Homologous controlled-viscosity fibrin for endovascular embolization. Part II: catheterization technique, animal experiments

Liquid Embolic Agents for Endovascular Embolization: A Review

Endovascular embolization (EE) has been used for the treatment of blood vessel abnormalities, including aneurysms, AVMs, tumors, etc. The aim of this process is to occlude the affected vessel using biocompatible embolic agents. Two types of embolic agents, solid and liquid, are used for endovascular embolization. Liquid embolic agents are usually injectable and delivered into the vascular malformation sites using a catheter guided by X-ray imaging (i.e., angiography). After injection, the liquid embolic agent transforms into a solid implant in situ based on a variety of mechanisms, including polymerization, precipitation, and cross-linking, through ionic or thermal process. Until now, several polymers have been designed successfully for the development of liquid embolic agents. Both natural and synthetic polymers have been used for this purpose. In this review, we discuss embolization procedures with liquid embolic agents in different clinical applications, as well as in pre-clinical research studies.

Polymeric materials for embolic and chemoembolic applications

Percutaneous transcatheter embolization procedures involve the selective occlusion of blood vessels. Occlusive agents, referred to as embolics, vary in material characteristics including chemical composition, mechanical properties, and the ability to concurrently deliver drugs. Commercially available polymeric embolics range from gelatin foam to synthetic polymers such as poly(vinyl alcohol). Current systems under investigation include tunable, bioresorbable microspheres composed of chitosan or poly(ethylene glycol) derivatives, in situ gelling liquid embolics with improved safety profiles, and radiopaque embolics that are trackable in vivo. This article reviews commercially available materials used for embolization as well as polymeric materials that are under investigation.

False aneurysms of the intracavernous carotid artery--report of 7 cases

We present 7 cases of false intracavernous carotid artery aneurysms. Four occurred after trauma and three were caused iatrogenically. Two of the latter occurred in patients with pituitary adenomas, one after transsphenoidal microsurgery and the other after yttrium [YI90] seed implantation into the sella. The third iatrogenic aneurysm was seen shortly after transcavernous tumour surgery. In five of our seven patients massive, delayed, life-threatening epistaxis was the leading symptom. All traumatic cases were associated with immediate unilateral blindness or blurred vision and with skull base fractures. One of these had a concomitant carotid cavernous fistula. Treatment of choice of our 5 recent cases was permanent balloon occlusion of the intracavernous carotid artery at the level of the lesion. Collateral circulation was evaluated prior to definitive carotid occlusion using a balloon test occlusion. During the balloon test adequate collateral circulation was defined as symmetric angiographic filling of both hemispheres. Awake patients were neurologically examined continuously. In unconscious patients transcranial Doppler sonography, electroencephalographic and somatosensory evoked potential monitoring was used in addition. Intra-operative heparin administration was not reversed with protamin. A postoperative continuous heparin infusion was not found necessary. In our two early cases this technique was not available: In the first case we accomplished aneurysm occlusion by a surgically introduced Fogarty balloon catheter. Our second patient needed surgical trapping of the involved carotid after early unsuccessful attempts of selective aneurysm occlusion. After treatment no further epistaxis occurred. Follow-up angiography showed persistent aneurysm occlusion. The results were excellent in 5 cases and good in 1 case. One patient with bilateral lesions suffered a stroke after occlusion of the second, remaining carotid artery, despite functioning bilateral extra-intracranial bypasses. Four years later there is a mild dysphasia still present in this patient. The mean follow-up time was 75.6 months.

Barium-impregnated fibrin glue: application to a bleeding duodenal sinus

A 64-year-old man with Crohn's disease who had undergone repair of an ileovesical fistula and ileoileostomy had numerous postoperative complications related to sepsis and wound healing. Subsequently, upper gastrointestinal bleeding developed, and the site was identified as a duodenal sinus. Medical management was unsuccessful in controlling the bleeding. Because of the considerable risk associated with reoperation in this seriously ill patient, approval was obtained from the Food and Drug Administration to use fibrin glue in an attempt to prevent further bleeding. The glue was mixed with barium and placed in the duodenal sinus under endoscopic guidance. The barium-impregnated glue facilitated follow-up surveillance with abdominal roentgenography. The patient had no further gastrointestinal bleeding. Further clinical and experimental studies should be conducted to determine the mechanism of action and the efficacy of this application of fibrin glue.