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)

A study of neurohumoral and functional determinants of the advance of Ischemic heart disease in 39 patients with unstable stenocardia with positive results of loading tests (transesophageal electrocardiostimulation and veloergometry) allowed to reveal a significant reduction of the coronary reserve and regional dysfunction of the myocardium that interrelated with changes of the prostacyclin/thromboxane balance, increase of vasopressin with unchanged angiotensin II value and increased marker of the functional state of thrombocytes--beta-thromboglobulin. These changes may be one of the leading links in the pathogenesis of destabilization.
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PMID:[Neurohumoral and functional determinants of destabilization in patients with acute forms of ischemic heart disease]. 183 6

To examine whether acute myocardial ischemia activates the coagulation system and platelet activation in the coronary circulation, we measured plasma levels of fibrinopeptide A and beta-thromboglobulin in the coronary sinus and the aortic root simultaneously in 15 patients with coronary spastic angina before and after the left coronary spasm induced by intracoronary injection of acetylcholine and in 15 patients with stable exertional angina before and after acute myocardial ischemia induced by rapid atrial pacing. Fifteen patients with chest pain but normal coronary arteries and no coronary spasm served as controls. The coronary sinus-arterial difference of fibrinopeptide A increased markedly (p less than 0.001) from 0.1 +/- 0.2 to 4.3 +/- 0.7 ng/ml after the anginal attacks in the coronary spastic angina group. However, fibrinopeptide A levels remained unchanged after the attacks in the stable exertional angina group and after intracoronary injection of acetylcholine in the control group. Plasma beta-thromboglobulin levels remained unchanged after the attacks in both patient groups and after acetylcholine in the control group. Our data indicate that coronary spasm induces thrombin generation and may lead to thrombus formation in the coronary artery involved, but pacing-induced ischemia does not activate the coagulation system.
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PMID:Fibrinopeptide A is released into the coronary circulation after coronary spasm. 214 92

The role of platelets in the pathogenesis of acute myocardial ischemia is not yet agreed upon. In this study, the gradient of plasma beta-thromboglobulin concentration between coronary sinus and aorta was used as an indicator of platelet activation within the coronary circulation. Blood samples were drawn before and after injection of ergonovine maleate in patients without fixed coronary stenosis in whom significant coronary spasm was induced by ergonovine (n = 8, Group 1), patients with significant stenosis (greater than or equal to 75%) of the left anterior descending artery and positive ergonovine test (n = 7, Group 2) and patients with significant stenosis of left anterior descending coronary artery and negative ergonovine test (n = 11, Group 3). Fifteen patients with normal coronary arteries who were negative in the ergonovine test served as controls (Group 4). After the ergonovine test, all Group 1 patients revealed a significant increase of beta-thromboglobulin gradient (P less than 0.001), while those in other groups did not. Additionally, the gradient after the ergonovine test of Group 1 patients was larger than those of the other groups (P less than 0.01). All blood samples after the ergonovine test were collected before or at the onset of angina attacks. These results suggest that platelet activation within the coronary circulation has some pathogenic role, probably as an aggravating factor, in coronary artery spasm.
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PMID:Beta-thromboglobulin release within coronary circulation--a potential role of platelets in ergonovine-induced coronary vasospasm. 241 66

