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

Intravenous injections of ionic contrast media increase extravascular lung water in patients with elevated left atrial pressure, particularly in the presence of myocardial ischemia. The authors compared bolus injections of sodium methylglucamine diatrizoate and iopamidol on extravascular lung water at several levels of left atrial pressure in dogs. Methylglucamine increased lung water by a maximum of approximately 25-30% above baseline levels at low (less than 3 mm Hg), moderate (approximately equal to 15 mm Hg), and elevated left atrial pressures (greater than or equal to 25 mm Hg). At matched pressures, the peak change in lung water in the dogs given iopamidol was +4%, +7%, and +6%, respectively. In dogs with myocardial ischemia, the differences were even more pronounced (+45%, +60%, and +70%, respectively, for ionic media, and +7%, +12%, and +21% for iopamidol). The authors caution against using ionic contrast media in patients with left ventricular dysfunction, particularly associated with ischemia. In such cases, non-ionic media appear safer.
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PMID:Extravascular lung water: effects of intravenous ionic and non-ionic (lopamidol) contrast media during ischemia. 333 Jun 19

In order to estimate the pulmonary blood volume between the pulmonary artery trunk and the left atrium (PBV PAT-LA), simultaneously with the pulmonary extravascular water volume (PEWV) in the chronically stable cardiac patients, we employed the double indicator dilution method using heat as a diffusible indicator and indocyanine green as a non-diffusible indicator. The PEWV was obtained as the extravascular lung thermal volume estimated in the aortic root (LTVAo). In the group of hemodynamically normal patients, in spite of ischemic heart disease (G-N, n = 22), the mean pulmonary artery wedge (PAW) pressure was 9.3 +/- 3.9 mmHg (mean +/- SD), PBVPAT-LA was 8.95 +/- 1.71 ml/kg, LTVAo was 5.71 +/- 1.37 ml/kg and PBVPAT-LA/LTVAo ratio was 1.64 +/- 0.44. In the group of hemodynamically slightly compromised patients with mitral stenosis (G-MS, n = 13), the mean PAW pressure was 14.2 +/- 2.6 mmHg, PBVPAT-LA was 11.12 +/- 2.86 ml/kg, LTVAo was 5.68 +/- 1.41 ml/kg and PBVPAT-LA/LTVAo ratio was 2.02 +/- 0.58. Between the two groups, LTVAo was not statistically significant, whereas the mean PAW pressure, PBVPAT-LA and PBVPAT-LA/LTVAo ratio were all significantly increased in G-MS (p less than 0.05). Neither PBVPAT-LA nor LTVAo correlated with the mean PAW pressure in both groups. From PBVPAT-LA/LTVAo ratio, fluid volume in the intravascular space was greater than that in the extravascular space in both groups. From LTVAo, PEWV in G-MS was identical with that in G-N, in spite of the elevated mean PAW pressure. Therefore, even in the patients with mitral stenosis, the interstitium in the lung is kept "dry" under conditions of the mean PAW pressure below 20 mmHg. The safety factors that prevent pulmonary edema, as evidenced in animal studies, seem to operate effectively in man.
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PMID:Pulmonary blood volume and pulmonary extravascular water volume in men. 389 9

It is widely accepted that extravascular lung thermal volume estimated by the double indicator dilution method with heat as a diffusible indicator reliably reflects pulmonary extravascular water volume. Theoretically, as a premise, the indicator should be preserved during its pulmonary circulation. We therefore investigated the thermal conservation during pulmonary circulation; that is, whether there was good agreement in the cardiac outputs "wherever" the thermodilution curves were recorded; for instance, the pulmonary artery trunk (PAT), giving COPAT,heat and the aortic root (Ao), giving COAo,heat. In the present study, we observed a total of 59 pairs of cardiac outputs in dogs (n = 13), including dogs with overt pulmonary edema, produced either by dextran infusion or by alloxan administration. We also studied a total of 23 pairs of cardiac outputs of human subjects (n = 16) with ischemic heart disease or mild mitral stenosis. A mixture of ice-cold 5% glucose solution and indocyanine green was rapidly injected into the right atrium. The thermodilution curve was immediately recorded in the pulmonary artery trunk, and the thermodilution and dye dilution curves were recorded in the aorta using a conventional Swan-Ganz catheter. The cardiac outputs were calculated manually following the Stewart-Hamilton principle. The results were as follows: In dogs, COPAT,heat averaged 2.47 +/- 1.21 L/min (mean +/- SD), COAo,heat averaged 2.44 +/- 1.12 L/min and the difference was not significant (0.3 less than p less than 0.5). The regression equation was COPAT,heat = 1.01 X COAo,heat + 0.02 (n = 59, r = 0.93, p less than 0.001) and the correlation coefficient was excellent.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Double indicator dilution method using heat and dye to measure pulmonary extravascular water volume]. 391 10

