supported by reliable preliminary data. Many animal studies of cyanoacrylates involved the experimental creation of aneurysms or arteriovenous fistulas, whose treatment by endovascular embolization was then assessed. In clinical practice, however, injection into non-modified arteries may be desirable, for instance, to deprive a tumor of its vascular supply. To help investigators in this field select the animal models and procedures that are most appropriate for their objectives, we have reviewed all published in vivo animal studies that involved the injection of cyanoacrylates into non-modified arteries to discuss their main characteristics and endpoints.

Prostate Artery Embolization Using N-Butyl Cyanoacrylate Glue for Urinary Tract Symptoms Due to Benign Prostatic Hyperplasia: A Valid Alternative to Microparticles?

Our goal was to evaluate the feasibility, safety, and short-term outcomes of prostate artery embolization (PAE) with N-butyl cyanoacrylate (NBCA) glue as the only embolic agent in patients with benign prostatic hyperplasia (BPH)-related lower urinary tract symptoms (LUTSs). A two-center retrospective study of 50 patients (mean age, 67.6 ± 7.4 years; range, 54-85 years) treated with NBCA between 2017 and 2020 was conducted. PAE was performed using a mixture of Glubran 2 glue and Lipiodol in a 1:8 ratio, under local anesthesia, on an outpatient basis, after cone-beam computed tomography vascular mapping. Mean total injected NBCA/Lipiodol volume was 0.9 ± 0.3 mL, total injection time was 21.9 ± 7.8 s, and total radiation dose was 18,458 ± 16,397 mGy·cm. Statistically significant improvements over time occurred for the International Prostate Symptoms Score (9.9 ± 6.8 versus 20.5 ± 6.7, p = 0.0001), quality-of-life score (2.2 ± 1.5 versus 4.9 ± 1.0, p = 0.0001), prostate-specific antigen level (4.6 ± 3.0 versus 6.4 ± 3.7, p = 0.0001), and prostate volume (77.3 ± 30.5 versus 98.3 ± 40.2, p = 0.0001) at a median of 3 months versus baseline. Minor adverse events developed in 11/50 (22%) patients, but no major complications occurred. The International Index of Erectile Function did not change significantly. PAE with NBCA is feasible, safe, fast, and effective for patients with BPH-related LUTSs. Prospective comparative studies with longer follow-ups are warranted.

In Vivo Animal Study of a Highly Viscous N-butyl Cyanoacrylate Medical Adhesive for Intravenous Embolization

N-butyl cyanoacrylate (NBCA) is a liquid monomer that undergoes an exothermic polymerization reaction to form a solid upon initiation with hydroxyl anions. Recently, EGpresto, a highly viscous NBCA-based adhesive, has been developed for vascular-occlusion purposes. In this study, we investigated the heat of polymerization of EGpresto and compared the results with those of a low-viscosity NBCA glue. Results show that EGpresto exhibited a lower heat of polymerization (64 ± 7 °C vs. 34 ± 1 °C). This was due to its high viscosity, which resulted in a delayed polymerization time. To investigate the efficacy and safety of EGpresto for intravenous embolization, a 14 d in vivo animal test was conducted using three pigs. Five cc of EGpresto was injected into the epigastric vein of each animal. Complete postoperative vein occlusion was confirmed at 7 and 14 d by ultrasonographic visualization. After the animals were sacrificed, the operated and unoperated veins were exposed, and the injected adhesive was found without migration. During the histology, the injected adhesive was not found in the inner or outer vein walls, and the immune reactions seemed to be the only foreign-body reaction, showing that EGpresto is a non-toxic and safe intravascular embolic agent.

Feasibility and safety of a new endoscopic synthetic sealant nebulizing device over gastric endoscopic submucosal dissections

Background

Endoscopic Submucosal Dissection (ESD) is the treatment of choice of superficial neoplastic gastrointestinal lesions. Delayed bleedings and perforations are still current clinical concerns. Glubran 2 is a synthetic cyanoacrylate-derived glue nowadays already widely used as an effective tissue adhesive. ENDONEB is a novel device thought for enabling the sealant nebulization over a specific targeted surface during laparotomy, laparoscopy, and thoracotomy. The aim of this single-center preclinical animal trial is to evaluate the feasibility and safety of the same nebulization technique during ESD in the perspective that further clinical studies would demonstrate the efficacy of Glubran 2 in preventing post-ESD adverse events.

