Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0151744 (myocardial ischemia)
 31,282 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Magnesium deficiency may result from reduced dietary intake of the ion or increased losses in sweat, urine or faeces. Stress potentiates magnesium deficiency, and an increased incidence of sudden death associated with ischaemic heart disease is found in some areas in which soil and drinking water lack magnesium. Furthermore, it has been demonstrated experimentally that reduction of the plasma magnesium level is associated with arterial spasm. Careful studies are required to assess the clinical importance of magnesium and the benefits of magnesium supplementation in man.
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PMID:Magnesium and sudden death. 635 22

Intravenous injections of ionic contrast media are widely used in the performance of radiographic techniques. The effects of ionic contrast media on lung water are unclear in the setting of elevated left atrial pressure, particularly in the presence of myocardial ischemia. In this study, we examined the effects of bolus injections of intravenous sodium meglumine diatrizoate (Renografin 76, 1 ml/kg, injected at 20 ml per second) on measures of extravascular lung water (EVLW) at several levels of left atrial pressure and in the presence of myocardial ischemia. Bolus injections of Renografin 76 produced significant increases in EVLW, with similar mean peak increases of approximately 26% EVLW at low (initial pressure less than 3 mm Hg), moderate (approximately 15 mm Hg), and elevated left atrial pressures (approximately 25 mm Hg). At matched pressures, the peak change in EVLW in the ischemic dogs was +45%, +60%, and +70%, respectively (all P less than .001 vs. the nonischemic dogs). Thus, use of intravenous ionic media precipitated acute transient increases in lung water, which were exaggerated by myocardial ischemia. While the effects were time limited in this experimental model, caution is advised in using intravenous ionic media in patients who have left ventricular dysfunction, particularly if underlying ischemia is present.
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PMID:Extravascular lung water: effects of using ionic contrast media at varying levels of left atrial pressure and during myocardial ischemia. 333 Jun 19

The present study was undertaken to determine whether diminished coronary blood flow without abrupt reperfusion results in myocardial cell swelling and, if so, whether the increment in tissue water is related to an increase in coronary vascular resistance. In 19 anesthetized open-chest dogs on right heart bypass with controlled coronary perfusion a decrease in coronary flow resulted in an increase in intracellular water and a progressive increase in coronary resistance. In 15 additional dogs, 180 min of ischemia produced by partially occluding the circumflex coronary artery resulted in significant increases in myocardial water content and progressive decreases in regional myocardial blood flow (microsphere technique). A significant correlation was found between the progressive decreases in myocardial flow and the increases in myocardial water (r = -0.82, P less than 0.001). In five experiments, hypertonic mannitol prevented water accumulation and progressive decreases in blood flow in the ischemic tissue. Thus myocardial ischemia produced by a decrease in antegrade coronary perfusion results in myocardial cell swelling and an associated progressive perfusion deficit.
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PMID:Myocardial cell volume and coronary resistance during diminished coronary perfusion. 643 26

Ischaemic heart disease (IHD) is a major public health problem in most industrialised countries. In the death rates from IHD, marked differences exist between various countries and also between different areas of individual countries. Unfavourable dietary factors appear to play an important role in the aetiology of IHD, and thus differences in dietary habits and the quality of food may be mainly responsible for the geographic differences in the prevalence of IHD. The present liberal use of salt as well as the refining and other industrial processing of food increase the content of sodium and decrease the content of potassium and magnesium in the diet. The high intake of sodium and the inadequately low levels of potassium and magnesium in the diet predispose to the development of arterial hypertension. Since arterial hypertension is a major risk factor of IHD, the distorted electrolyte composition of our present diet can be considered an important aetiological factor of this disease. To decrease the body burden of sodium, diuretic agents are frequently used. Unfortunately, in the presence of the relatively low content of potassium and magnesium in the diet, the diuretic-induced increases in the excretion of these electrolytes commonly decrease the potassium and magnesium levels in the body. The falls in potassium and magnesium may increase the death rate from IHD by predisposing the heart to fatal arrhythmias, and also by other mechanisms. The likelihood of magnesium deficiency also appears to be influenced by the area of residence. The higher-than-average death rates from IHD in the so-called North Karelia area in eastern Finland and in some other areas with exceptionally high death rates from this disease may be at least partly due to the very low levels of magnesium in the soil and drinking water. It can be concluded that electrolyte disturbances have important implications in the aetiology and pathogenesis of IHD.
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PMID:Ischaemic heart disease. An epidemiological perspective with special reference to electrolytes. 649 99

Increased extravascular lung water has been reported following periods of myocardial ischemia. To determine whether increased pulmonary microvascular permeability was produced by ischemia, total protein lymph-to-plasma concentration ratios (CL/CP) were obtained at mechanically increased left atrial pressures (Pla) before and after ligation of the left anterior descending coronary artery in dogs. Pulmonary and systemic vascular pressures and cardiac output were monitored and lymph flow was measured from an afferent tracheobronchial lymphatic. Osmotic reflection coefficients (sigma) for total protein were estimated using CL/CP = 1-sigma at high filtration rates, and permeability-surface area (PSf) products were fit to the data. The postischemic lung lymph data best fit average values of sigma = 0.68 and PSf = 0.073 ml X min-1 X 100 g-1 wet weight. There were no significant differences in lymph protein or water clearances between the pre- and postischemic increased Pla states or for myocardial ischemia compared with control values for the experimental preparation. Levels of 6-ketoprostaglandin F1 alpha, a degradation product of prostacyclin, increased by 10- to 14-fold above preischemic values in pulmonary lymph, and there was a significant increase in pulmonary vascular resistance during ischemia. Extravascular lung water was not increased above that attributed to the increased Pla alone. These data indicate no significant increase in pulmonary microvascular permeability to plasma proteins during myocardial ischemia.
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PMID:Failure of myocardial ischemia to increase pulmonary microvascular permeability in dogs. 654 45

