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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This paper describes a method by which antianginal drugs can be evaluated in the dog heart in situ. Myocardial pH was measured continuously by a micro glass pH electrode inserted in the left ventricular endocardial layers of the dog anesthetized with pentobarbital. Occlusion of the left anterior descending coronary artery (LAD) decreased myocardial pH, and release of the LAD restored the pH. The myocardial acidosis induced by ischemia was metabolic in nature and accompanied by a decrease in the levels of adenosine triphosphate and creatine phosphate and an increase in the levels of lactate in the myocardium. Drugs were injected intravenously 30 min after incomplete (partial) occlusion ot the LAD, lasting until 60 min after drug injection. Propranolol, atenolol, and sotalol markedly attenuated the myocardial pH that had been decreased by LAD occlusion. Nitroglycerin, diltiazem, and nicorandil also attenuated the pH, but these drugs were less active in attenuating myocardial acidosis. Dipyridamole, nifedipine, and beta-2 adrenoceptor antagonists were least active in this regard. It is concluded that myocardial pH can be used as an indicator of myocardial regional ischemia and utilized for evaluation of antianginal drugs.
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PMID:A method for evaluating antianginal drugs in experimental animals: assessment of myocardial ischemia by myocardial pH. 287 74

In order to determine their significance during dipyridamole perfusion scintigraphy, symptomatic, ECG, and scintigraphic findings were related to each other, to the hemodynamic response, and to angiographic findings in 73 consecutive patients having coronary angiography within 3 months of scintigraphy. The group having induced "cardiac" pain differed from the group without induced pain only in their higher incidence of induced ischemic ST changes, the "marked" hemodynamic response, and their lower incidence of an "absent" hemodynamic response (all p less than 0.01). Induced ST depression was found only in patients with coronary disease. In this population, dipyridamole-induced pain was a moderately specific marker and induced ST abnormalities a more highly specific marker for coronary disease. However, both were insensitive for coronary disease diagnosis. If induced pain or ST abnormalities in the presence of significant coronary disease were accepted as indicators of ischemia, then scintigraphic abnormalities appeared to be produced by dipyridamole in roughly equal incidence by ischemic and nonischemic mechanisms. Induced ischemia related frequently to an exaggerated hypotensive response with no change in double product, suggesting its cause to be an induced increase in myocardial oxygen demand. Dipyridamole-induced image defects were noted even in the absence of a peripheral hemodynamic response. This indicates that the peripheral response does not always correlate with its central coronary effect and an absent peripheral hemodynamic response does not necessarily invalidate scintigraphic results.
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PMID:The clinical and pathophysiologic implications of pain, ST abnormalities, and scintigraphic changes induced during dipyridamole infusion: their relationships to the peripheral hemodynamic response. 317 78

To assess the significance and accuracy of noninvasive tests in detecting significant coronary artery disease (CAD; greater than 50% stenosis), the Master's exercise test, treadmill exercise test and dipyridamole-loading myocardial perfusion scintigraphy were performed and their results were compared with coronary angiographic findings in 60 patients with angina but without myocardial infarction. Among these, 27 patients had significant CAD. The Master's test performed in outpatient clinics had an 85% sensitivity and a 76% specificity in detecting significant CAD, when the degree of ST depression was equal to or exceeded 1 mm. The sensitivity further improved to 96% by adding chest pain to the criteria; then all patients with multivessel disease or critical ischemia were identified by the Master's test. Treadmill tests performed after admission had a 78% sensitivity and a 67% specificity. When the severity of ischemia was judged either by exercise capacity or the degree of ST depression or the coronary T wave, the treadmill test was superior to the Master's test. Although patients without significant CAD had longer exercise capacity and the higher maximum heart rate in the treadmill test than did those in the Master's test, these trends were similar but less marked in patients with significant CAD. Dipyridamole-loading myocardial perfusion scintigraphy showed an excellent sensitivity and specificity; 96% and 94%, respectively, in detecting significant CAD. It was particularly useful in distinguishing false positive exercise results due to left ventricular hypertrophy and coronary spasm and that in women, from true positive results. In conclusion, the Master's test is a simple and useful method for screening CAD in community hospitals and in outpatient clinics.
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PMID:[Accuracy of the Master's exercise test in detecting significant coronary artery disease]. 326 34