There is increasing evidence that platelets play an important role in the pathogenesis of acute ischemic heart disease. Therefore an understanding of factors that influence platelet performance is important. This study was undertaken (1) to characterize during evolving myocardial infarction platelet activity in the peripheral circulation and across the ischemic/infarcting myocardial compartment, the locus of presumed platelet hyperactivity, and (2) to evaluate the effects of prostacyclin (PGI2), a most potent antiplatelet agent and vasodilator. A total of 59 patients with evolving myocardial infarction were studied. Twenty-two patients were instrumented with arterial and coronary sinus catheters and received intravenous infusion of PGI2, 13 +/- 4.5 ng/kg/min (mean +/- SD), for 90 min. In 15 patients with anterior myocardial infarction, transcardiac platelet function and response to PGI2 were studied. Plasma levels of beta-thromboglobulin (beta-TG) and of thromboxane B2 (TxB2), in vivo measures of platelet activity, were elevated three- and 10-fold. 6-Keto-prostaglandin F 1 alpha, the stable end product of PGI2, was less than 10 pg/ml, reflecting a leftward shift of the TxB2/PGI2 ratio. Platelets circulating during evolving myocardial infarction ("ischemic platelets") were hyperaggregable in response to ADP and relatively resistant to PGI2, both in vivo and in vitro. Concentrations of platelet cyclic AMP and the cyclic AMP response to PGI2 were diminished. The platelet hyperreactivity, expressed by plasma beta-TG, platelet aggregation, and PGI2-induced inhibition of aggregation, was most intense early during infarct evolution and decreased with time. The increased platelet performance resulted in "platelet fatigue," indicated by decreased contents of beta-TG of the ischemic platelet and decreased TxA2 production in response to collagen. However, the ischemic platelet produced twice normal TxA2 in response to arachidonic acid (stimulus and substrate), demonstrating a heightened metabolic capacity. TxA2 was produced across the ischemic/infarcting compartment in 10 of 15 patients with anterior myocardial infarction. The antiplatelet effect of PGI2 was greatly diminished. In summary, the data define an abnormal pattern of platelet behavior during evolving myocardial infarction, characterized by a proaggregatory environment, heightened platelet reactivity in both the peripheral and coronary circulation, and relative resistance to PGI2. The clinical consequences of the data are that the patient in the acute phase of myocardial infarction may benefit from suppression of platelet function and requires significantly greater doses of PGI2 than normal subjects.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Systemic and transcardiac platelet activity in acute myocardial infarction in man: resistance to prostacyclin. 293 81

There is increasing evidence that platelets play an important role in the pathogenesis of acute ischemic heart disease. Therefore, an understanding of factors which impact on platelet performance is important. The present study was undertaken 1. to characterize during evolving myocardial infarction (MI) platelet activity in the peripheral circulation and across the ischemic/infarcting myocardial compartment, the locus of presumed platelet hyperactivity, and 2. to evaluate the effects of prostacyclin (PGI2), a most potent antiplatelet agent and vasodilator. A total of 59 patients with evolving MI were studied. 22 patients were instrumented with arterial and coronary sinus catheters and received intravenous infusion of PGI2, 13 +/- 4.5 ng/kg/min (mean +/- SD), for 90 minutes. In 15 of these patients, who had an anterior MI, transcardiac platelet function and response to PGI2 were studied. The results are as follows: Plasma levels of beta-thromboglobulin (beta-TG) and of thromboxane B2 (TxB2), in vivo measures of platelet activity, are elevated three and ten fold. 6-keto-prostaglandin F1 alpha, the stable end product of PGI2, is less than 10 pg/ml, reflecting a leftward shift of the TxB2/PGI2 ratio. Platelets, circulating during evolving MI ("ischemic platelets") are hyperaggregable in response to adenosine diphosphate and relatively resistent to PGI2, both in vivo and in vitro. Concentrations of platelet cyclic adenosine monophosphate and the cAMP response to PGI2 are diminished. The platelet hyper-reactivity is most intense early during infarct evolution and decreases with time. Transcardiac measurements indicate that thromboxane is produced across the ischemic/infarcting compartment in ten of 15 patients with anterior MI. The antiplatelet effect of PGI2 is greatly diminished. In summary, the data define an abnormal pattern of platelet behavior during evolving MI characterized by a pro-aggregatory environment, heightened platelet re-activity, both in the peripheral and coronary circulation, and relative resistance to PGI2. The clinical consequence of the data are that the infarct patient in the acute phase may benefit from platelet function suppression and requires significantly greater doses of prostacyclin than normal subjects. The data also suggest future directions for therapeutic manipulation of platelet hyper-reactivity in the setting of acute myocardial ischemia.
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PMID:Platelet hyperactivity in acute myocardial infarction in man--effects of prostacyclin. 293 12

