Embolization Subject

If it is not dissolved or trapped, an embolism moving from the lower extremities can be life-threatening. People afflicted with phlebitis are particularly susceptible to this problem. A shape-memory trap has been devised that, when deployed in the vena cava, is like a multileaved mesh that traps a traveling embolism, retaining it until medication can dissolve it. Introduced in a folded form by a catheter, the mesh is prevented from deploying by subjecting it to a flow of cold saline water. Once in place, it is released from the catheter and, warmed by body heat, opens into its final shape (11). 

Several reviews of the adverse effects of vitamin E have been published (3,4), especially relating to premature infants (5), in whom high doses have been associated with infectious complications and fatal hepatic failure. In adults, thrombophlebitis, thromboembolism, pulmonary embolism, hypertension, fatigue, gynecomastia, and breast tumors have been described as particularly serious effects of vitamin E, but there is little evidence about their frequency. Diarrhea and abdominal pain can occur. For some of these effects there seems to be a dose relation. A dose of 800 mg/day for 30 days had no reported adverse effects in healthy elderly subjects (6). Table 1 shows reported adverse effects related to dosage in a review of about 50 publications on vitamin E (7). 

The use of an appropriate mammalian species for biocompatibility studies often has been a topic of heavy debate. The rationale for use of the dog in our system was based primarily on availability of subjects and cost. In addition, the adherence of dog platelets to cuprophane membranes was reported to be three orders of magnitude greater than the adherence of human platelets (41). The dog is also thought to have a highly potent fibrinolytic system (42). Thus, the dog should be a very sensitive animal for studying clot formation and dissolution. A clearer visualization of the mechanisms involved should therefore be possible. We believe that fundamental mechanisms underlie artificial surface-induced thrombosis and embolization in dogs, humans, and other mammalian species. 

The use of oral contraceptive agents (OCAs) is widespread and is being increasingly encouraged in developing countries. Their use has been associated with a number of side effects, in particular, a possible increased risk of thrombotic and embolic vascular disease. There is also evidence that OCAs may affect the metabolism of a number of vitamins. Evidence for deficiency of thiamine, riboflb vin, ascorbic acid, pyridoxine, folic acid, and vitamin B12, and for excess accumulation of vitamin A has been reported. This is of particular concern to populations in which vitamin nutrition may already be suboptimal and has been the subject of recent brief reviews (02, R4, Tl, W13). 

Polyvinyl alcohol (PVA) particles have been used in a number of series [6,10,17-20). The particles need to be suspended in iodinated contrast since PVA is not intrinsically radio-opaque otherwise it is not possible to fluoroscopically monitor the embolization. Because the PVA is flow directed, delivery of this embolic agent is less precise than with coils and more subject to local hemodynamics. If the catheter is obturating the feeding artery, the particles will not flow away as readily. Also as the vessel starts to become ocduded by the PVA, the resistance to flow increases and hence the potential for reflux to nontarget segments of bowel will increase. 

In previous cases, identified by specific searching, one subject had two known risk factors for pulmonary embolism (obesity and a recent ankle fracture), one had one risk factor (obesity), and three had none. 

Embolization, by definition, reduces blood flow distally. Therefore, it is no surprise that distal necrosis is a recognized complication of trauma embolization. However, unintentional reflux of embolization material from the internal iliac into the femoral artery can cause inadvertent ischemia in the leg. Sciatic palsy with associated foot drop and sacral plexus palsy has been reported [57]. Embolization of the superior gluteal artery in a patient vdio will be subjected to prolonged bedrest may cause sacral and buttock ischemia leading to skin break down [58]. Sexual dysfunction seems not to he a complication of bilateral internal iliac artery embolization, but is more likely a result of nerve injury secondary to the fracture or pelvic trauma [59]. 

Several variables have been considered in measurement of the intended outcome, including intraoperative blood loss. Twelve studies evaluated intraoperative blood loss after renal artery embolization. In three studies, blood loss was based on subjective estimation only [48-50]. One study compared... 

A variety of clinical states are associated with thrombosis. The present discussion is limited to a few of the more prominent thromboembolic diseases further Information on this subject may be found in several reviews.3,7-9 The most common clinical states which Involve clot-like, venous thrombi are deep vein thrombosis, particularly as a postsurgical complication, and pulmonary embolism. Anticoagulants such as heparin and the coumarins have been known for years to be effective in the prevention of these types of thrombi and more recent experience has demonstrated the efficacy of fibrinolytic agents such as streptokinase for their dissolution.3,9 Platelet aggregation Inhibitors have only recently been evaluated clinically in the prevention of venous thrombosis. These studies are crucial to the resolution of the controversy as to whether platelets play a vital role in the initiation of venous thrombi.10 There is persistent histological evidence that indicates venous thrombi begin as platelet aggregates.H Myocardial infarction and stroke are... 

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