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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The diagnosis coronary artery disease is classically based on patient's symptoms and morphology, as analyzed by angiography. The importance of risk factors for the development of coronary atherosclerosis and disturbance of coronary vasomotion is clearly established. However, microembolization of the coronary circulation has also to be taken into account. Microembolization may occur as a single or as multiple, repetitive events, and it may induce inflammatory responses. Spontaneous microembolization may occur, when the fibrous cap of an atheroma or fibroatheroma (Stary i.v. and Va) ruptures and the lipid pool with or without additional thrombus formation is washed out of the atheroma into the microcirculation. Such events with progressive thrombus formation are known as cyclic flow variations. Plaque rupture occurs more frequently than previously assumed, i.e. in 9% of patients without known heart disease suffering a traffic accident and in 22% of patients with hypertension and diabetes. Also, in patients dying from sudden death microembolization is frequently found. Patients with stable and unstable angina show not only signs of coronary plaque rupture and thrombus formation, but also microemboli and microinfarcts, the only difference between those with stable and unstable angina being the number of events. Appreciation of microembolization may help to better understand the pathogenesis of ischemic cardiomyopathy, diabetic cardiomyopathy and acute coronary syndromes, in particular in patients with normal coronary angiograms, but plaque rupture detected by intravascular ultrasound. Also, the benefit from glycoprotein IIb/IIIa receptor antagonist is better understood, when not only the prevention of thrombus formation in the epicardial atherosclerotic plaque, but also that of microemboli is taken into account. Microembolization also occurs during PTCA, inducing elevations of troponin T and I and elevations of the ST segment in the EKG. Elevated baseline coronary blood flow velocity, as a potential consequence of reactive hyperemia in myocardium surrounding areas of microembolization, is more frequent in patients with high frequency rotablation than in patients with stenting and in patients with PTCA. The hypothesis of iafrogenic microembolization during coronary interventions is now supported by the use of aspiration and filtration devices, where particles with a size of up to 700 microns have been retrieved. In the experiment, microembolization is characterized by perfusion-contraction mismatch, as the proportionate reduction of flow and function seen with an epicardial stenosis is lost and replaced by contractile dysfunction in the absence of reduced flow. The analysis of the coronary microcirculation, in addition to that of the morphology and function of epicardial coronary arteries, and in particular appreciation of the concept of microembolization will further improve the understanding of the pathophysiology and clinical symptoms of coronary artery disease.
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PMID:Coronary microembolization--its role in acute coronary syndromes and interventions. 1060 63

The purpose of this study was to investigate the histological characteristics of atheromatous carotid plaque, and to analyze the relationship between the angiographic findings and the clinical features. We retrospectively reviewed 55 cases of carotid endarterectomy for extracranial internal carotid artery stenosis, who were treated at our institute from January 1995 to December 1997. The histological examination included hematoxylin-eosin staining, Masson-trichrome staining, and immunostaining for antismooth muscle antibody and anti-CD68 antibody. The main compositions of the carotid plaque included synthetic type vascular smooth muscle cells and extracellular matrix. The histological findings showed ulceration in 49 (89.1%) cases, calcium deposits in 42 (76.4%) cases, and an inflammatory reaction in 44 (80.0%) cases. Neurological abnormalities were strongly associated with plaque ulceration (P = 0.045) and an inflammatory reaction (P = 0.013), whereas no correlation existed regarding calcium deposits (P = 0.173). The angiographic findings showed ulceration in 46 (83.6%) cases. Plaque ulceration in the angiography findings showed no statistically significant correlation with the histologic findings (P = 0.410) and preoperative neurologic abnormalities (P = 0.059). All of the atherosclerotic risk factors such as hypertension, smoking, diabetes mellitus, hyperlipidemia, and myocardial infarction had no statistically significant correlation with the histological features of the carotid plaque. In conclusion, the main compositions of carotid plaque were synthetic-type vascular smooth muscle cells and extracellular matrix. The histological ulceration and inflammatory reaction of the plaque showed a statistically significant correlation with the preoperative neurologic symptoms, whereas no correlation was seen in the calcium deposits. Angiographic ulceration showed no correlation with the histological findings or preoperative neurologic abnormalities. In addition, the histological findings showed no correlation with the atherosclerotic risk factors.
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PMID:The relationship between the angiographic findings and the clinical features of carotid artery plaque. 1064 81

