Multiple Thrombi

Extracts of toxic isolates of M. aeruginosa or a purified peptide toxin injected into the bloodstream or the peritoneal cavity of mice elicit hepatotoxic effects (5-7,8). The fresh weight of the liver is greatly increased, and sinusoidal congestion, hemorrhage, and necrosis of the liver are observed. A lethal dose of purified toxin also induces multiple thrombi in the lungs and causes a marked reduction in the number of circulating blood platelets (6,7). 

There are several techniques available for mechanical thrombolysis. The most common is probing the thrombus with a microguidewire. This technique appears to be useful in facilitating chemical thrombolysis. Alternatively, a snare (e.g., Amplatz Goose-Neck Microsnare, Microvena, White Bear Lake, MN) can be used for multiple passes through the occlusion to disrupt the thrombus. " A snare can also be used for clot retrieval, mostly in simations in which the clot has a firm consistency or contains solid material. ... 

Embolism associated with long flights is generally due to thrombus formation in deep leg veins (deep-vein thrombosis, or DVT). The thrombus may move to the pulmonary circulation, where effects on lung function depend on the extent of the blockage produced. A massive embolus may occlude the main pulmonary artery, resulting in hypotension, shock and possibly death multiple small emboli cause little problem and are lysed by the fibrinolytic system. Sometimes surgical removal of the embolus is necessary, but in Pats/s case clot lysis was successful and she made an uneventful recovery. 

Multiple microemboli from disintegration of preexisting thrombus an5rwhere in the vascular system may endanger life these commonly originate in an enlarged left atrium, or a ventricular or aortic aneurysm. 

Atrial fibrillation with mitral valve disease has long been considered a stroke risk factor. Recurrent embolism occurs in 30-65% of patients with rheumatic mitral valve disease who have a history of a previous embolic event. Most of these recurrences (around 60%) develop within the first year. Mechanical prosthetic valves are a prime site for thrombus formation and patients with these valves require anticoagulation [7, 38]. Bacterial endocarditis can cause stroke as well as intracerebral mycotic aneurysms. Because mycotic aneurysms are inflammatory defects in the vessel wall, treatment with systemic thrombolysis or anticoagulation can lead to rupture with subsequent lobar hemorrhage. Nonbacterial, or marantic, endocarditis is also associated with multiple embolic strokes. This condition is most common in patients with mucinous carcinoma and may be associated with a low-grade disseminated intravascular coagulation. A nonbacterial endocarditis, called Libman-Sacks endocarditis, occurs in patients with systemic lupus erythematosus (SLE) [42],... 

Atrial myxoma is a rare atrial tumor that causes multiple emboli of either thrombus or myxomatous tissue. When myxomatous material is embolized from the left atrium into the brain arteries, they may cause the formation of multiple distal cerebral aneurysms with risk of hemorrhage [46]. Papillary fibroelastomas are rare benign cardiac tumors usually involving a heart valve. They are small vascular growths with marked papillary projections. They usually grow on the aortic or mitral valves. The tumor consists of fibrous tissue surrounded by an elastic membrane, which in turn is covered by endothelium. One of the most conunon clinical presentations is of transient ischemic attack or stroke [47,48]. 

An embolus to the MCA is common and can cause a catastrophic stroke. It is also amenable to rapid therapy. For these reasons, special emphasis is placed here on this stroke subtype. As discussed above, carotid stenosis and occlusion can cause stroke by artery-to-artery embolus to the MCA territory or by causing a low-flow state [17]. Distinguishing features of carotid stenosis include the common occurrence of multiple stereotypic spells of transient ipsilateral hemispheric or monocular dysfunction. In addition, in carotid stenosis multiple emboli may occur over a short period of time. In some cases of embolus to the MCA from a severely stenotic carotid, the embolus may be less well tolerated and the stroke more severe due to the lower perfusion pressure above the carotid lesion [17]. Embolus from the carotid to the MCA can also occur from the stump of a completely occluded carotid [59]. If the occlusion is hyperacute, often the absence of flow in the region fi om the carotid bulb to the distal ICA reflects coUapse of the lumen due to low pressure rather than occlusion of the entire carotid with thrombus. In these cases, it is sometimes possible to dissolve the fresh clot in the extracerebral portion of the carotid and advance a catheter to treat the intracerebral clot. This can be... 

