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

Silent myocardial ischemia (SMI) is a common ischemia process which can be defined as objective evidence of myocardial ischemia without chest pain or other equivalent indications. SMI can occur in totally asymptomatic patients, as well as in patients who have documented coronary artery disease (CAD) and who, on exercise and/or during Holter monitoring, may show ischemic changes. The precise mechanism for pathogenesis and pathophysiology of SMI remains to be clarified. A great deal has been learned about the role of beta-adrenergic receptors, adenylyl cyclase, and guanine nucleotide binding proteins (G proteins) in the myocardial ischemic process of SMI. Moreover, standard exercise test and long-term ECG recordings have proved to be of great value, especially when performed jointly, however, in this field there is still room for expanded knowledge. Pharmacological interventions to date have demonstrated the beneficial effects of beta-adrenergic receptor antagonists and/or calcium antagonists as contributing substantially to reducing both frequency and duration of SMI episodes. However, therapeutic options to improve the prognosis of SMI appear to be limited.
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PMID:An update to silent myocardial ischemia: pathophysiological, diagnostic, and therapeutic approaches. 197 87

Questionnaires were sent to 61 Norwegian hospitals treating acute coronary syndromes, and 90% replied. Thrombolytic drug treatment is now the routine when the history of chest pain is short and ischemia appears in ECG. Use of glyceryl trinitrate and beta blocking drugs varies considerably, as does the use of oral anticoagulants and platelet inhibitors. Practice also varies in unstable angina. However, a combination of aspirin, intravenous nitrate, and betablockers is common. Several treatment regimens have an uncertain scientific foundation. The varying practice reflects international scientific debate.
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PMID:[Drug therapy of acute myocardial infarction and unstable coronary syndrome]. 197 6

The object of this study was to assess the usefulness of the dipyridamole-echocardiography test in the early evaluation of coronary artery bypass grafting, when the use of an exercise stress test is precluded. We studied 39 consecutive patients (37 men and two women, mean age 57.3 years) referred to our institute for elective coronary artery bypass. Five patients had single, 12 patients double, 20 patients triple vessel disease, and two had left main stem disease. Nineteen left internal mammary artery grafts, 20 sequential grafts, and 39 single vein grafts were performed. All the patients were subjected to the test before (time range 1 to 3 days) and after (time range 6 to 10 days) the operation in the absence of therapy. Dipyridamole was administered intravenously 0.56 mg/kg over 4 minutes (low dose); if no effect was apparent, an additional 0.28 mg/kg over 2 minutes (high dose) was given. During the test, blood pressure and a twelve-lead electrocardiogram were monitored. An arbitrary wall motion score was derived by dividing the left ventricle into six regions and grading from 0 to 3-normokinetic, hypokinetic, akinetic, and dyskinetic zones. Preoperatively the test was positive in 38 patients as evidenced by wall motion abnormalities (36 patients had electrocardiographic changes) and in one patient by electrocardiographic changes and chest pain; 22 tests were positive after the low dose and 17 after the high dose. Angina was present in 33 patients. Mean wall motion score was 1.64 per patient in the basal condition and 4.03 per patient after the test (p less than 0.001). After coronary bypass in three patients the test was positive at the same dosage that was used preoperatively, as shown by wall motion abnormalities (in two patients by electrocardiographic changes, as well). Four patients had symptoms. Furthermore, at 6 months' follow-up, a treadmill stress test performed in these three patients was positive for ischemia and angina. The wall motion score was 1.25 per patient in the basal condition and 1.53 per patient after the test (no significant difference). When the preoperative wall motion score obtained after dipyridamole echocardiography was compared with the postoperative score, a statistically significant difference was seen: 4.03 per patient versus 1.53 per patient (p less than 001). In eight patients we observed an improvement of basal myocardial contractility after the operation, which indicates the reversibility of wall motion abnormalities observed before coronary bypass. In conclusion our data show that the dipyridamole-echocardiography test is a suitable method for the early assessment of bypass grafting when other methods, exercise dependent, are not indicated.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Role of dipyridamole-echocardiography test in the evaluation of coronary reserve after coronary artery bypass grafting. 198 52

Coronary angioplasty without prior thrombolytic therapy was performed in 383 patients with acute myocardial infarction (AMI). Patients were divided into 2 groups depending on whether they were candidates or non-candidates for thrombolytic therapy. Patients were not considered thrombolytic candidates if they: (1) presented in cardiogenic shock, (2) were greater than or equal to 75 years of age, (3) had had coronary artery bypass surgery or, (4) had a reperfusion time of greater than 6 hours. Thrombolytic and nonthrombolytic candidates had similar rates of reperfusion (92 vs 88%), nonfatal reinfarction (6.0 vs 5.9%) and recurrent myocardial ischemia (1.8 vs 0%). Thrombolytic candidates had a lower mortality rate (3.9 vs 24%, p less than 0.0001) and a lower incidence of bleeding (4.6 vs 10.9%, p less than 0.05). Improvement in left ventricular ejection fraction at follow-up angiography was 4.4% in thrombolytic and 10.5% in nonthrombolytic candidates (p less than 0.002). Ejection fraction improved most in patients with anterior wall AMI (7.7% in thrombolytic candidates, 15.1% in nonthrombolytic candidates) and in patients with reperfusion times greater than 6 hours (14.2%). These outcomes suggest that direct coronary angioplasty is a viable alternative method of reperfusion in patients with AMI who are candidates for thrombolytic therapy. Nonthrombolytic candidates are a high-risk group of patients. Direct coronary angioplasty may be beneficial in certain subgroups, especially for patients in cardiogenic shock and for patients presenting greater than 6 hours after the onset of chest pain with evidence of ongoing ischemia.
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PMID:Outcomes of direct coronary angioplasty for acute myocardial infarction in candidates and non-candidates for thrombolytic therapy. 198 7