The effect of pacing-induced myocardial ischemia on platelet activation and fibrin formation was investigated in seven patients with severe proximal lesions of the left anterior descending coronary artery to determine if acute ischemia activates the coagulation system. Fibrin formation was assessed from plasma levels of fibrinopeptide A. Platelet activation was assessed by levels of platelet factor 4, beta-thromboglobulin and thromboxane B2. Plasma levels were measured before, during and after acute myocardial ischemia induced by rapid atrial pacing. Blood samples were collected from the ascending aorta and from the great cardiac vein through heparin-bonded catheters. The occurrence of anterior myocardial ischemia was established by electrocardiography and by myocardial lactate extraction. No significant transmyocardial gradients in the levels of fibrinopeptide A, platelet factor 4, beta-thromboglobulin or thromboxane B2 were found at rest, during ischemia or in the recovery period, and levels in the great cardiac vein did not change in response to ischemia. These data indicate that pacing-induced myocardial ischemia does not result in release of fibrinopeptide A, platelet factor 4, beta-thromboglobulin or thromboxane B2 into the coronary circulation, and imply that acute ischemia does not induce platelet activation or fibrin formation in the coronary circulation.
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PMID:Effect of pacing-induced myocardial ischemia on platelet activation and fibrin formation in the coronary circulation. 295 18

During coronary angioplasty, inflation of the balloon within the coronary artery produces transient arterial occlusion and frequently results in myocardial ischemia. Delivery of oxygenated autologous blood to the myocardium at risk during inflation may help mitigate this ischemia. Accordingly, we investigated the feasibility and safety of infusing blood through the central lumen of a dilatation catheter around the guidewire using both a model in vitro and clinical trials. In the tests in vitro, fresh blood was infused at flow rates up to 120 ml/min. Hemolysis was minimal at flow rates of 60 ml/min or less (less than or equal to 0.92 +/- 0.18%), but increased exponentially at higher rates (13.64 +/- 2.37% at 120 ml/min, p less than .002). A similar pattern was observed for potassium release. Platelet and leukocyte counts did not vary significantly, and beta-thromboglobulin and muramidase remained at control levels. Although mean erythrocyte volume did not change, erythrocyte histograms and light microscopy demonstrated a subpopulation of red cell fragments averaging 25 to 40 fl in size at higher rates. A randomized, crossover clinical trial was next performed by delivery of blood perfusion at 60 ml/min to 15 patients undergoing coronary angioplasty. Levels of plasma hemoglobin, beta-thromboglobulin, lactate dehydrogenase, and potassium remained constant before and after the perfusion and the control inflations. The maximum pain score was significantly lower with the perfusion inflation (4.1 +/- 0.8 vs 6.0 +/- 0.9, p less than .003). Relative to baseline, the maximum ST segment elevation during the perfusion inflation (0.5 +/- 0.3 mm) was nearly one-fourth that during the control inflation (1.9 +/- 0.6 mm, p less than .02). Thus, myocardial protection with oxygenated autologous blood perfusion at rates of 60 ml/min appears to be a safe and effective technique that may permit increased inflation time and extend the range of coronary angioplasty to include individuals at high risk for the procedure.
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PMID:Autologous blood perfusion for myocardial protection during coronary angioplasty: a feasibility study. 295 55

Unstable coronary artery disease (CAD) might be related to obstructions of coronary blood flow by platelet aggregates. In 121 men and 43 women admitted to the coronary care unit with suspected unstable CAD, blood samples for tests of platelet function were obtained within 24 hours after admission. Platelet reactivity was tested in vitro in platelet rich plasma as the aggregability towards ADP 1 microM and collagen 1 mg/ml and as the sensitivity to prostacyclin (PSP). The levels of beta-thromboglobulin and platelet factor 4 were determined ex vivo in platelet poor plasma. Patients who developed a nontransmural myocardial infarction (n = 39) or had signs of myocardial ischemia at an exercise test performed within a week (n = 39) were considered to have unstable CAD while patients without signs of ischemia constituted the control group. In the acute phase the PSP was reduced in patients with unstable CAD without any difference between genders. The aggregability towards ADP was higher in women than men but otherwise there were no differences between groups or sexes in any other test in the acute phase. After 12 months there were no differences in PSP between the groups but women had a lower PSP than men. Thus, in the acute phase of unstable CAD, the platelet sensitivity to the inhibitory effects of prostacyclin was reduced which might contribute to the risk for further platelet aggregation, coronary occlusion and myocardial infarction.
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PMID:Platelet reactivity in unstable coronary artery disease. 295 54

