Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0151744 (myocardial ischemia)
 31,282 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Angiographically determined changes in segmental wall motion (SWM) and ejection fraction (EF) are sensitive indices of left ventricular (LV) function. To compare the effects of exercise on LV function, first pass radionuclide angiocardiography was used before and during maximal upright bicycle stress in patients with nonsignificantly stenosed coronary arteries, and in those with greater than 75% stenosis. Gamma camera acquisitions were made in the 30 degree RAO projection using a 20 mCi I.V. bolus of 99mTc-pertechnetate. In the control group (seven normals, one nonsignificant (CAD) the EF significantly increased between rest and exercise (0.65 +/- 0.03 to 0.81 +/- 0.03 (mean +/- SEM), p less than 0.005). In this group SWM measured over the two anterior and two inferoposterior segments uniformly increased. In the 11 patients with a history of angina and significant coronary artery obstruction, the EF did not change in three and significantly decreased in the remaining eight (0.57 +/- 0.04 to 0.45 +/- 0.03, p less than 0.005). In all 11 patients SWM either decreased or did not increase in the areas supplied by the significantly stenosed coronary arteries. Upright maximal stress angiocardiography appears to be well-suited for diagnosing ischemic heart disease and localizing the area of ischemic dysfunction.
 ...
PMID:Effects of maximal exercise stress on left ventricular function in patients with coronary artery disease using first pass radionuclide angiocardiography: a rapid, noninvasive technique for determining ejection fraction and segmental wall motion. 75 25

It is apparent that a variety of factors may be responsible for myocardial ischemia, and even infarction, in the absence of occlusive major vessel coronary disease. In particular, it must be emphasized than angina-like chest pain may well have its origin in myocardial ischemia, even in younger patients with unusual patterns of chest pain but without predisposition to premature CAD. Increasing awareness of disorders such as coronary arterial spasm, functional impairment of subendocardial blood flow and the possible role of variant patterns of anatomic distribution of the coronary arterial tree, will provide a better understanding of their significance as determining or contributing factors in patients with the anginal syndrome.
 ...
PMID:The anginal syndrome without evidence of coronary artery disease. 76 88

In 10 patients without and 20 patients with various degrees of angiographically proven CAD 93 pacing runs were studied. Changes of PAm, of ECG, and of anginal pain serving as parameters of myocardial ischemia were correlated to the rate-pressure-product. In patients without CAD no correlations could be ascertained. In each patient with CAD determination of ischemia was achieved reproducibly. Ischemia threshold is represented by a sharp increase of PAm. Ischemia threshold seems a parameter to be preferred as compared to pain threshold. The extent of CAD (angiographically estimated) correlates well with the pacing test especially when collaterals are taken into account. After NG no substantial improvement of ischemia can be detected: Ischemia threshold before and after NG was reached at same rate pressure in each case. We conclude the atrial pacing test to be an excellent test for the provocation of myocardial ischemia. The test is also useful for estimation of the extent of CAD.
 ...
PMID:Pacing-induced myocardial ischemia in spite of nitroglycerin. Correlations regarding the extent of coronary artery disease. 80 82

To clarify the influence of propranolol-and particularly its heart-rate effects-on myocardial ischemia, coronary hemodynamics and metabolism were studied in 15 patients utilizing a protocol to control heart rate. Ten patients had significant coronary narrowing (CAD) and 5 were normal. Systemic pressure, coronary sinus blood flow (CSBF), left ventricular oxygen utilization (LVVO2), ST Segment depression, and myocardial lactate extraction were measured before and after propranolol (10 mg IV), at rest, during pacing-induced tachycardia stress. Propranolol-related reduction in CSBF and LVVO2 at rest was reversed when heart rate was controlled in both patient groups. Propranolol failed to alter heart-rate threshold, tension-time index (TTI), CSBF, or LVVO2 at angina in the CAD patients. Likewise, ischemic-type ST depression, decreases in lactate extraction, and coronary resistance were unchanged compared to values observed during tachycardia stress before propranolol. In normal coronary patients, propranolol also produced no significant change in LVVO2 or coronary resistance when its heart rate effects were controlled. These data imply that a major coronary and metabolic influence of propranolol relates to changes occurring secondary to its influence on heart rate. Furthermore, this agent's anti-ischemic effect is not prominent during tachycardia stress suggesting that this stress test may be clinically useful in patients taking propranolol.
 ...
PMID:Effects of propranolol on coronary hemodynamic and metabolic responses to tachycardia stress in patients with and without coronary disease. 83 33

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

The clinical implications of isolated late recovery ST depression were tested in patients with scintigraphically defined ischemia (coronary artery disease [CAD], n = 18) compared with patients without ischemia (n = 25). Spontaneous (78.4 versus 12.0%, P < 0.008) and exercise-induced angina (44.4 versus 0%, P < 0.0001) were more frequently seen in patients with CAD. Histories of unstable angina (33.3%), prior myocardial infarction (27.8%), ST elevated angina (22.2%) and significant stenosis in the left anterior descending artery (17 of 18, 94.4%) were almost exclusively seen in the CAD group. There was no significant difference between the two groups in capacity for exercise, maximum deviation of ST level or TV2 amplitude. Balloon angioplasty abolished late recovery ST changes in 63.6% of CAD patients. These results suggest that isolated late recovery ST depression, when accompanied with typical chest pain, may be considered as an indicator of myocardial ischemia, but this phenomenon is difficult to distinguish electrocardiographically.
 ...
PMID:Isolated post exercise delayed ST depression as a sign of severe ischemia: the influence of percutaneous transluminal coronary angioplasty. 128 36

