Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Because of their potential role in the pathogenesis of sudden death, cardiac arrhythmias in patients with coronary artery disease have become the subject of increasing concern and investigation. A series of studies on the problem of ventricular ectopy as it relates to the entire spectrum of sudden death in coronary disease were carried out utilizing continuous portable electrocardiographic monitoring systems. Evaluation of arrthymias during the entire 3 week in-hospital period after acute myocardial infarction in 83 patients revealed that absence of premature ventricular contractions, including their serious forms (multifocal, paired, R on T phenomenon, frequency 5/min or greater) and ventricular tachycardia in the coronary care unit did not exclude their high incidence rate (premature ventricular contractions 30 percent, serious forms 41 percent, ventricular tachycardia 6 percent) in the late hospital phase. Because late hospital serious forms of ventricular ectopy correlated with arterial hypoxia and elevated left ventricular filling pressure in the coronary care unit and with persistent S-T abnormalities, the extent of left ventricular dysfunction and ischemia with acute myocardial infarction appeared precursors to these arrhythmias. Study of ventricular ectopy in the late hospital phase of acute myocardial infarction indicated that ventricular ectopy and particularly its serious forms and prognostic significance relative to subsequent sudden death after discharge; the extent of predischarge S-T segment alterations was greater in subjects who died suddenly than in survivors, suggesting that persistent ischemia or segmental dyssynergy, or both, predisposed to lethal arrhythmias. Among 86 patients with chronic coronary disease documented by catheterizerization, 87 percent had ventricular ectopy and 62 percent serious ventricular arrhythmias, in contrast to 34 percent and 9 percent, respectively in normal subjects; frequency of serious forms of ventricular ectopy was related to extent of coronary atherosclerosis. Correlation of standard electrocardiograms with continuous Holter electrocardiograms in 101 patients with chronic coronary disease over 24 months revealed that the former modality was insensitive in arrhythmia detection; patients free of ventricular ectopy by serial standard electrocardiograms had a 62 percent incidence rate of serious forms of ventricular ectopy and 6 percent ventricular tachycardia on portable continuous monitoring. Additional studies of patients with chronic coronary disease showed that assessment of both the type of ventricular ectopy and the setting in which it occurs provides the most meaningful characterization of risk of sudden death. These systematic series of observations identify premature ventricular ectopic beats as important and separate risk factors in coronary disease...
Am J Cardiol 1977 May 26
PMID:Identification of sudden death risk factors in acute and chronic coronary artery disease. 87 Nov 8

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.
Am J Cardiol 1977 May 26
PMID:Myocardial imaging and radionuclide angiography in survivors of sudden cardiac death due to to ventricular fibrillation: preliminary report. 87 Nov 11

A model of partial thickness ischemia has been developed using subendocardial S-T elevation without epicardial S-T elevation to detect partial thickness ischemia which is sufficient to cause subsequent necrosis. Subendocardial blood flow in this model (measured with radioactive microsphere techniques) may be reduced to 25 percent of normal (P less than 0.001) by coronary stenosis and tachycardia while subepicardial flow remains normal. Epicardial S-T depression seems to indicate reciprocally subendocardial S-T elevation as long as a layer of nonischemic epicardial muscle is present, but when ischemia becomes transmural, epicardial S-T elevation occurs. Regional pressure-flow relations were determined as distal coronary pressure was reduced at a constant aortic pressure, heart rate and cardiac output. These relations revealed remarkably effective autoregulation of epicardial blood flow concomitant with progressive subendocardial ischemia.
Am J Cardiol 1977 Sep
PMID:Significance of subendocardial S-T segment elevation caused by coronary stenosis in the dog. Epicardial S-T segment depression, local ischemia and subsequent necrosis. 90 35

