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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Potassium-induced cardioplegia was studied in 38 mongrel dogs supported by normothermic cardiopulmonary bypass and subjected to 60 minutes of aortic cross clamping followed by 30 minutes of reperfusion. A study of preischemic and postischemic ventricular function and myocardial high-energy phosphate compounds, lactate, and glycogen showed substantial preservation of high-energy phosphates and ventricular performance when potassium cardioplegia was used. However, the substantial depression in contractility observed following ischemia nad reperfusion suggests that potassium cardioplegia alone does not provide adequate intraoperative protection of the myocardium.
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PMID:Potassium cardioplegia. An alternate method of intraoperative myocardial protection. 68 94

The in vivo response of cardiac tissue to ischemia is inherently nonuniform, and as a result the drug effects in the latter are subject to great variability. We therefore designed a preparation that could reproducibly respond to uniform ischemia: Langendorff-perfused rabbit hearts in which ischemia was induced by stopping the perfusion. In this preparation therapeutic concentrations of antiarrhythmic drugs have no-to-moderate effects on conduction and excitability of perfused tissue, while markedly depressing these parameters in ischemic tissue. This selectivity for depression of ischemic tissue increases as the ischemia progresses. Antiarrhythmic drugs can in this way markedly attenuate the abnormal electrical activity of the ischemic tissue (responsible for arrhythmias) while minimally affecting this activity in normal tissue.
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PMID:Reproducible and uniform cardiac ischemia: effects of antiarrhythmic drugs. 72 77

In this study we assessed whether various responses to exercise testing could be quantified in order to derive the probabilities of presence of coronary disease, and if present, to assess its severity. A treadmill score based on the exercise response was determined in 405 patients who had both treadmill tests and coronary angiograms. The score was derived using discriminant function analysis, by weighting and combining depth and configuration of ST depression (downsloping, horizontal or slowly upsloping), timing onset and duration of ischemia, grading ventricular arrhythmias, heart rate and blood pressure change, coexistence of exercise-induced chest pain and sex. The treadmill score was effective in detecting coronary disease (lesions with an greater than or equal to 50% narrowing), with a predictive accuracy (PA) (probability that a subject manifesting a positive test has disease) of 87%, a true negative rate (TNR) (probability of a subject with a negative test having no disease) of 80%, and sensitivity of 94%. The treadmill score also detected severe disease (triple-vessel, main left and/or greater than 90% proximal occlusion of the left anterior descending artery), with a PA of 73%, TNR of 79% and sensitivity of 82%. We conclude that the exercise response, expressed numerically as a treadmill score, permits analysis of most of the relevant data from exercise testing, increases test accuracy by 10-15% compared with standard criteria for treatmill test interpretation, and enables the derivation of probability statements for presence and severity of coronary disease. The validity of any prediction on the basis of exercise performance may thus be quantitatively judged.
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PMID:Use of treadmill score to quantify ischemic response and predict extent of coronary disease. 75 97

The isolation medium plays an important part in the assessment of mitochondrial damage following coronary artery ligation. Albumin added to either isolation or incubation medium can protect. A depression of oxygen uptake is found only after prolonged ischemia or in a simple incubation medium. Hence mitochondrial oxygen wastage probably occurs in the infarction process.
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PMID:Mitochondrial metabolism in infarcting myocardium. 81 87

Ischemia-provoking factors such as vasospasm, decreased cerebral perfusion pressure, and intravascular thrombosis may be present after subarchnoid hemorrhage (SAH). When these factors were not present during controlled SAH, a primary depression of cerebral glycolysis associated with normal stores of energy-rich phosphates was found. Although cerebral blood flow usually changes in response to changes in cerebral metabolic needs, this influence on the circulation was not evident in the early hours after SAH. After 3 to 4 hours an erratic decrease in blood flow occurred, probably related to vasospasm, and there were measurable decreases in energy-rich phosphates similar to those occurring after more severe and prolonged ischemias. These findings are indicative of abnormally erratic vascular responses to metabolic cues and may play a role in producing the encephalopathy of SAH.
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PMID:Brain energetics and circulatory control after subarachnoid hemorrhage. 82 8

A man with known coronary heart disease underwent treadmill exercise testing to determine his functional capacity. The test was negative for ischemia. Ventricular ectopic activity was noted at rest and in the recovery period. On the same day, while viewing a sporting event at home, the patient died suddenly. An ambulatory electrocardiographic recording documented ventricular fibrillations as the terminal mechanism. Ventricular ectopic activity and heart rate increased in the two hours prior to death, and ischemic ST-segment depression was noted at the time of the terminal arrhythmia. It is postulated that myocardial ischemia and catecholamine response lowered the threshold to ventricular fibrillation, thus facilitating the emergence of the fatal arrhythmia.
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PMID:Sudden death during ambulatory monitoring. Clinical and electrocardiographic correlations. Report of a case. 83 Feb 11