Recent investigations of SMI occurring during daily life have advanced our understanding of the pathophysiology of myocardial ischemia. These contributions have directed our attention away from "chest pain" alone and physical exertion as the central provoking factor toward transient myocardial ischemia and its broader triggers and consequences. Transient myocardial ischemic episodes, the majority of which are silent, are found in a subset of patients with any clinical manifestations of CAD (eg, stable angina, unstable angina, myocardial infarction, and sudden death), as well as in those patients with CAD who are and have been totally asymptomatic. These episodes are an independent predictor of increased risk for future cardiac events. Most medical therapy and revascularization therapies have the potential to prevent or relieve these silent episodes; however, we do not yet know which method is superior in reducing SMI episodes or preventing future cardiac events. Furthermore, the benefit of reducing SMI versus the cost and potential morbidity of these chosen therapies is not known. At least three trials are now underway to examine some of these concerns (Table 2). Focus on pain relief alone does not appear to be an adequate approach to alter outcome in patients with CAD and may prove insufficient to control SMI. Until these issues are resolved, we believe a conservative approach to the management of patients with CAD is warranted. Documentation of ischemia (painful or painless) is essential. Three general principles should be kept in mind. First, the presence of detectable ischemia is of central importance. This information should be used in the overall risk assessment of the patient. Second, the level of concern or aggressiveness of treatment should be based on the risk associated with the ischemic abnormalities documented (Table 3). The exercise stress test is the most useful to begin this process. The detection of ischemic-type ST-segment depression, either silent or painful, at a low workload (eg, less than or equal to 120 beats per minute or less than or equal to 6.5 metabolic equivalents [METS]) implies high risk for adverse outcome. Likewise, these ST-segment changes occurring in leads that reflect multiple coronary artery distribution, of greater than 2 mm in magnitude and persisting for greater than 6 minutes, are all markers for high risk. Thallium redistribution defects occurring at low work loads, in multiple areas, associated with increased lung uptake and enlargement of the cardiac pool all imply high risk.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:Treatment strategies for daily life silent myocardial ischemia: a correlation with potential pathogenic mechanisms. 135 7

Transient episodes of myocardial ischemia can be reliably detected by AEM in patients with known CAD. AEM appears to be particularly useful for patients in whom symptom control has been achieved with conventional antianginal drugs because many of these patients (up to 50%) continue to have residual silent ischemia that would otherwise remain undetected. Despite the lack of symptoms, numerous studies in patients with stable and unstable coronary syndromes have shown that the presence of silent ischemia during AEM is associated with an increased risk of subsequent coronary events and cardiac death. Although Holter monitoring is a practical and reliable tool for prolonged evaluation of myocardial ischemia, its routine use can not be advocated until its clinical role has been clearly defined in the ongoing large prospective studies.
 ...
PMID:Ambulatory electrocardiography evaluation of asymptomatic, unstable, and stable coronary artery disease patients for myocardial ischemia. 150 73

Continuous ECG recording of ST segments can provide important insight into the effects of CAD in patients before, during, and after anesthesia and surgery. The stresses of anesthesia and surgery are particularly threatening to the patient with critical coronary disease and ischemia. ST-segment monitoring is a useful alternative to preoperative stress ECG in patients who are unable to exercise, particularly if radionuclide techniques are not readily available. Continuous ST-segment monitoring provides an additional and unique method of monitoring patients during and after surgery, and on-line analysis of such data provides the anesthesiologist with opportunities to recognize and promptly respond to ischemic episodes. Future studies will determine whether such aggressive strategies will alter the outcome for patients with perioperative myocardial ischemia.
 ...
PMID:Perioperative myocardial ischemia and infarction. Detection of myocardial ischemia using continuous electrocardiography. 157 38

The average annual mortality in unselected patients with chronic stable angina is 4%. Mortality is increased in male patients and in patients who have risk factors such as hypertension, previous MI, or abnormal ECGs. We do not routinely recommend cardiac catheterization in the initial management of patients with stable angina unless the patient exhibits evidence for severe myocardial ischemia on non-invasive testing or has symptoms that are refractory to treatment. In patients who undergo cardiac catheterization, the most important determinant of survival is left ventricular function followed by the number of diseased vessels. Noninvasive testing provides important additional prognostic information to cardiac catheterization data and should be used in the decision to treat a patient medically or surgically. Mortality is increased in patients who have low exercise tolerance, exercise-induced ischemia, or a poor hemodynamic response to exercise. Unstable angina in medically treated patients is associated with a 3% to 5% hospital mortality and 7% to 8% mortality in the first year. The rate of nonfatal MI is about 8% to 10% in the first 2 weeks. We routinely recommend coronary angiography unless patients have had recent cardiac catheterization or there is a major contraindication. Mortality is increased in those who fail to respond to initial therapy, who have severe left ventricular dysfunction, and who have multivessel CAD, particularly left main CAD. The question of whether all patients with unstable angina require coronary angiography for risk stratification and possible revascularization is being addressed in the TIMI III trial.
 ...
PMID:The prognosis in stable and unstable angina. 202 4


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