The temporal evolution of myocardial ischemia was studied in open chest dogs at constant preload, afterload and heart rate. In one group of animals, a variable circumflex arterial stenosis was used to maintain constant distal circumflex arterial hypotension (40 to 50 mm Hg). During a 3 hour period of stenosis, flow in the subendocardial fourth of the ischemic ventricular wall decreased from 0.22 to 0.09 ml/g per min (P less than 0.02), whereas subepicardial flow was not significantly changed. Local vascular resistance, therefore, doubled in the most ischemic area of myocardium. In a second group of animals in which proximal coronary stenosis was held constant and pressure varied, an ischemia-mediated increase in local vascular resistance was also demonstrated. In addition, a reciprocal relation was observed between changes in flow in the left anterior descending coronary region and changes in collateral flow to the region of the circumflex artery. A coronary steal mechanism and an ischemia-mediated resistance increase may be two means by which ischemia is self-propagating.
Am J Cardiol 1977 Sep
PMID:Evolution of regional ischemia distal to a proximal coronary stenosis: self-propagation of ischemia. 90 36

The intraaortic balloon was attempted for therapy in 94 patients and successfully placed in 86. The balloon catheter could not be passed through the femoral or iliac artery in 12 patients (13 percent) of the group; in 4 of these the balloon was inserted through an aortic arch graft. The medical indications were cardiogenic shock and preinfarction angina. Ten of the 14 patients in the group with shock survived when treated with an aortic balloon without emergency surgery. Indications for balloon pumping in the surgical group included inability to wean the patient from the pump-oxygenator, postoperative shock and prophylactic placement of the balloon for poor ventricular function. Inability to remove a patient from pump-oxygenator support was the most common surgical indication, and 47 percent of patients were long-term survivors. Only 1 of the 17 patients for whom balloon pumping was used prophylactically died. Complications occurred in 17 percent of the entire group of 86 patients although the rate for medical patients with cardiogenic shock was 50 percent. The most common complication was arterial insufficiency requiring removal of the balloon. Four patients had permanent damage to the legs from ischemia, one patient requiring bilateral amputation. The overall incidence of serious arterial obstruction was 10 percent. Other complications included balloon displacement with arterial obstruction and pericardial tamponade from anticoagulant agents resulting in death.
Am J Cardiol 1977 Sep
PMID:Results and complications of intraaortic balloon pumping in surgical and medical patients. 90 40

Prinzmetal's variant angina is commonly referred to as a syndrome apart from the usual spectrum of atherosclerotic disease. 2 well-studied patients with this form of angina gave past histories compatible with classical angina. They were found to have, in addition to severe atheromatous lesions, coronary artery spasm resulting in complete obstruction of the vessel during Prinzmetal attacks. The concomitant electrocardiographic ST segment elevations are probably the reflection of transmural ischemia injury resulting from the transient complete occlusion of the corresponding coronary artery. Electrocardiograms taken during milder resting anginal attacks showed minimal nonspecific changes of the electrocardiogram or T wave inversions which may possibly reflect less severe ischemia, secondary to milder coronary spasm. These observations support the possibility that at least in some cases, Prinzmetal's angina may just be a phase in the life history of patients with atherosclerotic disease, during which recurrent severe coronary spasms may occur.
Eur J Cardiol 1977 Oct
PMID:Another look at Prinzmetal's variant angina. 91 86

The effect of reduction in anterior septal arterial flow on the conduction system was studied in seven anesthetized dogs. After 2 hours of occlusion P-Q, A-H, and H-V intervals as well as atrioventricular nodal effective and functional refractory periods were significantly prolonged, sinoatrial conduction time was prolonged and the heart rate was decreased. The duration of the His bundle electrogram was significantly prolonged and the configuration altered. However, QRS duration did not prolong significantly. Fifteen minutes after reperfusion, A-H interval, duration of the His bundle electrogram, effective refractory period and functional refractory period returned toward control values. However, the H-V and QRS intervals as well as sinoatrial conduction time were unchanged after reperfusion. Thus, reduction of anterior septal arterial flow influences not only the distal but also the proximal portion of the conduction system; the most vulnerable part is probably the His bundle. The distal portion of the conduction system is directly influenced by ischemia itself, whereas the proximal portion is influenced through other mechanisms induced by reduction of anterior septal arterial flow.
Am J Cardiol 1977 Nov
PMID:Electrophysiologic effects of anterior septal arterial occlusion. 92 Jun 9

