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)

Dipyridamole cardiac imaging is a useful alternative technique to exercise stress testing in the evaluation of patients with ischemic heart disease. Intravenous dipyridamole is still in the investigational phase, while oral dipyridamole is widely available. The hemodynamic effects of dipyridamole include an increase in coronary blood flow (due to coronary vasodilation) which is in excess of the increase in myocardial oxygen consumption and cardiac output. The disparity in the increase in coronary blood flow relative to the cardiac output results in an increase in myocardial thallium activity and an increase in the myocardial/background activity ratio. The quality of the thallium images is better or similar to that of exercise thallium images. The optimal dose of intravenous dipyridamole is 0.56 mg/kg, and of the oral dose it is 300 to 400 mg, although higher doses may be necessary in some patients. Analysis of the thallium images has been to a large extent based on visual inspection of the planar images. Delayed images are helpful to establish the nature of the perfusion abnormalities (transient or fixed). The process of redistribution is based on disparate rates of washout from the normal and abnormal zones. The sensitivity and specificity of dipyridamole thallium imaging, whether intravenous or oral, have been shown in a number of studies to be quite adequate and comparable to that achieved during exercise thallium imaging. Dipyridamole two-dimensional echocardiography has also been used in the detection of coronary artery disease; transient (new or worsening of preexisting) wall motion abnormalities have been found to be a specific marker of coronary artery disease. Transmural as well as regional coronary steal phenomena have been postulated as the mechanism for dipyridamole-induced regional wall motion abnormalities. Compared to exercise two-dimensional echocardiography, dipyridamole echocardiography provides high-quality studies and in higher proportions of patients. The results of dipyridamole thallium imaging have also been extremely important in identifying high-risk patients after acute myocardial infarction or patients with peripheral vascular disease undergoing elective vascular surgery; the presence of a dipyridamole-induced perfusion abnormality identifies patients at high risk for future cardiac events. Thus, dipyridamole cardiac imaging is helpful in the diagnosis of coronary artery disease and in risk stratification.
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PMID:Dipyridamole cardiac imaging. 327 61

Anginal chest pain represents an important cardiac symptom which proved to have a high pretest probability for the existence of potential heart disease. The occurrence of clinically unapparent or atypically exposed myocardial ischemia, as well as discrepancies in effort angina, provide evidence that the release of a nociceptive stimulus does not guarantee pain perception of the same proportion. The connections between sequential nociceptive nerve impulses at different central nervous regions and particularly at non-specified thalamic nuclei allow learning processes in the development of pain perception. The intensity of pain may be altered to a great extent by the anxiety level. The patient might develop habits of vigilance for low threshold abnormal signals generated from the interior of the body; he might, however, also reach a stage of complete pain suppression by centrifugal control of the nociceptive input. Heart pain is probably one of the moderators in a more complex warning system.
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PMID:[Leading symptom of angina pectoris. Psychophysiologic mechanisms of pain perception in chest pain complaints]. 331 12

Coronary artery disease accounts for more than half of the morbidity and mortality associated with abdominal aortic surgery. To improve the results of vascular surgery, the risk of perioperative cardiac ischemia should be evaluated in each patient. Routine coronary angiography demonstrated severe correctable coronary artery disease in 14% of patients who had no history or electrocardiographic evidence of coronary artery disease. Exercise testing before abdominal aortic aneurysm repair will identify patients at high risk of cardiac ischemia. Dipyridamole-thallium imaging will identify high-risk patients before surgery for aortoiliac occlusive disease. Some patients with symptomatic coronary disease who are at extremely high risk should undergo preoperative coronary revascularization. Others should have their vascular surgery deferred, because their cardiac risk may exceed the anticipated benefit of the vascular surgery. Patients at moderate risk may need more intensive intraoperative monitoring. Patients without evidence of cardiac ischemia with stress may undergo vascular surgery with a low risk of perioperative cardiac ischemia. Finally, patients who have evidence of ischemic heart disease should be considered for coronary revascularization following successful vascular repair in order to prolong their survival.
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PMID:Preoperative management of the patient with coronary artery disease before abdominal aortic surgery. 349 47