Methods

Four live Landrace pigs were enrolled. Two approximately 30-mm-wide gastric ESDs were performed in each pig (experimental ESD and control ESD). About 0.5 mL of Glubran 2 was nebulized on the experimental ESDs. Subjective perception of the feasibility of the Glubran 2 nebulization was reported. Pigs were clinically monitored at follow-up and upper GI endoscopy was performed at 24 and 48 hours, when animals were euthanized to perform a macroscopic and histological analysis of the specimens.

Results

No peri-procedural adverse events were reported. Glubran 2 nebulization over experimental ESDs showed to be technically easy and time-effective. Clinical and endoscopic animal monitoring was negative at follow-up. At 24 hours, the Glubran 2 film was clearly visible on the eschar of the ESDs and signs of initial hydrolysis were discernable at 48 hours. No signs of peritoneal reaction were observed at the macroscopic examination. Equal transmural inflammation was described at the histological examination of both types of ESDs.

Conclusions

Safety and feasibility profiles of Glubran 2 nebulizing ENDONEB device over ESD surfaces were excellent. Further evidences and human trials are needed to investigate its effectiveness in ESDs’ eschars sealing and, thus, in delayed micro-perforations and bleedings prevention and treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00464-021-08480-4.

Development of electrospun core-shell polymeric mat using poly (ethyl-2) cyanoacrylate/polyurethane to attenuate biological adhesion on polymeric mesh implants

Poly (ethyl-2) cyanoacrylate was used to create an adhesion-free biocompatible non-woven material reinforced by polyurethane core via a co-axial electrospinning set-up. The effect of relative humidity (RH) of (18, 30, 40, 60, and 68) % on the electrospinning process was examined, and found that in order to achieve well defined core-shell fiber structure, the optimal RH was 18%. If the RH is >18%, a phenomenon called Taylor cone cyclic destabilization occurs, which results in unfavorable surface and mechanical properties of the mat. The developed composite electrospun mat has the potential to be used in medical devices, such as repairing the viscera layer for intraperitoneal hernia mesh implants, which require the attenuation of biological elements, and adequate mechanical properties.

Sustained volume decreases in simple renal cysts after sclerotherapy using NBCA with or without hydrodissection

The present study aimed to determine the effectiveness of sclerotherapy using NBCA (Histoacryl Blue®; B. Braun, Melgungen, Germany), with or without hydrodissection, for the treatment of simple renal cysts. Materials and Methods: Patients who presented to an interventional radiology clinic for the diagnosis of symptomatic renal cysts which had previously been identified at an outpatient clinic were selected for inclusion in this study. A total of 28 patients were randomly divided into 2 groups, based on whether or not they underwent hydrodissection along with ultrasound-guided NBCA-based sclerotherapy. Sonographs were performed at 0, 7, and 180 days post-procedure to record the residual volume of the renal cysts and to determine the efficacy of the procedure. Results: A total of 32 cysts in 28 patients were treated with sclerotherapy, 18 (64%) females and 10 (36%) males. The average age of the patients was 61.8 years (range: 33-89 years). All patients reported an improvement in symptoms associated with the existing renal cysts at 7 and 180 days post-procedure, and at 7 days post-procedure a statistically significant reduction in cyst volume was observed (all patients: 96.8%; group A: 96%; group B: 97.6%). The reduced cyst volume was still observed 180 days post-procedure (all patients: 98.6%; group A: 98.2%; group B: 98.9%). There was no significant difference between the two treatment groups. Conclusion: There is a significant and persistent reduction in the volume of renal cysts, in addition to an improvement of the associated symptoms, after treatment with NBCA-based sclerotherapy, with or without hydrodissection.