A 31-year-old parturient delivered twins at 35 weeks' gestation by cesarean section with spinal anesthesia. Following anesthesia induction, hypotension and bradycardia occurred, and were immediately treated with theodrenaline plus cafedrin (Akrinor) and atropine. Blood pressure and heart rate increased to 180/100 mmHg and 140 beats per minute, respectively. Several minutes later, the patient developed a myocardial infarction (MI) that she survived after intensive care treatment without sequelae. Although the coronary angiography showed normal coronary vessels, an intravascular ultrasound study demonstrated an atheroma in the left main coronary artery with ruptured fibrous cap. Laboratory screening for risk factors of coronary artery disease (CAD) showed hypercholesterinemia, increased factor VII activity, and hyperfibrogenemia. Angiographically normal coronary vessels are frequently found in pregnant patients who suffered MI. In these patients, coronary spasms have been discussed as the major mechanism of disease. Our case demonstrates that a significant CAD may be present despite angiographically normal findings. Plaque rupture was triggered by hypertension and led to MI as the first symptom of disease. On the basis of these findings, we believe that MI during pregnancy is more often caused by plaque rupture than may be expected, according to the current literature.
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PMID:Coronary artery plaque disruption as cause of acute myocardial infarction during cesarean section with spinal anesthesia. 1096 Feb 9

Endothelial dysfunction and changes in arterial wall morphology including thickening of the tunica intima, excess synthesis of collagenous matrix (fibroblastic intimal thickening) and permanent or dynamic deposition of lipids (fatty streaks) already occur in childhood or adolescence. Definite atherosclerotic plaques in the carotid arteries usually do not manifest themselves before menopause in women or age 40 in men. Obviously, cumulative (long-term) and excessive exposure of the vessel wall to risk factors is required to overcome highly effective defense mechanisms which have not yet been fully investigated. Initiation and early progression of atherosclerosis rely on conventional vascular risk factors such as hyperlipidemia, hypertension, smoking, severe alcohol consumption and chronic infections. Plaque extension is effectively compensated by a focal widening of the vessel, thereby preventing the development of lumen obstruction (vascular remodeling). For stenosis to emerge conventional plaques must convert to complicated plaques characterized by plaque rupture and consecutive atherothrombosis. This process usually starts with small- to medium-sized plaques. Potential determinants of plaque rupture are the composition of the lesion (large lipid-rich core), damage of the fibrous cap (destabilization by chronic inflammation) and hemodynamic stress. According to pathological observations, fissuring of atherosclerotic lesions is a frequent event, while the formation of overlying large thrombi (with progression of stenosis or vessel occlusion) is definitely rare. This conjecture emphasizes the significance of local and systemic thrombus-promoting factors. Actually, the risk profile of advanced atherogenesis in the Bruneck Study was primarily composed of markers of enhanced prothrombotic capacity, attenuated fibrinolysis and clinical conditions known to interfere with coagulation. Almost all subjects with > or =3 procoagulant risk conditions developed carotid stenosis or showed progression of preexisting stenosis during a 5-year period. Increasing insights into the complex biology of arterial atheroma and awareness of the etiologic peculiarities of advanced complicated plaques may serve as a basis for identifying high-risk subjects and for novel vascular prevention strategies with focus on plaque stabilization and antithrombotic/anticoagulant measures.
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PMID:Biology of arterial atheroma. 1109 78

Up to now 136 cases of myocardial infarction during pregnancy have been reported, and angiography revealed normal findings in 47%. In these cases coronary spasms have been discussed as the major mechanism of the disease. In isolated cases coronary artery dissection may also present with a normal coronary angiography. The case of a 31-year-old pregnant women who developed myocardial infarction during a caesarean section under spinal anaesthesia gives rise to the assumption that an early stage of coronary artery disease may be the third cause that has to be considered. Probably as a consequence of phases of tachycardia and hypertension during the course of anaesthesia, the patient developed a myocardial infarction that she survived without sequelae. While coronary angiography showed normal coronary vessels, an intravascular ultrasound study (IVUS) demonstrated an atheroma in the left main coronary artery with a ruptured fibrous cap. Laboratory screening for risk factors of coronary artery disease (CAD) showed hypercholesterinemia, increased factor VII activity and hyperfibrinogenemia. Platelet aggregation was not inhibited by acetylsalicylic acid. It was pointed out recently that even in asymptomatic patients, plaques may be present in coronary vessels indicating an early stage of CAD that cannot be diagnosed by angiography. Plaque rupture is often triggered by hypertension and may lead to myocardial infarction, instable angina pectoris, or sudden ischemic death. As IVUS is a new diagnostic tool that allows diagnoses of even early stages of CAD we believe that myocardial infarction during pregnancy is more often caused by plaque rupture than may be expected according to the current literature.
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PMID:[Myocardial infarction during pregnancy]. 1135 26