In 12 patients affected by acute myocardial infarction complicated only by ventricular extrasystoles, verapamil was highly effective in the control of the arrhythmias. This result is in agreement with the experimental finding that ischemia inactivates partially or totally early Na+ inward currents, so that fast fibers become slow fibers. The efficacy of verapamil stresses the importance of these fibers which have acquired a slow response in the genesis of arrhythmias due to acute coronary attacks and opens interesting therapeutical prospects.
G Ital Cardiol 1977
PMID:[The antiarrhythmic effects of verapamil in acute myocardial infarction. Considerations on the possible action mechanism (author's transl)]. 92 57

Among 173 patients with typical effort angina (159 men and 14 women) which underwent exercise test and coronary angiography, significant stenosis (greater than or equal to 70%) of one or more of important coronary branches were present in 93,1% of the cases (96,3% among the males and 57% among the females). In the same group the exercise test sensitivity was 88,8%; when 3 coronary branches were involved the sensitivity rises to 94,3%. The 96,6% of patients with positive exercise test had coronary lesions too (true positives). We did not find any correspondence between the site of transient subendocardial ischemia occurred during the exercise test and coronary branch involved, when the stenosis was limited only one important coronary branch. Finally the researche of correlation between the entity of coronary disease (number of coronary vessels involved, entity of left ventricular contractility impairment) and behavior of patient during exercise test, evaluated with different parameters measured at the moment of stopping of exercise (heart rate and threshold work load, rate-pressure product, maximal downsloping of ST segment, different positivity criteria for exercise test) allowed us to show a good correlation only between the extent of coronary involvement and rate-pressure product or maximal downsloping of ST segment.
G Ital Cardiol 1977
PMID:[The effort test in the diagnosis of typical stable effort angina (author's transl)]. 92 65

The selective metabolic effects of glucose and insulin were tested in an intact working swine heart preparation. Supplements of glucose (26.6 millimolar [mM] and insulin (0.025 units/ml) were provided to 18 hearts, 9 control hearts (coronary flow 151 ml/min) and 9 hearts rendered globally ischemic (coronary flow reduced from 167 to 85 ml/min). These hearts were compared with 14 additional hearts (6 control and 8 ischemic) given no supplements (glucose 8.6 mM, no excess insulin). In hearts without supplements, ischemic significantly decreased mechanical performance, myocardial oxygen consumption, fatty acid oxidation and tissue high energy phosphate stores. Glucose consumption was reduced from 133 micromoles (mumol)/hr per g (before ischemia) to 58 mumol/hr per g (P less than 0.05), presumably from inhibition at glyceraldehyde-3-phosphate dehydrogenase. Data for control hearts with excess glucose and insulin were similar to data in control hearts without supplements except that glucose consumption and glycolytic flux were increased. Ischemia in treated hearts, as compared with untreated ischemic hearts, effected similar significant decreases in myocardial oxygen consumption, fatty acid oxidation and high energy phosphate stores and resulted in greater reductions in mechanical performance and in 10 minutes' less average survival time. Glucose consumption was reduced from 483 (before ischemia) to 242 mumol/hr per g (P less than 0.005) and inhibition at glyceraldehyde-3-phosphate dehydrogenase was again noted. Thus, excess carbohydrate and insulin hormone, when infused directly into the ischemic myocardium, did not provide an efficacious increase in either glycolytic flux or energy production. These findings suggest that an alternative explanation for the reported efficacy of glucose-insulin-potassium infusions must be sought.
Am J Cardiol 1976 Jul
PMID:Effects of excess glucose and insulin on glycolytic metabolism during experimental myocardial ischemia. 93 98


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>