Comparing N-hexyl cyanoacrylate (Magic Glue) and N-butyl cyanoacrylate (NBCA) for neurovascular embolization using the pressure cooker technique: An experimental study in swine

BACKGROUND

The pressure cooker (PC) technique uses a second microcatheter to produce a proximal occlusion to prevent the reflux of liquid embolic agent (LEA) injected through a more distal microcatheter, and can be used to treat arteriovenous malformations and dural arteriovenous fistulae. The liquid embolic Magic Glue (MG) (N-hexyl cyanoacrylate (NHCA)) has been introduced as an alternative to N-butyl cyanoacrylate (NBCA). Our goals were to compare the extent of embolization of rete mirabile with or without the PC technique using NBCA or MG, and to compare the proximal occlusions obtained with MG or NBCA while using the PC technique in a renal arterial model.

METHODS

Rete mirabile were embolized with (n = 4) and without (n = 4) the PC technique, using MG (n = 4) or NBCA (n = 4). A renal arterial model was then used to study the characteristics of the MG plug (n = 10) used for the PC technique, and resistance to catheter withdrawal as compared to NBCA (n = 4). Specimens were analyzed macro- and microscopically and compared to angiographic results.

RESULTS

Extent of rete embolization with CYA agents was not significantly greater when using the PC technique. Results were similar with both types of cyanoacrylate (p = 0.657). The force necessary to withdraw the microcatheter was less with MG than with NBCA (p = 0.035).

CONCLUSION

MG was similar to NBCA in extent of rete embolization. Less traction force was necessary to withdraw trapped non-detachable microcatheters using MG compared to NBCA.

Comparison of Cost and Efficacy of Trufill® vs Histoacryl® n-Butyl Cyanoacrylate for Translumbar Type 2 Endoleak Embolization

PURPOSE

The study aimed to compare the cost and efficacy of translumbar approach type 2 endoleak repairs using either Trufill® or Histoacryl® n-BCA liquid embolic.

METHOD AND MATERIALS

This was a retrospective review of patients who had translumbar approach type 2 endoleak repairs using either Trufill® or Histoacryl®. Patients were included if they underwent a technically successful type 2 endoleak repair via a translumbar approach with Trufill® or Histoacryl® n-BCA. A multivariable analysis was performed with the primary clinical outcome of percent change in aneurysm diameter per month compared. Procedure cost was calculated based on typical materials used.

RESULTS

20 Trufill® and 14 Histoacryl® patients were included. The mean procedure cost was higher for Trufill® ($5,757.30 vs. $1,586.09, p ≤ 0.001). There was no significant difference between Trufill® or Histoacryl® patients for age at first embolization, gender, total number of embolizations, number of feeding branches, aneurysm sac size prior to embolization, or residual endoleak at first follow-up. Trufill® patients had more coils used (12.0 vs. 4.3, p = 0.0007), less glue used (0.9 vs. 2.1 mL, p < 0.001), longer follow-up duration (33.5 vs. 13.2 months, p = 0.002), more follow-up CT angiograms (CTA) (3.7 vs. 1.9, p = 0.01), and larger excluded aneurysm sac size at most recent CTA (7.1 cm vs. 5.9 cm, p = 0.04). Percent change in sac diameter per month was not significantly different between Trufill® and Histoacryl® (0.21% vs. -0.25%/month, p = 0.06, respectively). There were no complications.

CONCLUSION

Use of Histoacryl® over Trufill® n-BCA resulted in significantly less procedural cost while maintaining safety and efficacy.

Use of confocal Raman microscopy to characterise ethyl cyanoacrylate adhesive depth curing