The past decade has witnessed enormous progress in our understanding of the nature of this process. The development of an atherosclerotic plaque is a complex process which begins with endothelial dysfunction, the trigger for which are factors such as hypercholesterolemia, smoking, hypertension, hyperhomocysteinemia and impaired glucose metabolism. This dysfunction includes increased endothelial permeability to lipoproteins and other plasma constituents, which is mediated by NO, PDGF, prostacyclin, angiotensin II and endothelin; up-regulation of endothelial adhesion molecules including VCAM-1, ICAM-1, and selectins and migration of leukocytes and monocytes-macrophages in the subendothelial space mediated by oxidized LDL, MCP-1, PDGF and MCSF. The next step includes smooth-muscle cells migration (stimulated by PDGF and TGF-beta), T-cell activation (mediated by TNF-alpha and IL-2), formation of foam-cells from macrophages (mediated by oxidized LDL, MCSF, TNF-alpha and IL-1) and platelet adherence and aggregation (stimulated by thromboxane A2, tissue factor etc). The smooth muscle cells form a fibrous cap which confers mechanical stability of the plaque and separates the lipid rich thrombogenic core from the lumen and circulating blood. Whether a plaque will remain intact and therefore stable or rupture and lead to thrombosis causing an acute coronary syndrome (MI, unstable angina pectoris) depends upon a number of factors, the most important of which is its composition. Plaque size plays only a minor role in determining risk of an acute coronary syndrome. Rupture of the fibrous cap occurs due to thinning of the cap caused by an influx and activation of macrophages which release metalloproteinases and other proteolytic enzymes (stimulated by inflammatory cells, particularly T-lymphocytes). These enzymes cause degradation of the fibrous tissue of the cap which can result in thrombous formation and occlusion of the artery. Stable plaques have a thick fibrous cap, a small lipid core, and few inflammatory cells. In contrast, vulnerable plaques have a high lipid content, numerous inflammatory cells, and a thin fibrous cap with reduced collagen and vascular smooth muscle cells in it. Although vulnerable plaques are believed to account for only a small number of all coronary atheromas, they are responsible for most acute coronary events.
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PMID:[New information on the pathophysiology of atherosclerosis]. 1137 94

Hemodialysis patients frequently show associated hypertension, which can lead to a number of cardiovascular complications. The aim of this study was to assess the effects of hypertension on the structure and function of the carotid artery and left ventricle (LV) in hemodialysis patients. In addition, we investigated the contribution of hemodialysis and other risk factors. Fifty-two hemodialysis patients, 71 hypertensive patients (HT group) and 30 normotensive subjects (NT group) were included in this study. Hemodialysis patients were divided into two groups: 35 patients with hypertension (HDHT group), and 17 patients without hypertension (HDNT group). We measured intima-media thickness (IMT), plaque score, end-diastolic diameter, and stiffness index beta of the carotid artery by ultrasonography, and LV mass index (LVMi), endocardial fractional shortening (FS), and midwall FS (MWS) by echocardiography. A multiple stepwise regression analysis including hemodialysis, hypertension, diabetes mellitus, and other risk factors was also performed. IMT was significantly higher in the HT and HDHT groups than in the NT group. Plaque score and diameter of the carotid artery were higher in the HDHT group than in the other three groups. The stiffness index beta was higher in the HDHT group than in the non-hemodialysis groups. In multivariate analysis, IMT was independently correlated with age and hypertension. Plaque score and stiffness index beta were independently associated with age, hypertension, and hemodialysis. LVMi was higher in HT and hemodialysis-patients groups than in the NT group. Hypertension and hemodialysis were strong and independent predictors of LVMi. FS showed no significant differences among the four groups, but MWS was significantly lower among the hemodialysis patients than in the NT group. MWS was independently correlated with hemodialysis and diabetes. In conclusion, hemodialysis per se advanced both atherosclerosis and arteriosclerosis of the carotid artery. Moreover, it increased LVMi and caused cardiac dysfunction. Associated hypertension might thus accelerate the progression of atherosclerosis and arteriosclerosis of the carotid artery and the increase of LVMi.
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PMID:Structure and function of the left ventricle and carotid artery in hemodialysis patients. 1140 44

