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)

Physiologic concepts relating to reperfusion of ischemic areas of myocardium may be applied both to acute coronary insuficiency, manifested by angina pectoris, and to restoration of coronary blood flow by coronary bypass procedures, currently employed both in acute myocardial infarction and in chronic myocardial ischemia for relief of angina pectoris. Of the information currently available from experimental studies, much may be applicable to the clinical situation. After acutr transient coronary occlusion mechanical and electrical properties of the ischemic area rapidly return to normal, but there is prolongation of tension development and occurrence of ventricular arrhythmias; implications of these phenomena for clinical coronary ischemia deserve exploration. Following more prolonged coronary ischemia, results of experimental reperfusion appear to be variable and, although restoration of function following several hours of ischemia is possible, certain deleterious effects are often observed in the form of myocardial edema and hemorrhage. Clinical use of bypass procedures in acute myocardial infarction suggests that results may be good, but that deleterious effects are occasionally observed; occurrence of the later requires definition and explanation. Restoration of myocardial blood flow in the presence of normal left ventricular function in chronic coronary artery disease, and failure to reverse functional abnormalities when left ventricular damage has already ensued in the clinical situation, appears to be well established; however, better methods to assess the potential for recovery of function following revascularization are needed in both acute and chronic coronary artery diseases. It is anticipated that more careful exploration of pathophysiology both in the catheterization laboratory and in the operating room may aid this process.
 ...
PMID:Effect of reperfusion in acute ischemia and infarction. 115 38

Maximal exercise tests and angiographic evaluations were obtained in a group of patients before and after myocardial revascularization. Patients were classified on the basis of angiography and operative records. Two primary groups of 33 patients with complete revascularization and 95 patients with postoperative residual ischemia were studied. The residual ischemia subgroups included patients with partial revascularization, progressive coronary atherosclerosis, or graft failure. Patients with complete revascularization had statistically significant improvements in work capacity, maximal heart rate, maximal rate-pressure products, abnormal exercise electrocardiograms, exercise-induced angina pectoris, and atrial gallop sounds. A spectrum of lesser improvements in these measurements was observed in the subgroups with residual ischemia. Total graft failure resulted in no significant improvements in exercise-test parameters. Maximal stress tests provide a useful adjunct to routine clinical follow-up of myocardial revascularization patients. Myocardial revascularization is associated with significant patient palliation as determined by serial stress testing.
 ...
PMID:The spectrum of exercise test and angiographic correlations in myocardial revascularization surgery. 115 27

The sensitivity of rest and stress myocardial perfusion studies using scintillation camera imaging of intravenously administered rubidium-81 (81Rb) in the detection of myocardial ischemia was compared to that of stress electrocardiography by relating results in 40 patients to the degree of stenosis delineated by coronary arteriography. Of 33 patients with greater than 75% stenosis of at least one of the three major coronary vessels (significant stenosis), rest and stress 81Rb imaging detected ventricular ischemia in 29 (88%) whereas simultaneous stress electrocardiography was positive (1 mm or greater horizontal ST-segment depression) in only 19 (58%) of the same patients. Five of the 29 patients who developed stress-induced scintigraphic evidence of ischemia did not develop angina or a positive electrocardiogram with stress. In 31 of the 33 patients with significant coronary stenosis, either the stress scintigram or the stress electrocardiogram was positive. In seven patients with less than 50% narrowing of a major coronary vessel on coronary arteriography, the stress scinitigrams were negative, whereas the stress electrocardiograms were positive in the two of these patients with the syndrome of angina with normal coronary arteriograms. It is concluded that high resolution images of the myocardium can be obtained with 81Rb using the scintillation camera with special shielding, and that rest and stress 81Rb scintigraphy appears to provide greater sensitivity and specificity when compared to stress electrocardiography in the nininvasive identification of significant coronary stenosis.
 ...
PMID:Noninvasive detection of regional myocardial ischemia using rubidium-81 and the scintillation camera: comparison with stress electrocardiography in patients with arteriographically documented coronary stenosis. 115 74