In situ spatial temporal measurement of monomer conversion during adhesive bondline curing remains a challenging area. The aim of this work was to demonstrate the effectiveness of using confocal Raman microscopy in a specially configured experimental set-up, as a versatile tool for measuring monomer concentration changes as a function of both time and adhesive bond depth during ethyl cyanoacrylate polymerisation. This also allowed monitoring of the extent of polymerisation at the adhesive substrate interface independently of the bulk bondline polymerisation region. Key kinetic parameters such as inhibition time t_lag, rate of reaction R_max and extent of reaction [α_t]_max were obtained by fitting the experimental data to sigmoidal growth curves using simple piecewise regression models. A systematic characterisation of a polymerisation reaction was conducted using different sample substrate types (copper alloy (red brass), aluminium, aluminium alloy, stainless steel and borosilicate glass) and at various reaction temperatures. Reaction rates were found to decrease further away from the substrate interface in the bulk volume region. The fastest kinetics occurred in the vicinity of nucleophilic hydroxyl rich surfaces such as at the copper alloy (red brass). In addition to substrate surface chemistry, surface roughness was also a factor, with the highest reaction rates occurring with a grit blasted (roughened) aluminium alloy (2024 T3) surface. An approximately linear dependence of the ln R_maxvs. 1/T (Arrhenius) plot was recorded within the temperature range of 291-328 K. A better fit was obtained however through the use of two separate linear slopes, possibly indicative of a change of polymerisation reaction mechanism taking place at elevated temperatures with two distinct activation energies. Further work conducted using a larger number of temperatures would be useful to verify this finding. This work confirmed that differences in the rates of interfacial and bulk polymerisation processes could be readily measured in situ using confocal Raman microscopy which is a powerful technique for investigating such surface-confined and bulk polymerisation reactions.

A giant symptomatic placental chorioangioma managed with a histoacryl injection

Chorioangiomas are generally small and associated with favorable outcomes, but large tumors can cause serious fetal complications, such as polyhydramnios, fetal anemia, intrauterine growth restriction, cardiac failure, fetal hydrops, and intrauterine fetal death. Signs of fetal cardiac failure on ultrasonography are indications for urgent in utero interventions. We report a case of a giant chorioangioma causing fetal cardiac failure at 26⁺³ weeks' gestation, which was treated by embolization of the feeding vessels. We utilized a mixture of n-butyl cyanoacrylate (nBCA, Histoacryl®) and iodized oil (Lipiodol®) as an embolic agent. Fetal hydrops resolved in 4 weeks, and the cardiac size and function normalized 8 weeks after the embolization. A healthy male baby was born at the 37⁺⁵th gestational week by cesarean section.

The combination of balloon-assisted antegrade transvenous obliteration and transjugular intrahepatic portosystemic shunt for the management of cardiofundal varices hemorrhage

OBJECTIVES

In this study, we propose a modified balloon-occluded retrograde transvenous obliteration (BRTO) strategy - balloon-assisted antegrade transvenous obliteration (BAATO), and explore the feasibility, efficacy and safety of BAATO combined with transjugular intrahepatic portosystemic shunt (TIPS) in the treatment of cardiofundal varices (GOV2 or IGV1) hemorrhage.

MATERIALS AND METHODS

In this retrospective cohort study, 15 patients with cardiofundal varices hemorrhage who received BAATO combined with TIPS procedures, from August 2017 to September 2019 in our center, were enrolled. They consisted of seven patients with GOV2 and eight patients with IGV1. The clinical efficacy and safety of BAATO + TIPS procedures were assessed by comparing the clinical symptoms, laboratory and imaging examinations before and after treatment.

RESULTS

The technical success rate of BAATO + TIPS procedure was 100%. After the procedure, clinical symptoms were improved and complete regression of gastric varices (GVs) was observed in all patients, besides, the control efficiency of ascites and PVT which were 77.8 and 87.5%, respectively. No patient died or had a rebleeding during the follow up, but grade II hepatic encephalopathy (HE) occurred in two patients (13.3%) and shunt dysfunction was discovered in one patient (6.7%).

CONCLUSION

For the treatment of GVs, the new technique BAATO is feasible, safe and effective, and it may be a more convenient and economical method than conventional BRTO. In addition, the combination of BAATO and TIPS may play a positive role in achieving hemostasis and improving the complications of portal hypertension such as ascites and PVT.