One hundred sixteen patients were evaluated to determine the ability of single photon emission computed tomographic (SPECT) thallium-201 exercise and redistribution imaging to detect silent ischemia secondary to restenosis in asymptomatic patients after single and multiple vessel percutaneous transluminal coronary angioplasty and the findings were compared with SPECT imaging detection of restenosis in symptomatic patients. The value of exercise electrocardiography (ECG) and the amount of ischemic myocardium in symptomatic and asymptomatic patients were determined. Forty-one patients were asymptomatic after angioplasty; 77% of these had chest pain before angioplasty. Seventy-five patients had chest pain after angioplasty; 99% of these had chest pain before angioplasty. Restenosis occurred in 61% of asymptomatic and 59% of symptomatic patients and in 46% of the vessels in both asymptomatic and symptomatic patients. Sensitivity, specificity and accuracy for detection of restenosis by SPECT in individual patients were 96%, 75% and 88% versus 91%, 77% and 85%, respectively, in the asymptomatic versus symptomatic groups (p = NS). Sensitivity, specificity and accuracy for restenosis detection in individual vessels were 90%, 89% and 89% versus 84%, 77% and 84%, respectively, in the asymptomatic and symptomatic groups (p = NS), with similar results for the three major arteries. Sensitivity and accuracy of exercise ECG were significantly less than those of SPECT imaging for the patients with silent (40% and 44%) and symptomatic (59% and 64%) ischemia (p less than 0.001). Restenosis of vessels in the patients with silent and symptomatic ischemia was associated with an equal amount and degree of severity of ischemic myocardium in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Silent ischemia after coronary angioplasty: evaluation of restenosis and extent of ischemia in asymptomatic patients by tomographic thallium-201 exercise imaging and comparison with symptomatic patients. 199 87

Indications for coronary angioplasty have expanded to include patients with unstable acute ischemic syndromes, severe multivessel coronary artery disease and impaired left ventricular function. Several mechanical approaches have been developed as adjuncts to high risk coronary angioplasty to improve patient tolerance of coronary balloon occlusion and maintain hemodynamic stability in the event of complications. These percutaneous techniques include intraaortic balloon counterpulsation, anterograde transcatheter coronary perfusion, coronary sinus retroperfusion, cardiopulmonary bypass, Hemopump left ventricular assistance and partial left heart bypass. The intraaortic balloon pump provides hemodynamic support and ameliorates ischemia by decreasing myocardial work; it may be inserted for periprocedural complications or before angioplasty in patients with ischemia or hypotension. Anterograde distal coronary artery perfusion may be accomplished passively through an autoperfusion catheter or by active pumping of oxygenated blood or fluorocarbons through the central lumen of an angioplasty catheter. Synchronized coronary sinus retroperfusion produces pulsatile blood flow via the cardiac veins to the coronary bed distal to a stenosis. Both perfusion techniques limit development of ischemic chest pain and myocardial dysfunction in patients undergoing prolonged balloon inflations. Percutaneous cardiopulmonary bypass provides complete systemic hemodynamic support which is independent of intrinsic cardiac function or rhythm and has been employed prophylactically in very high risk patients before coronary angioplasty or emergently for abrupt closure. These and newer support devices, while associated with significant complications, may ultimately improve the safety of coronary angioplasty and allow its application to those who would otherwise not be candidates for revascularization.
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PMID:Percutaneous support devices for high risk or complicated coronary angioplasty. 199 99

Coronary artery disease is an important and frequent complication of peripheral vascular patients (ASO). Therefore a non-invasive screening method is needed to decide the surgical indication for peripheral vascular patients. We studied the usefulness of stress scintigraphy (SSG) by using a bicycle ergometer. Forty-nine patients with chest pain or ECG abnormality were subjected to this study. Twenty-seven patients had coronary arteriography (CAG) performed on them. The redistribution image was noted 39 of the 49 patients who actually performed SSG. CAG was performed on 27 patients, and significant stenosis of the coronary artery was noted in 26 of them. Twenty-three of the 49 patients stopped exercising due to leg pain, but 10 out of 12 patients were noted in the redistribution image in 201Tl scintigraphy to have significant stenosis (sensitivity 83%). It is reported that SSG using a bicycle ergometer can detect ischemia with less stress than when a treadmill exercise test is used. In this study, 23 out of 49 patients stopped exercising due to leg pain but a high sensitivity of 83% was noted in these patients. This sensitivity was thought to be evidence enough to detect coronary artery disease in peripheral vascular patients. In summary, SSG is a useful screening method to detect coronary artery disease in peripheral vascular patients (ASO).
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PMID:[Usefulness of stress scintigraphy on screening coronary artery disease in peripheral vascular patients]. 201 95