Cardiopulmonary bypass activates and depletes platelets, which may contribute to postoperative bleeding. In addition, activated platelets may be deposited in the coronary vasculature after ischemia and cardioplegia, which may delay recovery of cardiac function and metabolism and may contribute to early bypass graft occlusion. The antiplatelet agent dipyridamole reduces platelet activation and depletion and may decrease postoperative bleeding and transfusion requirements. A prospective randomized trial was conducted in 58 patients undergoing elective coronary bypass operations to compare the effects of oral (19 patients) and intravenous (21 patients) dipyridamole to the results obtained in a control group (18 patients) who received no dipyridamole. Preoperative oral administration of dipyridamole resulted in lower plasma drug concentrations in the early postoperative period than perioperative intravenous administration (p = 0.0001 by analysis of variance). Postoperative arterial platelet counts were highest in the patients receiving intravenous dipyridamole, intermediate in those receiving oral dipyridamole, and lowest in the control group (p = 0.03 by analysis of variance). Postoperative blood loss and blood product transfusions were significantly reduced with both oral and intravenous dipyridamole (p = 0.04 by analysis of variance). Dipyridamole preserved platelets and reduced postoperative bleeding. Intravenous dipyridamole resulted in higher platelet counts than oral dipyridamole and may be required to reduce postoperative bleeding in high-risk patients.
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PMID:Dipyridamole preserved platelets and reduced blood loss after cardiopulmonary bypass. 339 55

Dipyridamole testing represents an alternative to exercise stress testing for documentation of ischemia related to coronary artery disease (CAD). In such a case, ischemia is attributed to maldistribution of coronary flow during dipyridamole-induced vasodilation. The present study evaluated the potential role of dipyridamole testing in producing ischemia through a vasospastic mechanism, following rapid withdrawal of vasodilation induced by aminophylline. The possibility was tested in 36 in-hospital patients with variant angina pectoris who underwent dipyridamole infusion (up to 0.84 mg/kg over 10 minutes) with continuous 12-lead electrocardiographic and 2-dimensional echo monitoring. Medications were withdrawn from all patients. The test was pharmacologically stopped with the dipyridamole antidote (aminophylline, 80 to 240 mg intravenously over 1 to 3 minutes) in all patients. Two to 6 minutes after starting aminophylline infusion, 10 patients (28%) developed (greater than 0.10 mV) ST-segment elevation (2.9 +/- 0.8 mm from baseline), always accompanied by obvious asynergy detected by echocardiography, in the same electrocardiographic leads showing spontaneous or ergonovine-induced ST-segment elevation. Nitrates promptly resolved ischemia in all patients. At coronary angiography, 5 of these 10 patients showed significant CAD (greater than 70% lumen diameter reduction of at least 1 major coronary artery), whereas 5 had nonsignificant CAD. The rate pressure product at the onset of ST-segment elevation (after dipyridamole plus aminophylline) was considerably less than that recorded at peak exercise stress test in these patients (9,600 +/- 2,200 vs 18,400 +/- 4,900, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Aminophylline termination of dipyridamole stress as a trigger of coronary vasospasm in variant angina. 342 Nov 66

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

We studied 19 consecutive subjects affected by effort angina using following tests: ecg stress test, stress 201-Tl scan, coronary arteriography; 201-Tl scan, coronary arteriography, hemodynamic, echo 2 D, ecgraphic monitoring during Dipyridamole test (D). Basing on coronary arteriography results we divided patients; in the group A (10 patients with significant stenoses greater than or equal to 50%) stress ecg and scintigraphy were positive in 9 patients; Dipyridamole test induced angor and ecgraphic changes in 5 patients and in 4 left ventricle wall motion disorders, 201-Tl scan was positive in all 9 patients tested. In the group B (9 subjects with no significant stenosis) ecgraphic changes were observed in 2 subjects and 201-Tl scan was positive in 6 subjects; D induced in 2 cases angor, in 1 case ecgraphic changes, in 1 case left ventricle wall motion disorders and the same 201-Tl defects in 6 previously individualized patients. In both groups we observed at coronary arteriography during D identical findings in comparison with the immediately before performed. In our experience D infusion is confirmed as provocative test of ischemia. The same ischemic pattern observed at stress and Dipyridamole scintigraphy in patients with no significant coronary stenosis suggests as pathogenetic mechanism the regional lack of dilatory reserve.
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PMID:[Dipyridamole test and myocardial scintigraphy with Tl-201 in the diagnosis of myocardial ischemic pathology]. 358 12

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

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


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