Combination therapy versus monotherapy for EUS-guided management of gastric varices: A systematic review and meta-analysis

Cyanoacrylate (CYA), coil embolization, and/or combination thereof are available EUS-guided therapies for the treatment of gastric varices (GV). The primary aim of this study was to perform a structured systematic review and meta-analysis to evaluate the comparative effectiveness of EUS-guided interventions for the treatment of GV. Individualized search strategies were developed for PubMed, EMBASE, and Cochrane Library databases, from inception through November 2018 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. This cumulative meta-analysis was performed using calculating pooled proportions. Measured outcomes included technical success, clinical success, adverse events, and rate of rebleeding or reintervention. Comparative subgroup analyses were performed for three treatment cohorts (EUS-guided CYA injection, EUS-guided coil embolization + CYA injection, and EUS-guided coil injection alone). Heterogeneity was assessed with I² statistics. Eleven studies (n = 536 patients; 62.20% of males) were included. The mean age was 58.21 ± 4.15 years with an average follow-up of 12.93 ± 7.69 months. Overall technical success, clinical success, and adverse events for EUS treatments was 100% ([95% confidence interval [CI] 98–100]; I² = 30.54%), 97% ([95% CI 92–100]; I² = 59.99%), and 14% ([95% CI 6–23]; I² = 82.23%), respectively. On subgroup analysis, EUS-guided CYA + coil embolization resulted in a better technical and clinical success compared to CYA alone (100% vs. 97%; P < 0.001 and 98% vs. 96%; P < 0.001) and coil embolization alone (99% vs. 97%; P < 0.001 and 96% vs. 90%; P < 0.001). CYA + coil embolization also resulted in lower adverse event rates compared to CYA alone (10% vs. 21%; P < 0.001), and comparable rates to coil embolization alone (10% vs. 3%; P = 0.057). EUS-guided treatment overall appears to be an effective and safe modality for GV. Among a variety of EUS-therapies available, EUS combination therapy with coil embolization + CYA injection appears to be a preferred strategy for the treatment of GV over EUS-based monotherapy.

Successful Balloon-Occluded Retrograde Transvenous Obliteration for Gastric Varices Using Foam Sclerosant Followed by Glue Embolization of Gastrorenal Shunt via the Brachial Vein Approach in a Severely Obese Patient

Balloon-occluded retrograde transvenous obliteration is an effective treatment for gastric varices. In this report, we illustrate a consecutive treatment strategy via brachial vein approach and n-butyl cyanoacrylate (NBCA) packing of the gastrorenal shunt (GRS) after injecting sclerosing agent in a severely obese patient. The brachial vein approach reduced the burden on the patient, and the closure of the GRS using NBCA shortened the procedure time. These techniques may improve patient comfort as well as reduce medical costs and the risks of several complications.

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.

Comparison between Polybutylcyanoacrylate Nanoparticles with Either Surface-Adsorbed or Encapsulated Brain-Derived Neurotrophic Factor on the Neural Differentiation of iPSCs

The brain-derived neurotrophic factor (BDNF) is vital in the neural differentiation of neural stem/progenitor cells, and together may have therapeutic potential for neural regeneration. In this study, a multiplexed polybutylcyanoacrylate nanoparticle (PBCA NP) delivery platform was constructed, incorporating either surface-adsorbed or encapsulated BDNF for the induction of neural differentiation in induced pleuripotent stem cells (iPSCs), where tween 80 (T80) and superparamagnetic iron oxide (SPIO) were added for central nervous system (CNS) targeting and magnetic resonance (MR) image tracking, respectively. Both methods by which the BDNF was carried resulted in loading efficiencies greater than 95%. The nanoparticle-mediated delivery of BDNF resulted in neural differentiation of iPSCs detected on immunofluorescence staining as early as 7 days, with enhanced differentiation efficiency by 1.3-fold compared to the control on flow cytometry; the delivery system of surface-adsorbed BDNF gave rise to cells that had the best neural development than the encapsulated formulation. T80-coating disrupted the in vitro blood–brain barrier model with a corresponding 1.5- to two-fold increase in permeability. SPIO-loaded PBCA NPs exhibited a concentration-dependent, rapid decay in signal intensity on the phantom MR experiment. This study demonstrates the versatility of the PBCA NP, and the surface-adsorption of BDNF is the preferred method of delivery for the differentiation of iPSCs.

