Occlusion zones

Occlusion zones 29 Octahedral geometry 311 Octopus, intelligence of 24 Oils, composition of 380 Okadaic acid 545 Old yellow enzyme 783 Oleate hydratase 526, 688 Oleic acid 381 Olfactory responses 558 Oligomer(s)... 

Presence or absence of thrombus Distal landing zone diameter and length Iliac arteries presence of aneurysms and occlusive disease Access arteries (common, external and femoral arteries) Diameter, presence of occlusive disease Contraindications for EVAR Short proximal neck... 

Several disease states can result from abnormal blood clots. For example, strokes were mentioned previously. However, the most common and deadliest thrombotic disease is myocardial infarction (MI). Atherosclerosis has long been associated with reduced cardiac function and elevated mortality due to rupture of atherosclerotic plaques. The rupture of an atherosclerotic plaque usually results not only in blockage due to the plaque itself but also in the immediate formation of an occlusive blood clot, which results in an MI. Immediately after the initiation of an MI, a zone of necrosis begins to develop around the area as ischemia proceeds. It is during this early phase of ischemia (several hours) that therapeutic intervention not only can be life-saving but also can minimize the amount of necrotic heart tissue formed. 

Of greater therapeutic relevance is the zone lying peripheral to the region of dense ischemia and perfused at somewhat higher CBF levels the ischemic penumbra. In baboons subjected to MCA occlusion, CBF was measured along with the extracellular potassium concentration and sensory evoked poten-... 

Szabo et al. (2001) 102 >50 or occlusion Territorial stroke (n=30) Subcortical stroke ( =13) Territorial infarction with fragmentation (n=ll) Disseminated small lesions (n=15) Borderzone lesions (n=33) The degree of ICA stenosis may favor certain stroke patterns. In patients with high-grade stenosis the highest frequency of lesions occurs in the hemodynamic risk zones... 

Myocardial infarction (MI) is caused by the acute thrombotic occlusion of a coronary artery. The myocardial region that has been cut off from its blood supply dies within a short time owing to the lack of 02 and glucose. The loss in functional muscle tissue results in reduced cardiac performance. In the infarct border zone, spontaneous pacemaker potentials may develop, leading to fatal ventricular fibrillation. The patient experiences severe pain, a feeling of annihilation, and fear of dying. 

Low flow may occur secondary to systemic hypotension, as during cardiac arrest. This results in bilateral infarcts, usually in the posterior boundary zones, and causes cortical blindness, visual disorientation and agnosia, and amnesia. Alternatively, a relatively small fall in systemic blood pressure in the presence of internal carotid occlusion or stenosis may cause unilateral boundary zone infarction, usually in the anterior and subcortical regions. This causes contralateral weakness of the leg more than the arm, with sparing of the face. 

Alcoholic hepatitis also leads to a postsinusoidal block following the deposition of alcoholic hyaline in the centrilobular zone, with perivenous fibrosis and subsequent occlusion of the small veins. 

Reocclude the coronary artery, and infuse approximately 3 mL of 1 3 diluted USB via the atrial catheter to demarcate the occlusion-induced ischemic zone (USB stains the normoxic tissue, whereas the ischemic zone termed the area at risk remains unstained). 

Both acute coronary syndromes (ACSs) and infarcts in chronic phase affect, as a result of the occlusion of the corresponding coronary artery, one part of the two zones into which the heart can be divided (Figure 1.14A) (1) the inferolateral zone, which encompasses all the inferior wall, a portion of the inferior part of the septum and most of the lateral wall (occlusion of the RCA or the LCX) (2) the anteroseptal zone, which comprises the anterior wall, the anterior part of the septum and often a great part of inferior septum and part of the mid-lower anterior portion of lateral wall (occlusion of the LAD). In general, the LAD, if it is large, as is seen in over 80% of cases, tends to perfuse not only the apex but also part of the inferior wall (Figures 1.1 and 1.14). 

In the classical ECG assessment of an STE-ACS, the leads with electrocardiographic changes give to us an approximate diagnosis of the location of the injury (anteroseptal vs inferolateral zone). However not much information was given regarding what the occluded artery was, where the occlusion was located and how large the area at risk was. Therefore, for example, the classical interpretation of... 

Figure 4.17 Acute myocardial infarction with ST-segment elevation in II, III and VF and ST-segment depression in V1-V3. This pattern corresponds classically to an infarction involving inferior and posterior walls. Nowadays, this is the pattern of STE-ACS of inferolateral zone evolving to inferolateral infarction due to distal occlusion of a dominant RCA (ST-segment depression in I and V1-V3,...

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