The sensitivity of myocardial perfusion imaging (MPI) using thallium-201 injected both at rest and during peak exercise was compared to simultaneously recorded 12 lead electrocardiography (ECG) for the detection of transient ischemia in 20 normal subjects and 63 patients with coronary artery disease (CAD). No significant perfusion defects or ECG changes were seen on either the rest or exercise studies in any of the normal subjects. Fifty-six percent of patients with CAD developed new perfusion defects with exercise compared to 38% who developed ischemic ST-segment depression (P less than 0.02). However, when chest pain and/or ST depression were considered indices of ischemia, the sensitivity of exercise testing and thallium-201 MPI was similar. The increased sensitivity of MPI compared to ST-segment depression on the ECG was due to patients with baseline ECG abnormalities and those who failed to achieve 85% of predicted maximum heart rate with exercise. Analysis of the exercise results according to the extent of coronary artery disease revealed a progressive increase in both positive ECGs and MPI with the number of vessels involved. In patients with single vessel disease the MPI was more sensitive than the ECG (P less than 0.02). The combination of the rest and exercise ECG, MPI and chest pain during exercise failed to identify 11% of patients with CAD. Exercise thallium-201 MPI is a useful adjunct to conventional exercise testing particularly when evaluating patients with abnormal resting ECGs, those who develop ventricular conduction defects of arrhythmias during exercise, and those who fail to achieve their predicted heart rate because of fatigue or breathlessness.
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PMID:Thallium-201 myocardial perfusion imaging at rest and during exercise. Comparative sensitivity to electrocardiography in coronary artery disease. 83 Feb 22

The submaximal treadmill exercise test is a valuable noninvasive tool for the diagnosis of overt or latent coronary artery disease (CAD). When submaximal heart rates of 80% to 90% of the predicted maximal rates are attained and when ST-segment depression of at least 1 mm is taken as a criterion of ischemia, testing by any of the various exercise protocols with continuous ECG monitoring affords reasonable specificity and sensitivity. The objectives of testing are to (1) diagnose and determine the severity of CAD, (2) assess functional capacity, (3) observe the natural history of disease, (4) evaluate the effects of medical and surgical treatment, and (5) evaluate responses to physical conditioning or to programs directed toward prevention of CAD. Proper precautions and safety standards minimize the risk of exercise testing.
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PMID:Submaximal treadmill exercise testing of patients with coronary artery disease. 85 49

Twenty-one long-term survivors of out of hospital sudden cardiac death due to ventricular fibrillation underwent radionuclide angiography and myocardial imaging with thallium-201. In 13 patients images were obtained at rest and after maximal treadmill exercise; 11 of these 13 (85 percent) had an image defect in one or both studies. Eleven of the 21 patients (52 percent) had a defect in the image obtained at rest. The magnitude of myocardial image defects was typically great; some patients had an image abnormality without other clinical evidence (angina, S-T depression) of ischemia. The mean ejection fraction, assessed in 16 patients with radionuclide angiography, was 0.41 +/- 0.15 (standard deviation); in 5 of the 16 ejection fraction was normal (more than 0.50) and in 3 it was severely abnormal (less than 0.25). Thus, noninvasive radionuclide studies defined a broad spectrum of ischemic and ventriculographic abnormalities in survivors of sudden cardiac death. Further application of these noninvasive studies may identify those at high risk.
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PMID:Myocardial imaging and radionuclide angiography in survivors of sudden cardiac death due to to ventricular fibrillation: preliminary report. 87 Nov 11

To evaluate whether elevated arterial free fatty acids (FFA) increase myocardial oxygen demand and ischemia, 15 fasting patients with coronary artery disease underwent a standardized atrial pacing test before (PTI) and during (PT2) heparin infusion. The patients were monitored for clinical and electrocardiographic (ECG) manifestations of ischemia. Myocardial extraction of lactate, inorganic phosphate, oxygen and FFA was measured before and during each PT. The control arterial FFA was 0.65 +/- 0.03 micromole/ml and rose to 1.83 +/- 0.16 micromole/ml during heparin influsion. Myocardial oxygen extraction at rest and during PT was not affected by the increase in arterial FFA. Seven patients asymptomatic during PT1 did not develop ischaemic manifestations during PT2. In eight patients with angina during both PTs, increased arterial FFA concentration did not modify the severity of anginal pain, the amount of ST-segment depression and the myocardial balance of lactate or inorganic phosphate. Elevation of arterial FFA by heparin neither increased myocardial oxygen extraction at rest or during pacing nor accentuated ischemic manifestations during PT.
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PMID:Effect of increased free fatty acids on myocardial oxygen extraction and angina threshold during atrial pacing. 87 27


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