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Query: UMLS:C0151744 (myocardial ischemia)
 31,282 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent epidemiologic studies found that there is a strong association of hemostatic factors with ischemic heart disease. The Atherosclerosis Risk in Communities (ARIC) Intraindividual Variability (IIV) Study was conducted to estimate the various components of variation in hemostasis factors measured in the ARIC Study and to estimate the measures of repeatability of these factors. A total of 39 subjects (16 men, 23 women) were studied. Each had blood collected three times, with a 1- to 2-week interval between each visit. The contributions of between-person variability, within-person (biologic) variability, and processing and assay variability were estimated. Then the reliability coefficient R was estimated as the proportion of total variance accounted for by between-person variance. The reliability coefficient can be interpreted as the correlation between measures made at repeat visits. Among the various analytes, the reliability coefficients were quite high for activated partial thromboplastin time and plasma factor VIII (R = 0.92, 0.86, respectively). Low repeatability was obtained for antithrombin III activity and protein C (R = 0.42, 0.56, respectively). The lack of repeatability for these variables derives mostly from the processing (field center and laboratory) variation. Other analytes--fibrinogen, plasma factor VII, and von Willebrand factor--were intermediate in repeatability. In comparing the analyte-specific high-level to low-level groups, no substantial difference of within-person plus method coefficient of variation between the two groups was found for any analyte except for factor VIII, whereas the corresponding variance components for most analytes were higher for the higher analyte level. Reliability coefficients from this ARIC IIV study are generally higher than those found in other studies, and this is related to the relative variations in populations studied and to the time between measurements.
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PMID:Short-term intraindividual variability in hemostasis factors. The ARIC Study. Atherosclerosis Risk in Communities Intraindividual Variability Study. 134 24

The functional morphology of the endothelial cells (ECs) covering advanced but uncomplicated sclerotic plaques in humans was studied in carotid endarterectomy specimens and in coronary arteries from hearts explanted because of advanced ischemic heart disease. The endothelial layer was nearly always intact, and the endothelial patterns reflected the anticipated local flow patterns along the narrowed arteries, with the majority of flow irregularities downstream from the stenosis. Large (giant) ECs (defined as ECs with a surface area of greater than or equal to 800 microns 2) were frequently found on the plaque surface, probably indicating accelerated EC senescence attributable to sustained nondenuding injury in the region of disturbed flow. Ultrastructurally, activation of ECs with hyperplasia of organelles was frequent. In addition, as a sign of immunological activation, about 5% of ECs express class II antigens (HLA-DR and rarely focal HLA-DQ), as demonstrated by double immunofluorescence with von Willebrand factor to identify the ECs. EC activation may be responsible for adherence to the intact luminal surface by activated platelets and monocytes, which were always present (in contrast with nonsclerotic artery segments). Furthermore, an increase in myo-endothelial contacts to subendothelial modified smooth muscle cells was a regular feature of the sclerotic lesions; this feature represents an unknown process of EC and smooth muscle cell interaction in the sclerotic lesion and may be a compensatory process for EC control of smooth muscle cell proliferation. In advanced plaques the ECs are altered without denudation but with changed properties, which may contribute to plaque growth and which are consistent with the postulated EC dysfunction in the pathogenesis of arteriosclerotic lesions.
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PMID:The endothelium of advanced arteriosclerotic plaques in humans. 165 31

Patients with unstable angina pectoris (UAP; n = 20) and acute myocardial infarction (AMI; n = 34) were studied in the acute phase of ischaemic heart disease. We found significantly higher levels of thrombin-antithrombin-III (TAT) complexes, lower levels of systemic tissue plasminogen activator (t-PA) activity, and higher levels of plasminogen activator inhibitor (PAI) activity in the AMI patients compared to the UAP patients. In contrast to these specific changes, general acute phase reactants such as C-reactive protein, fibrinogen and von Willebrand factor did not differ significantly between the two groups. Studies of the relationship between coagulation (TAT-complexes) and fibrinolysis data revealed a significant positive correlation between plasma antigen concentrations of TAT-complexes and t-PA (P less than 0.02), and between TAT-complexes and PAI-I (P less than 0.002). These observations indicate a common pathophysiological mechanism underlying the changes in coagulation and fibrinolysis, suggesting that coagulation activity and t-PA-related fibrinolysis are interrelated processes in vivo, and probably take place at the level of the endothelial cell.
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PMID:Interrelationship between coagulant activity and tissue-type plasminogen activator (t-PA) system in acute ischaemic heart disease. Possible role of the endothelium. 170 58

