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)

Hemodynamic measurements were performed and ECG recorded before and shortly after infrarenal aortic cross-clamping during operation for abdominal aortic aneurysm in five patients without evidence of heart disease (group I) and in ten patients with severe coronary artery disease (group II). All patients sustained an increase in systemic arterial pressure. Group I demonstrated a decrease in pulmonary artery, pulmonary capillary wedge (PCW), and central venous pressures when the aorta was clamped, whereas group II demonstrated an increase. The difference in response of the groups is significant (P less than 0.05). All three patients who responded to cross-clamping with increases of 7 mm Hg or greater in PCW demonstrated myocardial ischemia during cross-clamping. None of the values measured prior to cross-clamping predicted with certainty the response to cross-clamping. Sodium nitroprusside reversed the elevation of left ventricular filling pressure in all three patients, and in two patients, relieved evidence of myocardial ischemia concurrently. In the third patient, ventricular irritability was abolished by lidocaine and did not recur. We conclude that infrarenal aortic cross-clamping may cause myocardial ischemia in patients with severe coronary artery disease. This ischemia may be predicted by a rise in PCW at the time of cross-clamping, and vasodilator therapy is indicated in such patients.
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PMID:Myocardial ischemia due to infrarenal aortic cross-clamping during aortic surgery in patients with severe coronary artery disease. 126 32

The activity of soluble guanylate cyclase (GC) and its regulation in the platelets and heart of normal rats and rats with experimental acute myocardial ischemia provoked by coronary ligation was examined. There was a synchronous reduction in platelet and heart GC activity immediately following 15 minutes after surgery along with a drastically marked drop in genuine baseline activity (with Mg2+) to 19 and 40% in the platelets and heart (both ischemic and intact areas), respectively. Following 24 hours, GC activity insignificantly rose (up to 35.5%) in the platelets with Mg2+, that with Mn2+ remained unchanged; in the ischemic area it decreased much more (to 30%), whereas in the intact area it partially restored (up to 70%). The stimulating effect of DTT on platelet GC activity 15 minutes after the surgery drastically rose (from 2.8 to 8), then returning to normal 24 hours later. The findings show an enhancement in free radical processes typical of ischemia and indicate their high response of platelet GC at the earliest stages. Sodium nitroprusside-induced activation of myocardial GC diminished in the ischemic area in 15 minutes and virtually lacked in 24 hours. There was a less pronounced decrease in GC activation in the intact area. It is suggested that lower enzymatic activatibility is associated with heme loss. The absence of sodium nitroprusside-induced stimulation of platelet GC both in health and in the abnormality under question may be due to primary heme enzymatic deficiency.
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PMID:[Soluble guanyl cyclase of blood platelets and heart of rats with experimental myocardial ischemia]. 135 20

The nitrovasodilators, nitroglycerin and sodium nitroprusside, cause both arterial and venous smooth muscle dilation by the intracellular release of nitric oxide. Nitric oxide activates guanylate cyclase, resulting in an accumulation of cyclic GMP. The endogenous formation of nitric oxide results in vasodilatory activity similar to the nitrovasodilators. Nitroglycerin is commonly used in the treatment of angina pectoris because of its ability to decrease myocardial oxygen consumption. Most likely, this response occurs as a result of a reduction in preload, which can decrease arterial wall tension and improve coronary blood flow. This pharmacologic effect warrants the use of nitroglycerin in the treatment of myocardial ischemia or infarction, congestive heart failure, and hypertension. Sodium nitroprusside is effective in reducing arterial blood pressure in hypertensive crisis as a result of systemic vasodilation leading to a reduction in preload and afterload. Sodium nitroprusside is not as effective in the treatment of angina pectoris or in diminishing of myocardial ischemia because it does not preferentially improve blood flow to ischemic myocardium over nonischemic myocardium. Inhibition of platelet aggregation has been demonstrated with these drugs, but the clinical applications need further investigation. Nursing interventions for the patient on nitrovasodilator therapy include careful hemodynamic monitoring and drug infusion, along with elimination of physical and emotional stimuli that can aggravate the patient's underlying pathology.
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PMID:Pharmacology of the nitrovasodilators. Antianginal, antihypertensive, and antiplatelet actions. 190 76

In 161 patients with different forms of ischaemic heart disease the authors studied changes of the blood viscosity, erythrocyte aggregation and of thrombocytes during treatment with modern antianginal and the thrombolytic agents. Treatment with nitroglycerin in tablets and Sustac revealed no statistically significant differences in the changes of the haemorheological parameters. The mainly thrombocyte disaggregational effect was shown by micristin (aspirin/propranolol in the daily dose of over 120 mg) and verapamil (the daily dose over 160 mg). The use of dipyridamol, trental and nonachlazin was accompanied both by the decrease of functional activity of thrombocytes and by the decrease of the blood viscosity as a result of improvement of the functional properties of erythrocytes. Sodium nitroprusside depressed shortly the aggregation of platelets and decreased the blood viscosity at the expense of the decrease of the haematocrit. The use of streptokinase (avelisine) in patients with acute myocardial infarction was accompanied by defibrinisation of the blood, by marked decrease of the aggregation facility of formed elements of the blood and its viscosity. The results suggest that the haemorheological mechanisms participate in the antianginal effect of the drugs studied.
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PMID:[Blood rheological effects in ischemic heart disease treated with antianginal and thrombolytic agents]. 728 86