Abnormal small coronary artery function may cause limited coronary flow responses to stress, resulting in anginal symptoms and ischemia in some patients with chest pain despite angiographically normal coronary arteries. To assess the exercise hemodynamic correlates of coronary flow abnormalities measured in the cardiac catheterization laboratory, 105 patients with microvascular angina (defined as an increase in coronary vascular resistance during pacing stress after ergonovine administration in the absence of significant epicardial constriction and associated with provocation of the patient's typical chest pain) and 27 patients without any coronary flow abnormality (normal) were analyzed. Of the 105 patients with microvascular angina, 75 had normal electrocardiographic responses to treadmill exercise testing, 22 had ischemic responses, and eight had bundle branch block during exercise. All 27 normal patients had normal electrocardiographic responses to exercise. Patients with ischemic electrocardiographic responses (0 +/- 7%, p less than 0.01), and those with bundle branch block (-2 +/- 6%, p less than 0.01) had abnormal left ventricular ejection fraction responses to exercise compared with the normal group, who demonstrated an 8 +/- 6% increase in left ventricular ejection fraction by radionuclide angiography during exercise, and microvascular angina patients with a normal electrocardiographic response to exercise, who demonstrated a 5 +/- 7% increase in ejection fraction. Although the microvascular response to ergonovine was no different among the three microvascular angina exercise groups, the administration of dipyridamole caused less coronary vasodilation in those patients with apparently ischemic or bundle branch block responses to exercise compared with those with normal electrocardiograms during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Comparison of exercise testing with studies of coronary flow reserve in patients with microvascular angina. 202 51

To know whether the pathogenesis of impending myocardial infarction(IMI) could be predicted by the direction of ST segment shifts during an ischemic chest pain, we studied 62 patients with IMI and undergoing emergent coronary angiography(CAG). They were selected from a consecutive number of 474 patients with unstable angina. IMI was defined when patients had more than 2 episodes of chest pain at rest under intensive pharmacological interventions after their CCU admission, and at least one of those was not relieved by nitroglycerin given intravenously. They were divided into 2 groups according to ST segment shifts during chest pain; 35 patients with ST elevation (G-1) and 27 patients with ST depression (G-2). The time of CAG was individually determined in each patient according to the severity of illness. Those with acute MI within 3 months before the study and 24 hours following the chest pain just before CAG were excluded from the study. New onset angina accounted for 49% in G-1 and 4% in G-2(p less than 0.01). Average history length of IMI, frequency of symptoms after CCU admission, and interval from the last symptom to CAG were similar in each groups. Single vessel disease was more predominant in G-1 than in G-2 (54% vs 11% p less than 0.01). Intracoronary thrombus(IT) in an ischemia related artery(IRA) was found in 97% of G-1 and 22% of G-2(p less than 0.001), while complex lesions(CL) proposed by Ambrose as another genesis of IMI were in 26% of G-1 and 74% of G-2(p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Clinical significance of ST segment shifts during chest pain in predicting the pathogenesis of impending myocardial infarction]. 202 79

The sensitivity of the surface 12-lead electrocardiogram and that of standard (limb-lead) monitoring for the detection of ischemia during percutaneous transluminal coronary angioplasty were compared in 115 patients. The purpose was to identify the electrocardiographic leads that provide the most sensitive indicators of coronary ischemia during percutaneous transaluminal coronary angioplasty and to evaluate the "ischemic fingerprint" that is obtained with 12-lead electrocardiogram during balloon inflation as a predictor of abrupt reocclusion after successful percutaneous transaluminal coronary angioplasty procedures. During balloon inflations of 30 seconds, ischemia was detected in 61 of 145 vessels (42%) by limb-lead monitoring alone versus 130 of 145 vessels (90%) by 12-lead electrocardiography (p less than or equal to 0.001). In the nine patients (7.8%) who experienced abrupt reocclusion within 24 hours, the electrocardiogram during chest pain after percutaneous transaluminal coronary angioplasty was identical to that obtained during percutaneous transaluminal coronary angioplasty ("ischemic fingerprint"). None of the six patients who had chest pain after percutaneous transaluminal coronary angioplasty without evidence of abrupt reocclusion reproduced their ischemic fingerprint. The suggested optimal leads for monitoring ischemia are as follows: left anterior descending coronary artery, V2, and V3; circumflex artery, V2, and V3; and right coronary artery, III and aVF.
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PMID:Twelve-lead electrocardiographic evaluation of ischemia during percutaneous transluminal coronary angioplasty and its correlation with acute reocclusion. 203 73


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