The purposes of this study were to evaluate the effects of acute myocardial ischemia with reperfusion on T1 (spin-lattice) nuclear magnetic resonance (NMR) relaxation times in a canine model and correlate these changes with bulk myocardial water content (%H2O). In 15 dogs the left anterior descending coronary artery was occluded for either 40 minutes (n = 5), 1 hour (n = 5), or 2 hours (n = 5). In 15 additional dogs, matched occlusion periods were followed by 3 hours of reperfusion. T1 of tissue from normal and ischemic myocardium was measured in vitro with a 2.5 kg NMR spectrometer. In the reperfusion animals, the 2-hour group showed significant increases in %H2O and T1 when the ischemic segment of myocardium was evaluated (both p less than 0.01). All but one animal in the 1-hour (reperfusion) group showed increases in both %H2O or T1 in the ischemic segment of myocardium when compared to control segments. The mean values from the ischemic myocardium in the 1-hour group were significantly higher than the values from the matched control segment for %H2O (p less than 0.05) and T1 (p less than 0.05). In the group undergoing 40 minutes of ischemia followed by 3 hours of reperfusion, neither %H2O nor T1 changed significantly. In the nonreperfused animals, neither T1 nor %H2O content increased significantly after 40 minutes. Significant increases were seen in the 1-hour (p less than 0.05) and 2-hour groups (without reperfusion) (p less than 0.01). In addition, the 2-hour occlusion followed by reperfusion animals had significantly greater T1 relaxation times and %H2O than control ischemic animals.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Nuclear magnetic resonance analysis of acute myocardial infarction in dogs: the effects of transient coronary ischemia of varying duration and reperfusion on spin lattice relaxation times. 397 74

The acetylcholine-induced relaxation of isolated coronary arteries is reversed to contraction in the absence of endothelium. The importance of endothelium for the regulation of coronary blood flow remains unclear. We thus tested the effects of acetylcholine on epicardial arteries and on coronary resistance vessels in situ in 8 anesthetized dogs. The left circumflex coronary artery was perfused at constant pressure. Epicardial vasomotion was evaluated by sonomicrometry, the vasomotion of coronary resistance vessels by calculated end-diastolic resistance. Acetylcholine (1 microgram/kg/min i.c.) decreased epicardial resistance by 8.6 +/- 1.6% and end-diastolic resistance by 65.8 +/- 6.3%. The epicardial coronary segment was perfused with distilled water for 65 +/- 5 s to denude it of endothelium. After removal of epicardial endothelium, the decrease in end-diastolic resistance caused by acetylcholine was unchanged (59.6 +/- 1.2%); however, epicardial resistance was increased by 7.7 +/- 1.7%. Application of glyceryl trinitrate (5 micrograms/kg/min i.c.) induced a similar decrease of epicardial resistance before and after removal of endothelium:7.9 +/- 1.4 and 6.2 +/- 1.9%, respectively. We conclude that acetylcholine-induced dilation of epicardial coronary arteries is endothelium-dependent in vivo. However, the constriction of epicardial coronary arteries in the absence of endothelium is insufficient to reduce blood flow and to induce myocardial ischemia.
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PMID:Acetylcholine induces constriction of epicardial coronary arteries in anesthetized dogs after removal of endothelium. 402 18

Magnetic resonance (MR) is a new concept in the diagnostics of the cardiovascular system. The basic principle of MR is nuclear magnetism. MR tomography is based on induction and spatial encoding of a nuclear magnetic resonance signal. Due to the high tissue concentration and MR sensitivity, medical MR imaging chiefly uses protons of water, 1H. MR tomography of protons presents highly contrasted images of soft tissue organs with spatial resolution in millimeters. Parametric analysis of the MR signal enables quantitative assessments of physico-chemical tissue properties, blood flow and perfusion. The method is noninvasive and without serious biological side effects. Ionising radiation or traditional contrast agents are not utilized. Using conventional ECG synchronized MR tomography the cardiac and great vessels anatomy are superbly resolved, exceptions being the resolution of coronary vasculature and cardiac valve apparatus. The excellent spatial resolution and flexible spatial image orientation are important advantages of quantitative assessment of cardiac function by MR imaging. Preliminary studies demonstrated clinical utility of tomographic assessments of T1 and T2 relaxation parameters as well as phase angle analysis for definition of myocardial ischemia, blood flow rates and wall motion dynamics. The first comparative studies between imaging modalities in diagnostics of specific cardiac disorders point to a superior anatomic resolution of the heart and vascular morphology by MR tomography. The utilization of MR tomography in cardiovascular medicine is new and it would be premature to assign a definite value to this costly technique in clinical evaluations of patients with heart disease. However, there is unequivocal evidence that MR technology will play a decisive role in cardiology in the future, and MR imaging already represents significant progress in the evaluation of patients with cardiac disease.
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PMID:[Imaging of the heart using nuclear magnetic resonance tomography. I: Tomography]. 404 93