Urgent coronary revascularization for acute myocardial ischemia results in an increased mortality and morbidity. Deposition of activated platelets and leukocytes into the ischemic myocardium during reperfusion may augment perioperative ischemic injury. Dipyridamole reduces platelet activation and may reduce myocardial deposition and prevent ischemic injury during reperfusion. The effects of dipyridamole on myocardial platelet and leukocyte deposition were evaluated in a canine model of acute regional myocardial ischemia with reperfusion during cardioplegia on cardiopulmonary bypass. Eight dogs underwent left anterior descending (LAD) coronary artery ligation for 45 min followed by cardiopulmonary bypass and release of the ligature during 60 min of cold crystalloid cardioplegic arrest to simulate urgent revascularization. Four dogs were randomized to receive an infusion of dipyridamole perioperatively (50 mg/hr) and 4 dogs served as controls. Autologous platelets were labeled with 111In, leukocytes with 99mTc, and erythrocytes with 51Cr. The labeled cells were infused immediately after cross-clamp release and myocardial biopsies were obtained at 10, 20, 30, and 60 min of reperfusion. Platelets were deposited in the myocardium during reperfusion and four times more platelets were found in the LAD region than the circumflex region. Leukocyte deposition was similar in the LAD and circumflex regions. Dipyridamole reduced both platelet and leukocyte deposition and the reduction was greater in the LAD than in the circumflex region. Myocardial platelet and leukocyte deposition was found after regional ischemia, cardioplegia, and cardiopulmonary bypass. Dipyridamole reduced myocardial platelet and leukocyte deposition and may reduce perioperative ischemic injury.
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PMID:Dipyridamole reduced myocardial platelet and leukocyte deposition following ischemia and cardioplegia. 358 31

In 50 patients with chronic stable angina and in 10 asymptomatic young male volunteers, the behavior of S-wave amplitude was studied during episodes of ischemic ST-segment depression, both induced by exercise testing and occurring during ambulatory electrocardiographic monitoring. With exercise, all patients showed diagnostic ST-segment depression (0.16 +/- 0.05 mV) which, in 49, was associated with an increase in S-wave amplitude. No consistent changes in R-wave amplitude were observed. S-wave amplitude also increased in all control subjects during exercise, but the sum of R and S wave remained constant, while it increased in 42 patients. In the 10 study patients undergoing Holter monitoring we identified 170 episodes of ischemic ST-segment depression, of which 169 were associated with increased S-wave amplitude. Isolated increases in S-wave amplitude without ST-segment changes occurred in 3 of 4 normal subjects. Dipyridamole echocardiography revealed regional wall motion abnormalities in 12 of 21 patients; the changes were invariably associated with increased S-wave amplitude but not necessarily with diagnostic ST-segment depression. An increase in S-wave amplitude is almost invariably associated with subendocardial ischemia, sometimes in the absence of ST-segment changes; this sign could represent a sensitive (although less specific) additional marker of myocardial ischemia.
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PMID:Increase in S-wave amplitude during ischemic ST-segment depression in stable angina pectoris. 359 82

Dipyridamole test, isoproterenol test, and treadmill exercise test were performed in two groups of patients with vasospastic angina (Group 1: 10 patients with 70% or greater coronary narrowings, Group 2: 8 patients with narrowings less than 70%. The results were correlated with coronary anatomy. In Group 1, vasodilation of resistance vessels by dipyridamole elicited ischemic episodes in 9 patients and an increase in myocardial oxygen consumption by isoproterenol caused anginal attacks in 7 patients. None of patients of Group 2 showed positive responses to either drug. All patients of Group 1, and 3 patients of Group 2 gave positive responses to treadmill test. These observations show that several different mechanisms are involved in the pathogenesis of myocardial ischemia in patients with vasospastic angina. Pharmacological interventions have higher specificity than exercise tests in predicting coronary anatomy and are useful for the choice of therapy in the patients.
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PMID:Noninvasive demonstration of underlying severe coronary disease in patients with vasospastic angina. 359 56

A frequent clinical problem is to document the elusive entity of electrocardiographically silent myocardial ischemia. Since echocardiography offers a practical tool to detect reversible mechanical changes due to ischemia, 32 patients with angina on effort, and coronary artery disease, and 15 patients with angina at rest were studied. In all 47 patients electrocardiographic changes during effort or rest pain were inconclusive. Combined 12 lead electrocardiographic and 2-Dimensional echocardiographic monitoring were performed: during ergonovine testing in the 15 patients with angina at rest; during dipyridamole testing in the 32 patients with effort angina and a non diagnostic stress test. Interpretable echocardiograms were obtained in all the patients studied. Positivity of both the Ergonovine-Echocardiographic test and the Dipyridamole-Echocardiographic test was based upon the detection of regional transient asynergy. Of the 15 patients who had chest pain at rest in the absence of diagnostic electrocardiographic changes, Ergonovine-Echocardiographic test was positive in 6 (40%). Of the 32 patients who had chest pain in absence of diagnostic electrocardiographic changes during exercise stress testing, the Dipyridamole-Echocardiographic test was positive in 18 (56%). Echocardiographic monitoring in combination with provocative testing (ergonovine and dipyridamole) may be a practical, non invasive, inexpensive tool which is feasible in all patients with good basal echocardiograms and is able to unmask electrocardiographically silent myocardial ischemia by providing objective mechanical evidence of the ischemic event.
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PMID:Echocardiographic documentation of myocardial ischemia in presence of angina pectoris without ST-T changes. 375 1