The present study addresses the potential effects of pacing-induced myocardial ischemia on the secretion of coagulant and fibrinolytic factors within the coronary circulation. In 6 patients undergoing programmed ventricular stimulation with repeated induction of clinical ventricular tachycardia, the coronary release of tissue-type plasminogen activator (t-PA) antigen, plasminogen activator inhibitor (PAI) capacity, von Willebrand factor antigen (WF:Ag), and prostacyclin (6-keto-PGF 1a) was measured. Blood samples were collected simultaneously from the ascending aorta and the coronary sinus at baseline and immediately after the induction of ventricular tachycardia. The occurrence of pacing-induced myocardial ischemia was established by myocardial net lactate production. Myocardial ischemia was induced in every patient by repeated pacing trials. Pacing-induced ischemia did not affect the coronary release of any of the above factors. Consequently, there was no alteration of transcardiac gradients of thrombin-antithrombin complexes and D-dimer. The present results indicate that pacing-induced myocardial ischemia does not affect the release of coagulant and fibrinolytic endothelial factors or prostacyclin into the coronary circulation.
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PMID:Pacing-induced myocardial ischemia does not affect the endothelial release of coagulant and fibrinolytic factors into the coronary circulation. 170 56

Haemostatic changes may explain the paradoxical observations that regular exercise helps to prevent ischaemic heart disease but the risk of myocardial infarction and sudden death is actually increased during exercise. This study measured relevant haemostatic variables in 100 athletes before and after races of 10-26.2 miles duration and compared resting levels in athletes with 25 non-exercising controls. Prothrombin time, kaolin cephalin clotting time, fibrinogen, factor VII, factor VIII clotting (one and two stage), von Willebrand factor antigen, euglobulin clot lysis time, fibrin degradation products, full blood count, mean platelet volume, and platelet aggregation to collagen, adrenalin and adenosine diphosphate were measured. The immediate post-race results showed the familiar rise in platelet count and factor VIII clotting but there was no evidence of consumption or thrombin modification of factor VIII clotting. Platelet aggregation to adrenalin was reduced after the race and fibrinolysis was increased (P less than 0.05). The athletes at rest showed no significant differences from controls in their coagulation factor levels but showed increased fibrinolytic activity and reduced platelet aggregation to adrenalin (P less than 0.05). These results suggest a hypocoagulable rather than a hypercoagulable state during running and are consistent with the epidemiological evidence that such exercise is beneficial in the prevention of ischaemic heart disease.
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PMID:Haemostatic changes in long-distance runners and their relevance to the prevention of ischaemic heart disease. 189 55

Atherosclerotic plaques are either concentric, producing a fixed degree of obstruction, or eccentric, with retention of an arc of normal vessel wall that allows changes in medial muscle tone to vary the degree of stenosis. Plaques may also either be solid and fibrous or may contain, in addition to fibrous thickening, a pool of extracellular cholesterol. Most subjects with ischemic heart disease have mixtures of all plaque types. The endothelium over established human plaques often shows focal denudation injury, with adhesion of a platelet monolayer not detectable by angiography. Larger thrombi are due either to superficial intimal injury, which is the progression of the endothelial denudation seen over otherwise static and intact plaques, or to deep intimal injury caused by plaque fissuring (rupture). Both forms of intimal injury expose collagen and von Willebrand factor to platelets. In deep injury, tears extend from the lumen into the depths of the intima and often enter a lipid pool; in consequence, thrombus initially forms within the plaque, thereby altering its configuration and expanding its volume. Many fissures will reseal at this stage, but the plaque is larger, and the process is an important cause of episodic sudden plaque growth. A proportion of plaque fissures are associated with the additional formation of a luminal thrombus, which may be either mural or occlusive. In life, transitions between mural and occlusive thrombi and vice versa occur rapidly and frequently. Mural thrombus is associated with distal embolization of platelet masses and, in some cases, is associated with cholesterol from the plaque.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A macro and micro view of coronary vascular insult in ischemic heart disease. 220 63

Platelet aggregability and plasma factor VIII-related antigen (F. VIIIR:AG) level in 16 ischemic heart disease (IHD) patients were increased by isometric exercise and these changes were prevented by administration of a lipid lowering agent, simfibrate, a derivative of clofibrate. Serum total cholesterol (TC) level decreased and the high density lipoprotein-cholesterol (HDL-C)/TC ratio increased with the treatment. Another 7 hyperlipidemics were administered with simfibrate. Platelet malondialdehyde (MDA) production decreased with improvement in lipid profile. In an in vitro study, platelet aggregability and the plasma level of von Willebrand factor (vWF) and F.VIIIR:AG of normal citrated blood were increased by passing it through a glass bead column. Combining above results of the three separate studies, it would be suggested that hyperlipidemia might enhance platelet activation in vivo, which occurred through contact of platelets to atherosclerotic rough vessel surface. The anti-platelet effect of simfibrate might be mediated through its effect on arachidonic pathway in platelets.
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PMID:Influence of lipids metabolism on platelet activation in vivo. 641 24

