Particulate embolic agent

Particulate embolic agents are typically used for the embolization of tumor and tumor-related symptoms in addition to the treatment of certain hemorrhagic conditions. In general, these agents are administered from a selective position within the arterial vasculature of the target organ and are subsequently... 

Spigos et al. [112] adopted a strict protocol that resulted in a remarkably low number of complications. The protocol included broad-spectrum antibiotics started 8-12 hours before the procedure and continued for 1-2 weeks, local antibiotics (such as gentamicin) suspended in the solution used to deliver the particulate embolic agents and administered through the angiographic catheter, strict attention to sterility (whole-body povidone-iodine bath or wide surgical scrub at the site of catheter insertion), selective catheterization with the catheter tip beyond pancreatic branches, effective pain control with narcotics or epidural anesthesia for 48 hours (which prevents the splinting that may... 

The stomach and duodenum have a rich collateral blood supply and hence embolization of branches of the coeliac axis can be performed with a low risk of infarction of the viscera. Conversely, the extensive vascular supply may make embolization more difficult to achieve. Thus, in addition to coils, a small particulate embolic agent is often required for a more distal block. A co-axial catheter system is likely to be necessary for this. The method of embolization depends on the angiographic findings but occlusion of the artery needs to be performed on either side of the abnormality (eroded artery or aneurysm) to achieve haemostasis. Ischaemia may be provoked... 

The key decision in the performance of any embolization procedure is the choice of agent. Based on their physical and chemical properties, embolic agents can induce mechanical occlusion of the vessels provoke the formation of thrombus by inflammatory reactions or destroy the endothelium leading to thrombosis. In this section, we will discuss the particulate agents, liquid agents and metallic embolic materials. 

Chemoembolization has also been performed in an attempt to improve upon the results obtained with particulate embolization alone. Microencapsulated cisplatin particles (100 pm in diameter) were prepared at MDACC by a solvent evaporation technique and contained 46% by weight of cisplatin and poly(D,L)-lactide. In a 1 1 ratio of chemotherapeutic agent to capsular material, approximately 40% of the cisplatin was released within the first 4 h after delivery, as determined by in vitro studies. A Phase I/II Clinical study was performed at MDACC in 20 patients utilizing microcapsules containing cisplatin 100 mg/m as the maximum tolerated dose (MTD), delivered every 4-6 weeks. The median number of vascular occlusion procedures per patient was three. Of the 18 evaluable patients, 12 (67%) had a PR in their symptoms. Of the 15 patients with elevated 5-hydroxyindoleacetic acid, 11 (73%) had a median reduction of 64%. In 14 of 18 patients there was an objective decrease in the tumor, of which six (33%) were PR and eight (44%) were MR. One treatment-related death occurred from hepatorenal syndrome and five (25%) of the 20 patients died of the disease during the study (Diamandidou et al. 1998). 

The size and extent of the tumor, the need to preserve any of the renal parenchyma, and the overall goal of embolization should be considered in planning embolotherapy of renal tumors. Historically, the choice of embolic agents depended on the experience and preference of the operator. Although more than twenty embolic agents have been used (Table 16.2), it is most worthwhile to consider three classes of embolic agents currently used for embolizations of renal tumors liquid agents (the prototype of which is absolute ethanol), particulate materials (the prototype of which is polyvinyl alcohol foam), and metallic coils. 

If structural abnormalities such as vascular malformations, hypervascular tumors, vessel wall irregularities suggesting erosion etc., are visualized, then we may try for a palliative embolization with Gelfoam or particulates. Rarely, curative embolization of an arteriovenous malformation or fistula is achievable with non-resorbable agents, such as glue or detachable balloons. 

Distal embolization is achieved with particulate agents, cyanoacrylate or other liquid agents. Proximal ligation is surgically performed or may be done percutaneously with steel coils or detachable balloons. Considering that the intrahepatic portal vasculature was classically considered as terminal... 

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