The objective of this study was to elucidate the association between the polymorphism of stromelysin-1, also called matrix metalloproteinases-3 (MMP-3), and smoking in the pathogenesis of young acute myocardial infarction (MI). Plaque rupture is well established as a critical factor in the pathogenesis of acute MI. MMP-3 can degrade extracellular matrix and are identified extensively in human coronary atheroslcerotic plaques, and may contribute to the weakening of the cap and subsequent rupture. We studied 150 consecutive patients with acute MI onset at age under 45 years (84% men) and 150 sex- and age-matched control subjects. 5A/6A genotype in the stromelysin-1 promoter was determined using polymerase chain reaction and direct sequencing. Results show that the frequency of the 5A allele and the prevalence of 5A/5A + 5A/6A genotypes were both significantly higher in the young MI than the control group (35.0% vs. 20.0%, odds ratio [OR] 2.15, 95% confidence interval [CI] 1.30 to 6.80, p<0.001; 44.7% vs. 27.4%, OR 2.19, 95% CI 1.21 to 3.98, p=0.009). Multiple logistic regression analysis showed that the 5A allele was an independent risk factor (OR 2.36, 95% CI 1.24 to 5.90, p=0.008) as were as smoking (OR 3.92, 95% CI 1.75 to 9.21, p=0.001), diabetes mellitus (OR 3.51, 95% CI 1.41 to 6.32, p=0.0068) and hypertension (OR 1.85, 95% CI 1.35 to 4.33, p=0.0025) for the premature onset of MI. Compared to 6A/6A subjects, among patients who did not smoke, the 5A allele polymorphism was associated with a higher risk of MI at a young age (OR 2.69, 95% CI 1.3 to 8.6), but smoking carriers of the 5A allele had a significantly 10-fold higher risk of MI (OR 9.98, 95% CI 2.3 to 12.5). We can conclude that there was a significant association between the 5A/6A polymorphism in the promoter region of stromelysin-1 gene and young MI in Taiwan. A synergistic effect between smoking and this polymorphism for the premature onset of MI had been shown in this study.
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PMID:Synergistic effect of stromelysin-1 (matrix metallo-proteinase-3) promoter 5A/6A polymorphism with smoking on the onset of young acute myocardial infarction. 1287 19

Previous studies have suggested that the Gly460Trp polymorphism of the alpha-adducin gene (ADD-1) is associated with salt sensitivity and primary hypertension. The results of linkage or association studies of ADD-1 of different populations are controversial. This study investigated the relationship between the Gly460Trp polymorphism of ADD-1 and essential hypertension in a Korean population. The subjects (n=903) were participants in a population-based study in Jangseong County, Korea. The Gly460Trp polymorphism of ADD-1 was determined using a polymerase chain reaction method. The frequency of the 460Trp allele was 59.4% in normotensives and 61.1% in hypertensives (p=0.523). The frequencies of the genotypes did not differ significantly between the hypertensive and normotensive groups (16.3% Gly/Gly, 45.8% Gly/Trp, and 38.0% Trp/Trp in normotensives; 16.2% Gly/Gly, 45.8% Gly/Trp, and 38.0% Trp/Trp in hypertensives; p=0.928). After adjusting for other risk factors, Gly/Trp and Trp/Trp were not associated with hypertension (OR 1.00, 95% CI 0.65-1.53, Gly/Trp vs. Gly/Gly; OR 1.22, 95% CI 0.79-1.90, Trp/Trp vs. Gly/Gly). These findings suggest that the Gly460Trp polymorphism of ADD-1 is not associated with hypertension.
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PMID:Alpha-adducin Gly460Trp polymorphism and essential hypertension in Korea. 1560 90

The purpose of this study was to determine the relationship between organic changes in carotid artery walls and candidate gene polymorphism in Japanese sufferers of essential hypertension. Carotid Ultrasonography was used to measure intima-media thickness (IMT) and presence of plaque formation. Patients were divided into two groups; a hypertension (HT) group and a healthy control (C). Group HT consisted of 273 subjects (56.5 +/- 11.3y) and group C consisted of 500 subjects (55.6 +/- 11.4y). 5HTR2A (T102C, A-1438G) and beta3-AR (Trp64Arg) genetic polymorphism for genetic analysis were performed on 43 subjects (63.5 +/- 8.5y) in group HT and 24 subjects (60.3 +/- 6.8y) in group C. IMT showed 0.81 +/- 0.28mm in Group C and 1.05 +/- 0.22mm in Group HT in patients aged 50 or above, respectively. The thickening was significantly greater in Group HT than in Group C (p < 0.01). Plaque was present in 45.1% in Group C and 70.2% in Group HT in patients aged 50 or above, respectively. It was significantly present greater in Group HT than in Group C (p < 0.01). Results of genetic analysis showed no difference between Group HT and Group C for either genotype of allele frequency of T102C and A-1438G, or of beta3-AR. It is suggested that increase of IMT and formation of plaque are risk factors in patients aged 50 or above with hypertension, and that careful observation of the carotid artery will be effective for early detection of arteriosclerosis, and to predict the symptoms thereof.
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PMID:[Relationship between of carotid ultrasonography in Japanese hypertensive subjects for intima-media thickness and plaque, and candidate gene polymorphism--possibility of early detection of arteriosclerotic disease]. 1591 64


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