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

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.

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.

Managing gastric varices

Gastric varices (GV) are a type of ectopic varix, which is a natural portosystemic shunt occurring in response to an increase in intrahepatic vascular resistance, mostly commonly from portal hypertension. GV are present in up to 20% of patients with portal hypertension. Although oesophageal varices are more common than GV, and oesophageal variceal bleeding (EVB) happens more often than gastric variceal bleeding (GVB), GVB tends to be more severe, to have higher associated hospital costs, length of stay, higher rebleeding rates and have higher mortality. Mortality rates associated with variceal bleeding range from 6% in EVB to 20%-55% in GVB. Risk factors for GV haemorrhage include location, size, severity of liver failure, presence of variceal red spots, and presence of HCC (hepatocellular carcinoma). This manuscript will review endoscopic and non-endoscopic treatment of GV.

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.