A hypolipidemic agent, pentaerythritol tetranicotinate (niceritrol) yields nicotinic acid upon hydrolysis in vivo, but niceritrol is hardly soluble in distilled water, so that the effects of nicotinic acid on platelet aggregation in vitro were studied. Nicotinic acid inhibited in vitro platelet aggregation induced by ADP, collagen and adrenaline. Twenty patients (61.4 +/- 2.4 years (mean +/- S.E.)) with ischemic heart disease, cerebral infarction, transient cerebral ischemic attack and hypercholesterolemia were given niceritrol orally at 750 mg per day for 8 weeks. Significant decreases in ADP-, collagen- and adrenaline-induced platelet aggregation were observed at 4 and 8 weeks after niceritrol treatment. There was a significant correlation between the rates of changes in platelet aggregation and those in plasma total cholesterol or plasma LDL-cholesterol before treatment and 8 weeks following treatment. The results indicate that niceritrol has inhibitory effects on platelet aggregation not only caused by its direct action on platelet but mediated by its secondary action due to decrease in blood lipids.
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PMID:The anti-platelet effect of niceritrol in patients with arteriosclerosis and the relationship of the lipid-lowering effect to the anti-platelet effect. 408 25

In order to examine the relation between cardiac state and the capacity to excrete a water load, 10 normal subjects and 61 patients with heart disease were studied during water diuresis. Under these conditions, urine flow approximates to the rate of delivery of filtrate, and therefore of sodium, from the proximal tubule of the kidney to the loop of Henle, while free water clearance is a function of distal sodium reabsorption. In 12 patients with complete heart block, ventricular pacing was associated with increased urine flow and free water clearance. Oral propranolol in 3 normal subjects and in 9 patients with intact atrial septa caused a reduction, and oral practolol in 4 normal subjects and 8 patients caused no change. In 6 patients with atrial septal defect, propranolol was without effect. Maximum urine flow correlated with left ventricular end-diastolic pressure but not mean left atrial pressure in 16 patients with chronic rheumatic heart disease. In 7 patients with ischaemic heart disease, maximum urine flow was higher than in those with chronic rheumatic heart disease and similar increase in left ventricular end-diastolic pressure. These results reflect a close relation between proximal tubular sodium reabsorption and cardiac state, and suggest that inappropriate sodium reabsorption at this site may contribute to fluid retention in heart disease.
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PMID:Assessment of proximal tubular sodium reabsorption during water diuresis in patients with heart disease. 439 57

In a study of myocardial magnesium and calcium levels in 1236 samples of heart muscle taken at necropsy in 28 centres in England and Wales, samples from patients who died from ischaemic heart disease had a mean Mg level 23 microgram/g lower and a mean Ca level 4 microgram/g higher than the mean for the total series after allowance had been made for a number of relevant factors. Mg levels were slightly higher and Ca levels slightly lower in sudden than in lingering deaths. There was no evidence of any association between the tissue levels and the levels of Mg or Ca in domestic tap-water, but there was a weak association between mean tissue Mg level and IHD mortality rates in the various towns.
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PMID:Magnesium and calcium in the myocardium: cause of death and area differences. 610 29

In an attempt to arbitrate the reputed clinical efficacy of pulsatile flow during reperfusion in minimizing ischemic injury, 32 mongrel dogs supported by normothermic cardiopulmonary bypass were subjected to 30 minutes (Groups IC and IP) or 60 minutes (Groups IIC and IIP) of global myocardial ischemia. The effect of pulsatile flow (P) initiated during 30 minutes of reperfusion on the recovery of myocardial adenosine triphosphate (ATP) and creatine phosphate (CP) stores, coronary blood flow, and myocardial water content (MWC) was compared to the effect of linear reperfusion (C) in another group of animals. ATP stores, which significantly decreased to 43% and 53% of preischemic levels (Groups IC and IP, respectively, p less than 0.01) and 36% and 31% of control values (Groups IIC and IIP, respectively. p less than 0.001), did not increase with either pulsatile or linear reperfusion. CP stores, depleted 97% during ischemia in all groups, returned to preischemic levels regardless of the mode of reperfusion flow. Coronary blood flow measured 30 minutes after aortic unclamping was not significantly different from control flow in any group. MWC significantly decreased during ischemia from 80.5% +/- 0.8% to 76.5% +/- 1.1% in Group IC and from 81.8% +/- 1.2% to 76.8% +/- 0.8% in Groups IP (p less than 0.05) and returned to preischemic levels with reperfusion. However, following 60 minutes of ischemia, pulsatile reperfusion prevented the significant increase in MWC that accrued after linear reperfusion (80.7% +/- 1.5% to 84.0% +/- 0.7%, p less than 0.05). These data indicate that pulsatile reperfusion initiated after an ischemic injury that results in a 50% or greater depletion of myocardial ATP stores does not restore myocardial nucleotide levels or enhance coronary blood flow, although the pathological increase in MWC may be avoided.
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PMID:Pulsatile reperfusion does not modify global myocardial ischemic injury. 621 20


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