In 20 patients with ischaemic heart disease (IHD), platelet sensitivity to ADP-aggregation, plasma von Willebrand factor (vWF) and plasma beta-thromoboglobulin (beta-TG) were measured before and after isometric exercise. Effect of dipyridamole on these determinants was studied in a crossover fashion. To assess plasma vWF level, a new simple method was employed which has the advantage of not requiring an optical aggregometer and was proved to be reproducible. No significant difference was seen in platelet sensitivity to ADP-aggregation, vWF and beta-TG among healthy controls, IHD patients on placebo and on dipyridamole at rest. After exercise, platelet sensitivity to aggregation, plasma vWF and beta-TG increased significantly in IHD patients on placebo. In healthy controls, no significant changes were seen. On dipyridamole, above changes seen in IHD patients were not seen. The results suggests that isometric exercise may induce platelet release reaction in vivo and may produce hypercoagulable state in IHD patients. These phenomena may be prevented by pretreatment with dipyridamole.
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PMID:Platelet release reaction in vivo in patients with ischaemic heart disease after isometric exercise and its prevention with dipyridamole. 696 82

Soluble adhesion molecules E-selectin, intercellular adhesion molecule (sICAM) and vascular cell adhesion molecule (sVCAM) were measured alongside von Willebrand factor (vWf) in 40 patients with peripheral vascular disease (PVD), 43 with ischaemic heart disease (IHD) and in equal numbers of age and sex matched asymptomatic controls. Increased vWf was found in patients with IHD (p = 0.0008) and in patients with PVD (p = 0.0001) relative to their respective controls but levels did not differ between the two patient groups. Raised sICAM was found in both PVD (p = 0.0003) and IHD (p = 0.0059) compared to their respective controls and was higher in PVD than in IHD (p = 0.0088). In the subjects taken as a whole, there was no correlation between vWf and sICAM. Levels of soluble E-selectin and sVCAM did not differ in patients or controls. These data suggest that soluble ICAM may be useful as an index of endothelial cell activation in clinical manifestations of atherosclerosis.
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PMID:Circulating endothelial cell/leukocyte adhesion molecules in atherosclerosis. 752 83

Clinical data on the contributory role of heart failure to thromboembolic risk does not differentiate between systolic and diastolic left ventricular dysfunction. We therefore conducted a population-controlled cross-sectional study to determine levels of plasma fibrinogen (associated with thromboembolism), fibrin D-dimer (a marker of fibrin turnover) and von Willebrand factor (a marker of endothelial dysfunction) in patients with ischaemic heart disease (a common cause of diastolic dysfunction) in whom left ventricular diastolic function was defined by echocardiography. We studied 106 patients: those with normal left ventricular function (n = 42, Group 1); those with left ventricular dysfunction but without aneurysms (n = 34, Group 2); and those with left ventricular aneurysm formation (n = 30, Group 3). Each of these groups was subdivided into those with (a) and without (b) diastolic dysfunction. Diastolic dysfunction was present in over 60% of patients, irrespective of left ventricular systolic impairment. There were no significant differences in median levels of plasma fibrinogen, fibrin D-dimer or von Willebrand factor in each group of patients with ischaemic heart disease, whether or not left ventricular diastolic dysfunction was present (Mann-Whitney test; P = N.S.). Systolic (rather than diastolic) dysfunction was the main correlate of these (analysis of variance, general linear model--ANOVA-GLM--P < 0.05) and the greatest abnormalities of fibrinogen, endothelial dysfunction and intravascular fibrin turnover were seen in patients with left ventricular aneurysms whether or not diastolic dysfunction was present. This study demonstrates that there is no evidence of a significant additional contribution to thrombotic risk (as assessed by plasma fibrinogen, von Willebrand factor and fibrin D-dimer) for patients with left ventricular diastolic dysfunction. A relationship is noted between some prothrombotic factors and Doppler indices of flow, which suggests a possible association between cardiac haemodynamics and thrombogenesis.
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PMID:Is diastolic dysfunction associated with thrombogenesis? A study of circulating markers of a prothrombotic state in patients with coronary artery disease. 755 62


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