Hypertensive emergency is a condition in which there is elevation of both systolic and diastolic blood pressure with the presence of acute target organ disease. Hypertensive urgency is a condition where the blood pressure is elevated (diastolic > 120 mmHg) with the absence of acute target organ disease. Hypertensive emergencies are best managed with parenteral drugs and careful intraarterial blood pressure monitoring. Hydralazine has been widely used in treatment of hypertension in eclampsia and preeclampsia, and its safety has been demonstrated in these patients. Sodium nitroprusside (SNP) has the most reliable antihypertensive activity, which begins immediately after its administration and ends when the infusion is stopped. As with diazoxide, it should be used with caution in patients with impaired cerebral flow. SNP is the preferred drug in obtaining controlled hypotension in patients undergoing neurovascular surgery. Intravenous nitroglycerin is useful in patients prone to myocardial ischemia, but should be avoided in patients with increased intracranial pressure. Esmolol is effective in controlling both supraventricular tachyarrhythmias and severe hypertension. Its short onset of duration of action make it useful in the emergent setting, but because of its negative inotropic effect its use should be avoided in patients with low cardiac output. Verapamil should not be used in patients with preexisting conduction abnormalities. Nicardipine is a potent arteriolar vasodilator without a significant direct depressant effect on myocardium. As with other afterload reducing agents, it should not be used in patients with severe aortic stenosis. Because angiotensin-converting enzyme (ACE) inhibitors generally cause cerebral vasodilatation, enalaprilat may be particularly beneficial for patients who are at high risk of developing cerebral hypotensive episodes secondary to impaired cerebral circulation. Fenoldopam, a selective post-synaptic dopaminergic receptor (DA1) has been shown to be effective in treating severe hypertension with a lower incidence of side effects than SNP. Hypertensive urgencies can usually be managed with oral agents. Oral nifedipine, captopril, clonidine, labetalol, prazosin, and nimodipine have all been shown to be effective in these situations.
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PMID:Management of hypertensive urgencies and emergencies. 852 30

Hypertensive crisis is defined as a severe elevation in BP and is classified as either urgency or emergency. In hypertensive urgency there is no end-organ injury and no evidence that acute BP lowering is beneficial. Indeed, rapid uncontrolled pressure reduction may be harmful. Therefore, in hypertensive urgencies BP should be lowered gradually over 24 to 48 hours using oral antihypertensives. When the cause of transient BP elevations is easily identified, appropriate treatment should be given. When the cause is unknown, an oral antihypertensive should be given. The efficacy of available treatments appear similar; however, the underlying pathophysiological and clinical findings, mechanism of action and potential for adverse effects should guide choice. Captopril should be avoided in patients with bilateral renal artery stenosis or unilateral renal artery stenosis in patients with a solitary kidney. Nifedipine and other dihydropyridines increase heart rate whereas clonidine, beta-blockers and labetalol tend to decrease it. This is particularly important in patients with ischaemic heart disease. Labetalol and beta-blockers are contraindicated in patients with bronchospasm and bradycardia or heart blocks. Clonidine should be avoided if mental acuity is desired. In hypertensive emergency there is an immediate threat to the integrity of the cardiovascular system. BP should be immediately reduced to avoid further end organ damage. Sodium nitroprusside is the most popular agent. Nitroglycerin (glyceryl trinitrate) is preferred when there is acute coronary insufficiency. A beta-blocker may be added in some patients. Loop diuretics, nitroglycerin and sodium nitroprusside are effective in patients with concomitant pulmonary oedema. Enalaprilat is also theoretically helpful, especially when the renin system might be activated. Initial treatment of aortic dissection involves rapid, controlled titration of arterial pressure to normal levels using intravenous sodium nitroprusside and a beta-blocker. If beta-blockers are contraindicated, urapidil or trimetaphan camsilate are alternatives. Hydralazine is the drug of choice for patients with eclampsia. Labetalol, urapidil or calcium antagonists are possible alternatives if hydralazine fails or is contraindicated. For patients with catecholamine-induced crises, an alpha-blocker such as phentolamine should be given; labetalol or sodium nitroprusside with beta-blockers are alternatives. There are few, if any, comparative or randomised trials providing definitive conclusions about the efficacy and safety of comparative agents. Some investigators recommend decreasing the diastolic BP to no less than 100 to 110 mm Hg. A reasonable approach for most patients with hypertensive emergencies is to lower the mean arterial pressure by 25% over the initial 2 to 4 hours with the most specific antihypertensive regimen.
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PMID:Comparative tolerability profile of hypertensive crisis treatments. 970 48