Atherosclerosis of the parent vessel occluding the lumen of the penetrator by atherosclerotic plaque or superimposed thrombus Stenosis in the parent vessel on MRA, CTA, transcranial ultrasound, or direct angiography Large infarct that extends to the origin of the penetrator from the parent vessel. Multiple strokes in the distribution of the same parent vessel... 

Calculation of CBF requires knowledge of the AIF, which in practice is estimated from a major artery, assuming that it represents the exact and only input to the tissue voxel of interest, with neither delay nor dispersion. There are several clinical situations, however, where the AIF TDC will lag, and the tissue TDC will lag behind the AIF curve ( delay ). AIF delay can be due to extracranial causes (atrial fibrillation, severe carotid stenosis, poor left ventricular ejection fraction) or to intracranial causes (proximal intracranial obstructive thrombus with poor collaterals). Moreover, in such cases, the contrast bolus forming the AIF can spread out over multiple pathways proximal to the tissue ROI ( dispersion ). Delay and dispersion can result in grossly underestimated CBF and overestimated MTT [125,147,148]. 

Reversed segments of autologous saphenous vein can be used as appropriate conduits. Particularly in coronary revascularization, the internal mammary arteries and the radial arteries have widely been used [3]. However, autologous vessels may be insufficient for multiple or repeated bypasses and/or saphenous veins may have varicose degenerative alterations. Therefore, allograft arteries and veins as well as synthetic tubes have been developed, but they proved to be less satisfactory as conduits [4, 5] particularly, synthetic grafts with an internal diameter of 6 mm or less are prone to thrombus induction and occlusion [6]. 

Fig. 10.23a,b. Ovarian cancer recurrence. Coronal CT scans (a, b) in a patient with advanced recurrent clear cell cancer show multiple, predominantly cystic peritoneal implants throughout the abdomen and pelvis. The liver surface is compressed by surface implants (asterisk) (a, b). Multiple enlarged lymph nodes are seen in the right pelvis and root of the mesentery (b). Associated findings in this case include bilateral pleural effusion and a thrombus in the left femoral vein... 

Erosion and rupture of vulnerable atherosclerotic plaque is the cause of most acute coronary syndromes [32, 33]. Plaque mpture leads to the formation of an intracoronary thrombus, which produces an obstruction that acutely limits coronary artery blood flow, resulting in myocardial ischemia or necrosis. Multiple clinical and autopsy studies have confirmed the pathogenic role of coronary thrombus in cases of acute MI, unstable angina and sudden cardiac death [33, 34]. The lesions that harbor vulnerable plaques are often mildly stenotic on angiographic examination and, consequently, their stability cannot be assessed. The stability of atherosclerotic plaques is related to histological composition Figure 17.2. Unstable plaques typically comprise thin (<65 pm) fibrous caps infiltrated with macrophages that encapsulate lipid-rich necrotic cores with adjacent microcalcification [33, 34]. 

In a 47-year-old woman in whom a gastric varix was injected with enbucrilate -I- lipiodol, cyanoacrylate migrated into the inferior vena cava and left renal vein thrombus formation on the plug surface in the stomach caused a pulmonary embolus, which became infected with vancomycin-resistant enterococci, and she died with multiple lung abscesses [27 ]. 

Second-generation effects Fetotoxicity Heparin has been shown to cause osteopenia in adults, but to date there is no data on an association between heparin and fractures in preterm neonates. A recent report described a preterm infant who received unfractionated heparin for 3 weeks to freat an arterial thrombus. Later X-rays identified multiple fractures that were not present prior to heparin therapy, suggesting a correlation between the dose and duration of therapy and the fractures [20 ]. 

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