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

Present-time Greenlanders are living a stressful 'westernized life' complete with an elevated consumption of tobacco and alcohol. The drinking water in Greenland is extremely soft and the diet is very low in calcium (and probably magnesium) and rich in carbohydrate and fat. Despite these different predisposing factors, death from ischemic heart disease is 3-6 times less frequent than in Denmark. The serum calcium/magnesium ratio in Greenlanders is significantly lower than in Danes. Magnesium deficits in patients with acute myocardial infarction, as well as epidemiologically positive correlations between dietary calcium/magnesium ratios and ischemic heart death, are the basis for attributing the low incidence of ischemic heart death in Greenland to the low Greenlandic calcium/magnesium ratio in diet and blood serum. Other characteristics of the Greenlandic disease pattern include a low incidence of stones in kidney and urinary tract, few cases of diabetes mellitus, prolonged bleeding time, increased atrioventricular block and osteoporosis, all of which may also be related to a low calcium and high magnesium metabolic status.
Magnesium 1987
PMID:Greenland, a soft-water area with a low incidence of ischemic heart death. 344 6

Mortality rates for acute myocardial infarction and ischaemic heart disease (IHD) of white males and females in South Africa are much higher than those in the USA, Australia, England and Wales when individuals in the 15- to 64-year age group are considered. Magnesium levels in the drinking water of 12 South African districts and deaths due to IHD assessed on the basis of corrected statistics for deaths apparently due to IHD in white residents were studied and a significant negative correlation was found between these two variables. No such correlation has been demonstrated in blacks.
Magnesium 1986
PMID:Content of magnesium in drinking water and deaths from ischaemic heart disease in white South Africans. 372 39

Previous work has demonstrated that myocardial ischemia results in a breakdown of the excitation-contraction coupling system of cardiac muscle associated with lysosomal activation. It has been hypothesized that lysosomal activation during the course of myocardial ischemia is mediated by the production of oxygen free radicals. We have tested the hypothesis that myocardial ischemia results in the activation of lysosomal phospholipase C and disruption of calcium transport in sarcoplasmic reticulum (SR) mediated by oxygen free radicals. Three groups of dogs were studied: sham-operated controls (n = 6); normothermic global ischemia of 30-min duration (n = 6); and 30 min of normothermic global ischemia pretreated with intracoronary superoxide dismutase (SOD, 10 micrograms/ml) plus catalase (25 micrograms/ml). In vitro, isolated SR demonstrated a significant depression of calcium uptake rates and Ca2+-stimulated, Mg2+-dependent ATPase activity at both pH 7.0 and 6.4 with the depression at pH 6.4 greater than 7.0. This depression of SR function was significantly inhibited in hearts pretreated with SOD plus catalase. In sham-operated controls, acid-induced dysfunction was associated with substantial loss of phospholipid phosphorus and major changes in phospholipid composition. SR contained an extremely active, ion-independent sphingomyelinase-phospholipase C (SM-PLC) that had maximal activity at pH 4.5-5.0. This SM-PLC was activated when control SR was incubated at acid pH and the specific activity of SM-PLC was decreased 50% in SR isolated from normothermic global ischemia. Activity remained at control levels in hearts pretreated with SOD plus catalase.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sarcoplasmic reticulum dysfunction: phospholipid alterations induced by lysosomal phospholipase C. 377 91

Until relatively recently, it was generally believed that hypomagnesemia was a rare entity in clinical practice. It is clear, however, from newer studies that the overall incidence of hypomagnesemia in hospitalized patients can range from 7 to 52%. The greatest association of hypomagnesemia in hospitalized patients appears to be in hypokalemic states and in patients confined to intensive care units. Most of these patients demonstrate cardiovascular abnormalities, ranging from cardiac arrhythmias and atrial fibrillation to hypertension. On the basis of primarily epidemiologic and experimental findings, it has been suggested that there may be a strong association between the dietary intake of Mg (and errors in the Mg metabolism and distribution of Mg in the body), the concentration of this element in the myocardium and blood vessels, and the risk for development of cardiac arrhythmias, sudden death ischemic heart disease, hypertension, transient ischemic attacks, strokes and pre-eclampsia-eclampsia. During the past 5-6 years, a considerable amount of new, quantitative clinical evidence has been found which lends considerable support to these tenets. Clinical trials utilizing Mg as a therapeutic tool to treat refractory arrhythmias, digitalis toxicity-associated arrhythmias, myocardial infarctions, diabetic angiopathy, transient ischemic attacks, cerebral resuscitation, hypertension and 'classical' migraine are under way, and to an extent have been successful. Careful assessment of serum, blood cells, and urine for free versus bound Mg should be done routinely in cardiovascular disease and high-risk patients.
Magnesium 1985
PMID:New perspectives on the role of magnesium in the pathophysiology of the cardiovascular system. I. Clinical aspects. 391 80

The case report demonstrates another case of hypomagnesemia with electrocardiographic evidence of acute myocardial ischemia due to coronary spasm. The patient was successfully treated with intravenous, followed by oral, magnesium sulfate. Magnesium therapy may be justified especially in patients with prolonged QT intervals, cardiac arrhythmias and hypokalemia with hypomagnesemia.
Magnesium 1986
PMID:Clinical hypomagnesemia, coronary spasm and cardiac arrhythmia. 395 98