Eight patients who had surgical correction of coronary artery-cardiac chamber fistula at our center and 163 from a review of the literature are presented. The patients are usually asymptomatic, and the diagnosis is suspected by observing a continuous cardiac murmur. Electrocardiographic findings are nonspecific. Angina pectoris or electrocardiographic evidence of severe ischemia are surprisingly uncommon since coronary artery steal syndrome is also rare. Cardiac catheterization with angiocardiography is required to establish the diagnosis and identify the involved coronary artery and the cardiac chamber into which the fistula terminates. Left-to-right shunt flow is usually low (average Qp/Qs = 1.5). Indications for operation are not precise. If there should be a large shunt flow (2.0) and symptoms of heart failure are present, the decision to operate is clearly justified. This situation is unusual, and operation is nearly always performed in an asymptomatic patient in whom the fistula is closed to prevent future symptoms or complications. The operation chosen is generally interruption of the fistula by direct ligation. Sometimes cardiopulmonary bypass is required. The results are good, with low morbidity (3.6% myocardial infarction) and low mortality (2%) justifying the operation, to be carried out prophylactically even in asymptomatic patients.
 ...
PMID:Congenital coronary artery- cardiac chamber fistula. Review of operative management. 118 Jun

Myocardial metabolism had been studied in 54 patients with continuous sampling of arterial (A) and coronary sinus (CS) blood during 8- to 10-min periods of control in sinus rhythm, rapid atrial pacing and recovery. The results showed that 17 subjects were normal or had insignificant coronary artery disease (CAD; nonischemic group = NI); 37 patients had significant CAD (ischemic group = 1) and developed clinical, hemodynamic, and electrocardographic evidence of myocardial ischemia during pacing, characterized by angina, elevated left ventricular end-diastolic pressure, and depressed ST segments. During pacing-induced ischemia the following metabolic abnormalities were detected: (1) myocardial anaerobiosis indicated by lactate % uptake ((A-CS)/AS X 100) of -17.2 +/- 5.0% (mean +/- SE); (2) myocardial loss of K+ suggested by an A-CS difference of -0.25 +/- 0.08 mEq/liter (N=18); (3) small but significant loss of inorganic phosphorus (Pi) of -1.0 +/- 1.4% (N=18); and (4) elevation of CS blood creatine phosphokinase activity (N=5). These metabolic abnormalities were temporally related to the other manifestations of myocardial ischemia and were not seen in the NI; Lactate production and Pi loss occurred in 75 and 55% of the IG, respectively, suggesting that accelerated anaerobic glycolysis was the best indicator of myocardial ischemia in man. K+ loss was an unreliable index in this experimental situation, since tachycardia alone caused significant K+ egress from the heart. Lactate production and K+ loss were reduced by nitroglycerin, which abolished angina and improved hemodynamics and electrocardiographic manifestations. That these metabolic abnormalities were not observed in all 1 patients may have been related to methodology, the random distribution of CAD, and the fact that the chemical composition of the CS blood reflects the metabolic balance of both well oxygenated and ischemic areas of the myocardium.
 ...
PMID:Metabolic indicators of myocardial ischemia in man. 120 71

During an atrial pacing test, a correlative study in myocardial lactate, glucose, potassium, and inorganic phosphate balances was done in 34 patients with clinical evidence of ischemic heart disease. Electrocardiogram was continuously monitored while left ventricular end-diastolic pressure (LVEDP) was measured before and immediately after pacing. Coronary angiograms performed after the pacing test revealed atherosclerotic narrowings in all patients. During pacing, 16 patients developed anginal pain, and their LVEDP increased significantly. The other 18 patients had no angina and no significant change in LVEDP. In these 18 patients, there were no significant changes throughout the pacing study in myocardial balances of lactate, glucose, potassium, and inorganic phosphate. In contrast, the 16 patients with induced angina during pacing showed a significant myocardial production of lactate and a loss of potassium. Myocardial inorganic phosphate loss was not statistically significant. There was no significant change in myocardial glucose extraction during angina, although a slight increase was observed during the 1st min afer pacingmthere was no correlation between the arterial concentration and the myocardial extraction of these substances. N stoichiometric relationship was found between glucose and lactate or between potassium and inorganic phospahte balance; Myocardial extraction and production of lactate correlated best with inorganic phosphate uptake and loss. In the preset study, lactate was a more reliable metabolic indicator of myocardial ischemia than potassium and inorganic phosphate, although these last two substances may be helpful in acheiving a greater accuracy for biochemical diagnosis of ischemia. Myocardial glucose balance was of no value as a metabolic indicator of ischemia in this pacing study.
 ...
PMID:Comparison of changes in myocardial balances of lactate, glucose potassium, and inorganic phosphate during pacing-induced angina. 120 74