Dipyridamole thallium 201 scintigraphy (DTS) was used to screen 116 consecutive patients referred for aortic reconstructive surgery for coronary artery disease (CAD). Thallium redistribution was found to have the best statistical correlation with postoperative myocardial infarction (MI). No MIs occurred after aortic operations among 60 patients with normal scans compared with 8 of 31 patients with abnormal ones. The odds of a patient with abnormalities found by DTS having a postoperative MI were 12 times greater than for those with a normal scan. No symptom or combination of symptoms of CAD was as good as an abnormal DTS in identifying patients at risk. The incidence of MI was 7.0% for patients with symptomatic CAD and 8.5% for those who were asymptomatic. Cardiac complications gradually declined as surgeons gained confidence in the use of DTS, to the point where no postoperative MIs occurred during the final year of the study. DTS approaches the ideal preoperative test for CAD in patients with peripheral vascular disease. The test does not require exercise, is minimally invasive, safe, and of sufficient sensitivity to detect myocardial ischemia in the absence of symptoms. Furthermore, it is cost-effective; only those patients with an abnormal scan and an imperative need for aortic surgical treatment need further cardiac evaluation.
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PMID:Dipyridamole thallium 201 scintigraphy to detect coronary artery disease before abdominal aortic surgery. 379 95

To evaluate the severity of coronary artery disease in patients with severe peripheral vascular disease requiring operation, we performed preoperative dipyridamole-thallium imaging in 54 stable patients with suspected coronary artery disease. Of the 54 patients, 48 had peripheral vascular surgery as scheduled without coronary angiography, of whom 8 (17 per cent) had postoperative cardiac ischemic events. The occurrence of these eight cardiac events could not have been predicted preoperatively by any clinical factors but did correlate with the presence of thallium redistribution. Eight of 16 patients with thallium redistribution had cardiac events, whereas there were no such events in 32 patients whose thallium scan either was normal or showed only persistent defects (P less than 0.0001). Six other patients also had thallium redistribution but underwent coronary angiography before vascular surgery. All had severe multivessel coronary artery disease, and four underwent coronary bypass surgery followed by uncomplicated peripheral vascular surgery. These data suggest that patients without thallium redistribution are at a low risk for postoperative ischemic events and may proceed to have vascular surgery. Patients with redistribution have a high incidence of postoperative ischemic events and should be considered for preoperative coronary angiography and myocardial revascularization in an effort to avoid postoperative myocardial ischemia and to improve survival. Dipyridamole-thallium imaging is superior to clinical assessment and is safer and less expensive than coronary angiography for the determination of cardiac risk.
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PMID:Determination of cardiac risk by dipyridamole-thallium imaging before peripheral vascular surgery. 387 2

Exercise tolerance and heart response were examined by cross-sectional echocardiography before and during exercise tests to assess the effects of aging, training and myocardial ischemia on the cardiac reserve of 40 healthy men, 20 athletes and 25 patients with angina on effort. The cardiac response to exercise can be divided into 4 types according to parameters derived from a short axis section echocardiogram. Type A: The left ventricular end-diastolic volume (LVEDV) increased slightly in the early stage of exercise, and thereafter, the cardiac response was maintained by a gradual increase of myocardial contractility and heart rate. Type B: Initial response to exercise was similar to Type A, but cardiac output was maintained only by an increase of heart rate under additional exercise load. Type C: LVEDV, LVESV (left ventricular end-systolic volume) and contractility remained virtually unchanged throughout the exercise. Type D: The contractility decreased from the early stage of the exercise, and LVEDV and LVESV increased. Most young subjects and all athletes showed Type A response, while in the aged healthy subjects the Type B response was more frequent. Anginal cases tolerating 125-watt load responded as Type B or C, and those tolerating only 75 watts showed Type C or D. All patients in Type D had multi-vessel disease.
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PMID:Evaluation of effects of aging, training and myocardial ischemia on cardiac reserve by exercise echocardiography. 648 43


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