Transient myocardial ischemia in postoperative hypertension is relatively common with coronary artery bypass surgery. This study examines the effect of hypertension during reperfusion of transiently ischemic myocardium. The animal model was open chest pigs with myocardial ischemia induced by the occlusion of the left anterior descending coronary artery for 30 min followed by 2 hr of reperfusion. A normotensive control group was compared with animals rendered hypertensive with phenylephrine during the ischemic and reperfusion times. In the hypertensive group, systolic blood pressure was raised from 106 to 161 mm Hg and peripheral vascular resistance from normal to 3600 dyn-sec-cm-5. Regional left ventricular wall thickness, mitochondrial function, sarcoplasmic reticulum Ca2+ uptake, tissue calcium, water content, and hemorrhage were evaluated. Compared to controls the hypertensive group had (1) loss of systolic wall thickening with increased diastolic wall thickness in the reperfused zone, (2) intramyocardial hemorrhage in the area of reperfusion, (3) significant impairment of oxidative phosphorylation by mitochondria isolated from the reperfused zone, (4) a marked reduction in the rate of Ca2+ uptake by sarcoplasmic reticulum vesicles, and (5) an increase in ischemic tissue calcium. Thus, hypertension associated with revascularization of acutely ischemic myocardium may accentuate myocardial damage.
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PMID:The adverse effect of systemic hypertension following myocardial reperfusion. 660 May 6

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

Despite the use of cold blood potassium (CBK) cardioplegia, the severely impaired myocardium and/or long ischemia time continue to be a challenge. Because of the association of Ca++ with cell injury and death, the use of Ca++ entry blockers is logical. Investigation of cold blood diltiazem (CBD) revealed no advantages over CBK cardioplegia. The combination of potassium and diltiazem is appropriate because of their different mechanisms of action. Ten dogs had 1 hour of myocardial ischemia with topical ice (temperature 7 degrees +/- 2 degrees C) after coronary perfusion with 200 ml of cold blood (5 degrees +/- 1 degree C) containing potassium (30 mEq/L) and diltiazem (400 micrograms/kg). Eight dogs had 2 hours of ischemia after perfusion with 200 ml of cold blood containing potassium (30 mEq/L) and diltiazem (200 micrograms/kg) and reperfusion every 30 minutes with 100 ml of cold blood containing KCl (30 mEq/L) and diltiazem (100 micrograms/kg). Six dogs received the same treatment as the previous group except that diltiazem was increased to 1,600 micrograms/kg for all four perfusions. Baseline studies were repeated after 60 minutes of reperfusion without the use of Ca++ or inotropic agents. Heart rate, peak systolic pressure, velocity of the contractile element (Vce), maximum velocity of contractile element (Vmax), peak +dp/dt, peak -dp/dt, dp/dt over common peak isovolumic pressure, left ventricular compliance, stiffness and elasticity, and heart water were unchanged from control. Coronary vascular resistance was unchanged in Groups 1 and 2 but declined in Group 3. Creatine phosphate was preserved during ischemia; adenosine triphosphate (ATP) declined. With reperfusion there was continued fall in ATP, ADP, and the adenosine pool. Ultrastructure was well preserved. In 16 of 24 dogs defibrillation was not required, whereas all 48 dogs with CBK and all 13 with CBD required defibrillation. These data suggest that the addition of diltiazem to CBK provides more effective cardioplegia (preservation of creatine phosphate), although ATP and the adenosine pool continued to decline with reperfusion.
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PMID:Cold blood potassium diltiazem cardioplegia. 669 11

Eighteen observations of large-focal damage of the myocardium are analysed which macroscopically simulated myocardial infarction. Histologically the foci were represented by confluent areas of fatty and albuminous degeneration alternating with necrosis of individual cardiomyocytes. This condition is a complication of diseases having signs of intoxication, anemia, disorders of lipid metabolism and water-electrolyte balance combined with ischemic heart disease. The degree of heart function disturbance correlated with both the severity of concurrent diseases and the depth and size of cardiomyocyte damage.
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PMID:[Macrofocal metabolic myocardial damage]. 671 4

In acute myocardial infarction the effect of oxygen administration in modifying infarct size is uncertain. To evaluate this as well as the effects of moderate hypocarbia, four groups of anesthetized dogs were studied experimentally for 2 hours after coronary branch ligation: group I (controls; room air, normal blood gases): group IIA (FIo2 50%, normal Paco2); group IIB (FIo2 50%, low Paco2); and group IIC (50% oxygen given after ligation, normal Paco2). In addition to hemodynamics, the effect of differing blood gas patterns on hemoglobin-oxygen affinity (P50) and ischemic alterations of myocardial electrolyte and water content were evaluated. Hemodynamic changes among the four groups included decreases in LV ejection fraction and cardiac output. The latter was more pronounced in the oxygen treated groups with proportionately greater increases in systemic resistance. P50 increased in all groups, indicating decreased hemoglobin-oxygen affinity; in group IIC this increase was significantly greater than in group I. In all groups an analysis of central and border areas of myocardial ischemia showed loss of potassium and gain of sodium and water, but no beneficial effect on this result by oxygen administration pre or post ligation could be demonstrated. On the contrary, among those dogs administered oxygen the ischemic changes appeared more pronounced than in the control group. Moderate hypocarbia did not modify the myocardial electrolyte and water change. The results of this study do not support the hypothesis that oxygen administration can favorably modify the myocardial changes of ischemia, at least early in the course of myocardial infarction.
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PMID:Effects of oxygen administration and alteration in arterial PCO2 on ischemic myocardial changes following experimental coronary artery ligation. 681 24


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