Treating great and small saphenous vein insufficiency with histoacryl in patients with symptomatic varicose veins and increased risk of surgery

BACKGROUND

Treating great and small saphenous vein trunk insufficiency with cyanoacrylate glue is the least taxing treatment method of all available techniques. Due to long-term unavailability of commercial kits with n-butyl-2-cyanoacrylate (histoacryl) in the Czech Republic, we used a modified technique.

PATIENTS AND METHODS

Fifty-six limbs in 49 patients suffering from great saphenous vein or small saphenous vein insufficiency in combination with symptomatic chronic venous insufficiency and complicating comorbidities were treated with a modified endovascular cyanoacrylate glue application technique.

RESULTS

The immediate success rate of the treatment was 98 %. In follow-up intervals of six weeks, six months, one year, and two years, the anatomical success rates of embolization (recanalization of no more than 5 cm of the junction) were 98, 96, 94, and 94 %, respectively. At identical intervals the venous insufficiency was scored according to the Aberdeen Varicose Vein Questionnaire and the American Venous Clinical Severity Score. In both cases, improvement was demonstrated over the two-year follow-up, with a 0.5 % significance level. Specific clinical signs of venous insufficiency were also evaluated, such as pain, oedema, clearance of varicose veins, and healing of venous ulceration. One severe complication - a pulmonary embolism - was reported, without consequences.

CONCLUSIONS

We demonstrated that treating insufficient saphenous veins with modified histoacryl application brought a relief from symptoms of venous insufficiency and that the efficiency of this technique is comparable to commonly used methods.

Embolization as the Primary Treatment for Mandibular Arteriovenous Malformations: An Analysis of 50 Literature Reports and of an Illustrative Case

PURPOSE

The aim of the present report is to describe 50 cases in the literature of mandibular arteriovenous malformations (AVMs) in which embolization was the primary treatment and to discuss details such as age, gender, materials used, outcome of embolization, time of follow-up, and intra- or postprocedure complications. An illustrative case in which reossification was noticed after embolization also is presented.

PATIENTS AND METHODS

The study was carried out in 2 steps. In the first, an electronic search without time restriction for embolization as the primary treatment for mandibular AVMs was performed on Medline through PubMed. In the second, the case of a patient with mandibular AVM and massive oral bleeding episodes is described after a long-term follow-up.

RESULTS

Clinical stability with the cessation of oral bleeding episodes was detected in 25 cases and 2 cases were planned for another embolization session. Clinical stability and reossification were detected in 23 of the 50 cases included. Complications were reported in 50% of cases, but most were minor and transient.

CONCLUSION

Currently, owing to more sophisticated imaging techniques, the diagnosis of mandibular AVMs is quicker and new, less invasive techniques that avoid surgical resection have proved effective. It should be emphasized that these techniques are not without complications and that long-term monitoring is extremely important.

Polymerization kinetics of a mixture of Lipiodol and Glubran 2 cyanoacrylate glue upon contact with a proteinaceous solution

The Glubran 2 cyanoacrylate glue is a liquid embolic agent used to block blood vessels endovascularly. Typically mixed with an iodized oil (Lipiodol) for visualization under X-ray, it polymerizes when in contact with blood and tissues owing to the presence of ions and proteins. The objective of the study is to determine the influence of plasma proteins in the polymerization reaction. A triggering solution containing bovine serum albumin (BSA) and the main blood ions is used as a model of plasma. The polymerization kinetics of Glubran 2-Lipiodol mixtures is measured upon aspiration in a capillary tube and contact with the proteinaceous solution. Having varied the glue and protein concentrations, we show that glue-Lipiodol mixtures with concentrations larger or equal to 25% polymerize when put in contact with an ionic solution containing at least 4% of BSA. The reaction is decomposed into two phases: a fast zwitterionic polymerization induced by the BSA molecules followed by a slower polymerization phase. The reaction speed and extent of the solidification region mostly depend on the glue concentration. The time for the glue solution to polymerize over a 1mm thickness varies from 5s for pure glue to about 1min for a 50% glue concentration, and 10min for a 25% glue mixture. It is the first time that the kinetics of the two polymerization reactions is quantified for Glubran 2, which will provide the information needed by interventional radiologists to optimize the planning of endovascular glue injection.