Dietary Mg deficiency is thought to promote coronary artery spasm, probably through Ca overloading of vascular smooth muscle (VSM) cells. We now report the demonstration of a coronary arteriopathy in hamsters fed a Mg-deficient diet for 10 days or more. Affected arteries showed endothelial and VSM cell hyperplasia and pleomorphism, chronic inflammation of the media and adventitia, and fibrinoid necrosis. Lesions of myocardial ischemia, distinct from the well-known lesions of myocardial necrosis and calcification common in Mg deficient animals, were also present. Von Kossa positive granules were found in the VSM of Mg-deficient, but not control, hamsters. This vasculopathy is a new factor to be considered in the pathophysiology of Mg deficiency. It is consistent with the view that Ca loading of VSM plays an important role in this condition and could be related to the occurrence of coronary artery spasm.
Magnesium 1985
PMID:Coronary arterial lesions in Mg-deficient hamsters. 404 48

The incidence of death from ischaemic heart disease (IHD) and acute cardiac arrhythmias is increased in some regions where magnesium levels are reduced in soil and water. Magnesium levels in the drinking water of twelve South African magisterial districts have been evaluated together with corrected statistics for deaths apparently due to IHD in White males from the same districts. A significant negative correlation was found between the incidence of deaths ascribed to IHD and the magnesium content of drinking water. Future, prospective, multivariate studies are required to elucidate whether magnesium scarcity in a geological environment is a major coronary risk factor.
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PMID:Magnesium and deaths ascribed to ischaemic heart disease in South Africa. A preliminary report. 663 65

We examined sera from 159 patients with ischemic heart disease and hypertension and from 50 apparently healthy control subjects for content of trace elements, cholesterol, triglyceride, and enzymes. Concentrations of copper, cobalt, cholesterol, and triglyceride were increased in all patients, but calcium was decreased in patients with hypertension, acute myocardial ischemia, and acute myocardial infarction. Also accompanying acute myocardial infarction were decreased concentrations of zinc and iron but increases in nickel, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. Magnesium concentration was lower in patients with acute myocardial ischemia. In acute myocardial infarction, the concentrations of copper, zinc, and iron were higher after 21-30 h (as compared with the values at 0-10 h), by which time concentrations of calcium, magnesium, cobalt, and alanine aminotransferase had decreased. The variation in concentration of trace elements in serum from cases of ischemic heart disease and hypertension corresponds to the severity of the disorder.
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PMID:Trace elements in serum from Pakistani patients with acute and chronic ischemic heart disease and hypertension. 671 25

1 The hypothesis that magnesium deficiency, linked to the magnesium content of drinking water, induces major tone increases in coronary arteries and enhances their responses to vasoactive agents to an extent sufficient to explain sudden death associated with ischaemic heart disease was examined in an in vitro preparation. 2 The spontaneous tone of cattle coronary arteries was not increased during a 30 min exposure to Mg2+-deficient Krebs until the mineral was omitted entirely from the bathing medium, and even then the observed increase was small. Only in strips maintained under extremely deficient conditions for a prolonged period, namely Mg2+ concentration of 0.2 mM and 0.0 mM for 3 h, was tone substantially greater than in controls in standard (1.2 mM) Mg2+-Krebs. 3 Responses to acetylcholine and to noradrenaline were not increased in Mg2+-free Krebs but those to potassium and to 5-hydroxytryptamine were enlarged over the lower parts of their concentration-response curves. Responses to potassium and to 5-hydroxytryptamine were also examined in Krebs containing very low concentration of Mg2+ (0.4 and 0.2 mM) and only modest increases in contraction size were detected. Increases in the Mg2+ concentration of the Krebs (to 4.8 mM) depressed responses to potassium and 5-hydroxytryptamine. 4 It is concluded that Mg2+ deficiency must be nearly complete (0.4-0.0 mM) to induce even moderate tone increases in coronary vessels, or to sensitize them to agonist responses, and that there is no reason to link marginally subnormal Mg2+ levels, occasionally reported in humans with heart disease, to marked changes in coronary dynamics.
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PMID:The effect of magnesium deficiency and excess on bovine coronary artery tone and responses to agonists. 685 Jan 65

Magnesium ions are important for maintaining the functional and structural integrity of the myocardium. Epidemiologic studies suggest that myocardial hypomagnecytia can predispose to sudden cardiac death and that hard water protective factor preventing heart attack could be magnesium. Recent studies show that infarcted portion of the myocardium has lowered magnesium content as compared to noninfarcted segment. Magnesium deficiency sensitises the myocardium to the toxic effect of various drugs, hypoxia etc. and magnesium administration is protective. The metabolic, biochemical and electrophysiologic effects of magnesium appear to be significant in treatment of myocardial ischaemia. Magnesium is a metal-coenzyme and activates adenosine-triphosphatase which may be inhibited by nonglucose fuels like lactate and free fatty acids. Magnesium deficiency may be responsible for the chronic electrical instability of the myocardium predisposing to sudden cardiac death. The acute precipitating stress dependent trigger which lie in the brain may also be related to magnesium. In addition to fast Na and Ca channels there could be a Mg-carrying transport system maintaining the electrical activity of the myocardium. There is sufficient evidence to suggest the use of magnesium salts against ischaemic heart disease and sudden cardiac death. Magnesium is cardioprotective and influences action potential duration, membrane potential and perhaps maintains the fast response. The therapeutic and prophylactic value of magnesium needs further assessment.
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PMID:Magnesium in atherosclerotic cardiovascular disease and sudden death. 697 57


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