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

The direct manipulation of coronary blood flow to induce regional myocardial ischemia has been almost entirely limited to experimental animal models. Thus, the detection of ischemia-induced left ventricular dysfunction in human subjects has been generally limited to observations made under conditions of diagnostic loading or during spontaneous clinical events. Percutaneous coronary angioplasty requires repeated interruptions of coronary blood flow for periods as long as 1 minute. The resulting appearance of or increase in ischemia-produced changes in myocardial function were detected by two-dimensional echocardiography in 18 patients undergoing angioplasty of 22 coronary stenoses. Accordingly, left ventricular contraction was studied during 52 episodes of regional coronary blood flow interruption and reperfusion in the process of inflating and deflating the angioplasty balloon. Before angioplasty, left ventricular wall motion was normal in 14 patients. There was mild anteroapical hypokinesia in two patients, anteroapical akinesia in one and mild inferior hypokinesia in one. Balloon inflations repeatedly produced new or increased wall motion abnormalities in the distribution of the instrumented coronary artery in 19 (86.4%) of the 22 procedures, but did not alter wall motion during angioplasty of one left circumflex artery lesion, one highly collateralized left anterior descending artery stenosis and one left anterior descending stenosis that had already caused severe anteroapical dyssynergy. Hypokinesia, usually rapidly progressing to dyskinesia, began 19 +/- 8 seconds (mean +/- SD) after coronary occlusion. Wall motion began to normalize 17 +/- 8 seconds after reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sequence of mechanical, electrocardiographic and clinical effects of repeated coronary artery occlusion in human beings: echocardiographic observations during coronary angioplasty. 315 58

A technique for epicardial mapping of segmental myocardial function at multiple sites over both right and left ventricles was developed using a high-resolution, 7.5-MHz, short-focus, miniaturized, M-mode echocardiographic transducer worn on the fingertip. Myocardial function was determined from the extent and time course of systolic thickening and diastolic thinning at each site mapped. The technique was characterized in an open-chest canine model of myocardial ischemia. Ischemia was induced by transient or permanent coronary occlusion in 17 dogs. Acute occlusions produced reduced segmental thickening within 10-15 seconds and, often, overt systolic thinning of ischemic myocardium. Rhodamine fluorescence perfusion maps were compared with echocardiographic maps in nine dogs. Segmental thickening was reduced in perfused segments adjacent to, but not involved by, ischemia, as well as ischemic segments. Reproducibility appeared satisfactory for quantitative analysis of grouped data on multiple segments, and qualitative analysis in individual segments. Initial human studies performed during coronary bypass surgery in 11 subjects showed echocardiographic abnormalities in the six patients with ventriculographic abnormalities and in four with normal ventriculograms. Transmural infarctions were akinetic, showing no change in thickness throughout the cardiac cycle. Hypokinetic segments distal to high-grade coronary stenosis were common, although most segments distal to stenosis contracted normally. Reversal of segmental contraction abnormalities by coronary bypass grafting was shown in three subjects, while worsening of function was seen in previously abnormal segments in two and in a previously normal segment in one subject. Epicardial echocardiographic mapping is a practical method for intraoperative assessment of myocardial function during coronary surgery in man that may enhance our understanding of the pathophysiology of coronary disease and the effects of coronary surgery.
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PMID:Epicardial mapping of segmental myocardial function: an echocardiographic method applicable in man. 698 15

Thallium-201 scintigraphy was performed in 20 normals and 60 patients (pts) with angiographically proven coronary artery disease (CAD) at rest after maximal exercise for evaluation of severity and location of CAD. The Tl-scintigrams were quantified by a Tl-score. The results of the Tl-score were compared with invasive and non-invasive parameters. Sensitivity asnd specificity of the Tl-score in evaluation of CAD was 90%. In normals, there were no significant differences from rest to exercise (Tl-score less than or equal to 1.2). Twenty-six of the pts with CAD, who had no evidence of myocardial infarction, showed a significant increase of Tl-score from 5.0 +/- 1.7 to 8.7 +/- 2.6 after exercise (p < 0.001). In 34 pts with CAD and a history of MI, Tl-score increased from 24.9 +/- 3.1 to 33.3 +/- 3.8 (p < 0.001). Exercised-induced ischemia was assessed by exercise electrocardiography in 48%, by Tl-score in 62% and by angina pectoris in 77%. In 37 pts, the Tl-score was compared with the coronary score, ejection fraction (EF) and local wall motion derived from biplane cineventriculograms. There was a significant correlation between the Tl-score and the EF: y = 79.13 - 1.11 x, n = 74, r = 0.688 (p < 0.001). No correlation was found between the coronary score and the Tl-score. Hypokinetic wall motion disturbances were assessed by Tl-score in 34% only, whereas akinesia and dyskinesia were detected in 86% (p < 0.001). The data suggest that Tl-scintigraphy even with a quantitative Tl-score is not sufficient for exact assessment of extent and severity of CAD.
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PMID:[Quantitative Tl-201 scintigraphy in diagnosis of severity and location of coronary artery disease. Comparison of a Tl-score to invasive and non-invasive parameters (author's transl)]. 744 54

The beta-adrenergic pathway may have a role in the pathophysiology of ischemic syndromes characterised by reversible left ventricular dysfunction, such as myocardial stunning and other clinical conditions of unstable angina or coronary spasms, or chronic reversible left ventricular dysfunction, which might be a consequence of repeated events of short-term ischemia ("repetitive stunning"). A partial-to-total occlusion of the left anterior descending coronary artery in pigs was used to induce short periods of ischemia (total ischemic time 12 +/- 2 min). Hypokinesis and dyskinesis of the myocardium were considered signs of myocardial dysfunction. We found a maintained function of the beta-adrenergic signalling system. Density and affinity of beta-adrenergic receptors were not different in stunned and non-ischemic regions, nor were cyclic AMP and cyclic GMP intracellular contents and ratio, nor well as the ratio of stimulatory/inhibitory G protein a subunits. Our findings are in agreement with a maintained beta-adrenergic signalling system in the pathophysiology of chronic reversible left ventricular dysfunction.
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PMID:Beta-adrenergic receptors and intracellular signalling pathway in stunned and non-ischemic regions of pig myocardium. 1151 95

The medial diencephalon is vital for memory, but it is not known why. The present study tested between the predictions of current hypotheses as to why this region is critical for memory. Lesions were made in the rat mammillothalamic tract, the only diencephalic structure consistently associated with amnesia in humans after ischemia. Decreased activity, as measured by immediate-early gene expression (c-fos), was found in three key sites associated with memory function: the hippocampus, the prefrontal cortex, and the retrosplenial cortex. The specificity of these changes was confirmed by the qualitatively different patterns of immediately-early gene changes seen after amygdala lesions, e.g., hypoactivity in the hippocampus and retrosplenial cortex following mammillothalamic tract lesions but not following amygdala lesions. The mammillothalamic lesion results unify substrates linked to diencephalic and temporal lobe amnesia, and thereby support a new account of diencephalic amnesia that emphasizes multiple dysfunctions across hippocampal, retrosplenial, and prefrontal areas. This account suggests a role for the mammillary bodies that is independent of their hippocampal inputs.
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PMID:Hippocampal, retrosplenial, and prefrontal hypoactivity in a model of diencephalic amnesia: Evidence towards an interdependent subcortical-cortical memory network. 1928 Jun 62