Indexes of in vivo platelet activation, beta-thromboglobulin and platelet factor 4 were measured in triplicate in plasma from venous blood of 69 patients with proven ischaemic heart disease (IHD), discarding samples with a ratio of the plasma concentrations of the two proteins less than 2.6, in order to rule out sampling artifacts. Compared with 60 control volunteers, differences were not significant [for beta-thromboglobulin controls (ng ml-1, mean +/- SD) 27.8-8.6, ischaemic patients 32.3 +/- 17.1; for platelet factor 4 controls 4.3 +/- 1.4, ischaemic patients 5.9 +/- 5.7]. However, when patients were stratified according to disease activity (Group I--patients without spontaneous ischaemic episodes at rest during 4 days of continuous electrocardiographic monitoring; Group II--patients with less than 1 ischaemic episode/day; Group III--patients with greater than 1 episode/day), these indexes were increased in 'active' patients (for beta-thromboglobulin, in Group II--32.4 +/- 10.5 ng ml-1, P less than 0.05 vs. Group I; in Group III--42.6 +/- 14.6 ng ml-1, P less than 0.01 vs. Group I, P less than 0.05 vs. control. Platelet factor 4 was increased only in Group III--8.9 +/- 7.2 ng ml-1, P less than 0.05 vs. control). Beta-thromboglobulin and platelet factor 4 were 25.0 +/- 6.7 ng ml-1 and 4.9 +/- 4.8 ng ml-1, respectively, in Group I (P = NS vs. control). A relationship with the number of spontaneous ischaemic episodes at rest was confirmed by linear regression analysis (in Group III patients for beta-thromboglobulin: r = 0.76, P less than 0.01, and for platelet factor 4 r = 0.62, P less than 0.01). Levels were not elevated in patients with previous myocardial infarction without ischaemia at rest and/or patients with stable angina, and were not influenced by the occurrence of a positive exercise stress test. Coronary angiograms of ischaemic patients were analyzed to assess the extent and severity of atherosclerotic involvement: for both extent and severity, involvement was similar in the three groups. These data support the hypothesis of the occurrence of platelet activation in patients with spontaneous angina at rest, but not in other subsets of IHD patients, and establish the possibility of detecting in vivo platelet activation in IHD by means of such circulating markers.
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PMID:Platelet activation in angina at rest. Evidence by paired measurement of plasma beta-thromboglobulin and platelet factor 4. 297 44

We studied the levels of thromboxane B2 (TXB2), 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), platelet aggregability, beta-thromboglobulin and platelet factor 4 in 30 coronary artery disease (CAD) patients and 21 normal subjects during exercise. During treadmill exercise, 13 of 30 CAD patients reported chest pain. We administered a selective thromboxane synthetase inhibitor (OKY-046) for 2 weeks to 10 CAD patients with exercise-induced chest pain and studied its effects. At rest, the plasma TXB2 levels and platelet aggregation were significantly lower in normal subjects than in CAD patients, and there was no difference between CAD patients with and without exercise-induced chest pain. On treadmill testing, plasma TXB2 levels and platelet aggregation increased significantly only in the CAD patients with exercise-induced chest pain. Plasma 6-keto-PGF1 alpha levels in normal subjects were significantly higher than those in CAD patients both at rest and during exercise. After administration of OKY-046, mean exercise time increased significantly from 7.5 to 8.6 min (p less than 0.001). Plasma TXB2 level and platelet aggregation decreased significantly after OKY-046 administration both at rest and during exercise. These results suggest that a marked increase in TXA2, with only a minimal change in PGI2, during exercise may contribute to exercise-induced myocardial ischemia, and that OKY-046 is useful in the treatment of CAD patients.
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PMID:Effects of a selective thromboxane synthetase inhibitor (OKY-046) in patients with coronary artery disease during exercise. 332 62


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