In order to reduce the oxygen consumption of the myocardium and preserve the areas around the infarction, still alive but undergoing ischemia, 8 patients with early extension of their infarction were placed under circulatory assistance by intra-aortic counter-pulsation. In 8 patients, the pain disappeared and did not recur, permitting left ventriculography and coronary arteriogrpahy. This examination is often considered high risk, but in no patient in our series, during the acute phase of myocardial infarction, were there any complications. 6 patients underwent operation, and aortic counter-pulsation was used during the post-operative period. In all, eight coronary by-pass operations were carried out and, in one case, part of the ventricular wall was resected. All patients are still alive, none have heart failure or residual angina; the follow-up period is now 2 years for the first case.
 ...
PMID:[Emergency myocardial revascularization with assisted circulation for early extension of infarction]. 122 51

Over the span of two or three days in August, 1972, in two separate communities in eastern Massachusetts two men, one aged 39, the other 66, each without previous overt heart disease, were stung by wasps. Each went into shock rapidly after an interval of over a half-hour developed chest pain and, later, sequential electrocardiographic changes diagnostic of acute myocardial infarction. Each survived; each had normal electrocardiograms before the sting. Though preexistent coronary artery disease can be excluded in neither, the view is favored that acute myocardial infarction in each was caused by deficient coronary perfusion secondary to anaphylactic shock induced by the wasp stings. An intriguing case was just recently reported58 of a 62-year-old man with previous angina who developed pulmonary edema but no chest pain following wasp sting and went on to show rapidly reversed electrocardiographic changes attributable to subendocardial ischemia or infarction. In a sense, this sequence fills the gap as an intermediate phase between the normal and the two individuals described here who developed pain after anaphylactic shock, then proceeded, perhaps through this phase, to develop transmural infarction.
 ...
PMID:Acute myocardial infarction following wasp sting. Report of two cases and critical survey of the literature. 125 36

Eight men, 45 to 50 years of age, with mild stable angina pectoris, participated in a graduated exercise program. Coronary arteriography, left ventriculography, left ventricular hemodynamics at rest and during supine leg exercise, treadmill testing with electrocardiographic monitoring, and measurement of oxygen uptake were obtained before and 1 year after the exercise training program. No change was noted in the arteriographic appearance of coronary artery lesions or of collateral circulation. Left ventricular performance, assessed by qualitative left ventriculography and the hemodynamic response of the left ventricle to supine leg exercise, was unchanged after the training program. Oxygen consumption for a given repetitive work load during treadmill exercise decreased. Two patients with a pretraining exercise ECG positive for ischemia reverted to a normal response after the exercise program. All had a decrease in angina, an increase in self-esteem, and a more positive attitude toward their work and their disability.
 ...
PMID:One-year graduated exercise program for men with angina pectoris. Evaluation by physiologic studies and coronary arteriography. 126 94

The effect of heart rate on the amount and distribution of collateral blood flow was determine in open-chested dogs 1 h after coronary artery ligation. Flows to ischemic and nonischemic regions of left ventricle were measured with 7- to 10- mum diam radioactive microspheres during base-line conditions (118 +/- 6 beats/min) and again during atrial pacing at rates 20 and 40% above control (141 +/- 7 and 165 +/- 9 beats/min). During pacing aortic and left atrial pressures and cardiac output did not change significantly, whereas ST segment elevation in epicardial electrograms increased markedly. In nonischemic myocardium, mean flow increased approximately in proportion to the increase in rate, but subepicardial (EPI) flow increased somewhat more than subendocardial (ENDO) flow. In ischemic myocardium, overall flow did not change significantly, but a redistribution from ENDO to EPO was seen. At the faster rate ENDO flow fell 25% (P less than 0.02), EPI flow increased slightly, and ENDO/EPI fell in 8/9 animals (mean 0.54-0.43, P less than 0.01). The ENDO/EPI maldistribution present in ischemic muscle is thus accentuated by tachycardia; this may account for part of the harmful effect of tachycardia in acute myocardial infarction and may help explain the disproportionate ENDO ischemia seen in angina pectoris.
 ...
PMID:Effect of tachycardia on left ventricular blood flow distribution during coronary occlusion. 126 2


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