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)

To determine whether myocardial ischemia is accompanied by variation in heart rate and/or blood pressure, ST-segment analysis on Holter-ECG and ambulatory blood pressure monitoring was performed in 78 patients (64 males/14 females) with essential hypertension. Thirteen out of 55 patients (24%) with angiographically proven coronary artery disease (CAD) showed ST-segment depression (ST-D; group A pos). We observed 41 ST-D (1-11 ST-D; median: 2) lasting from 1 min to 70 min 15 s (median: 4 min 42 s) and an average depression of 185 +/- 48 mV. In comparison, in 6 of 23 patients (26%) with a normal angiogram 24 ST-D (1-10; median: 3; group B pos), which showed longer duration (1 min to 109 min 20 s; median: 11 min 10 s) and less depression (137 +/- 47 mV) have been found. 73.3% of all ST-D in group A pos and all in group B pos were preceded by an average increase in heart rate of 13 bpm. Exclusively, 12 episodes of ischemia (29.3%) in patients with CAD and 8 (33.3%) in patients without CAD were accompanied by an increase in blood pressure, which was more distinct in group A pos. Transient myocardial ischemia can be shown in hypertensive heart disease unrelated to CAD. A clear correlation between an increase in blood pressure and ST-D could not be proven.
 ...
PMID:[Blood pressure variability and transient myocardial ischemia in patients with essential hypertension]. 151 10

Transient myocardial ischemia may result from obstruction to flow in the large epicardial coronary arteries or diminished flow reserve due to small vessel disease or left ventricular hypertrophy. In patients with coronary heart disease, calcium blockers have proven to reduce stress induced ischemia in patients with normal left ventricular function and in those with ischemic cardiomyopathy. However, recent studies indicate a need for caution when giving calcium antagonists to patients with postinfarction left ventricular systolic dysfunction. Moreover, calcium antagonists that reduce heart rate (diltiazem) are able as a monotherapy to reduce total ischemic burden. Calcium antagonists that may increase rate (dihydropiridines) have to be combined with beta-blockers to achieve this goal. For 24-h control of ischemia the ischemic threshold should be determined for a differentiated therapy in the individual patient. Is the ischemic threshold of the majority of episodes lower than the exercise threshold, a calcium blocker should work. Angiotensin-converting enzyme (ACE) inhibitors are not effective in stress-induced ischemia, but may reduce total ischemic burden, although this effect is not significant. In patients with left ventricular hypertrophy and/or small vessel disease, calcium blockers and ACE inhibitors are probably effective in regression of left ventricular hypertrophy and vascular hypertrophy. However, it remains to be shown that ischemia is reduced by these drugs.
 ...
PMID:New concepts in ischemia prevention. 172 49

Transient myocardial ischemia is more frequently silent than accompanied by angina. The frequency of ischemia varies markedly from day to day, so that in order to accurately define the total ischemic burden, it may be necessary to quantitate ischemic episodes for periods longer than 24 hours. Therefore, a programmable, digital device was developed for long-term, interactive, ambulatory monitoring of the electrocardiogram, which uses variations in a time-averaged ST level as an indicator of myocardial ischemia. The electrocardiographic signal is digitized at 256 Hz and analyzed by an algorithm. If ST depression is planar or downsloping and persists for more than 40 seconds, and if the ST depression is equal to or more than a user-programmed threshold, the device marks the onset of an ischemic event and times it. The algorithm has been validated by comparison of its analysis of the ST segment to human and computerized analyses of frequency-modulated Holter recordings and stress tests. To assess the feasibility and utility of long-term monitoring, patients with documented coronary artery disease were monitored continuously for 14-day periods. Of 26 patients enrolled, 8 completed a protocol for individualization of anti-ischemic therapy using transdermal nitroglycerin. Over 90% of ischemic episodes in this group of patients, all of whom had had a previous myocardial infarction, were silent. Treatment with 10 mg of transdermal nitroglycerin reduced the number of ischemic episodes by 59% and the duration of ischemia by 60% (p less than 0.001); there was no diminution in the effectiveness of treatment from week 1 to week 2.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Quantitation of transient myocardial ischemia by digital, ambulatory electrocardiography. 312 90

Ambulatory ST-segment monitoring is a relatively new device in the evaluation of myocardial ischemia. The method is unique in allowing us to continuously examine the patient over an extended period of time in a changing environmental milieu. In survivors of acute myocardial infarction the prevalence of ambulatory or transient myocardial ischemia is lower than in patients with chronic, stable coronary artery disease. A greater proportion of ischemic episodes, however, are silent than in other subgroups with ischemic heart disease. Early after the infarction, transient myocardial ischemia exhibits a circadian variation with a peak activity occurring in the late evening hours. Patients with non-Q wave infarction have more transient myocardial ischemia, whereas thrombolytic therapy seems to result in less residual ischemia. Exercise testing is more sensitive than ambulatory monitoring in the detection of postinfarction myocardial ischemia. There appears to be a poor association between transient myocardial ischemia and severe left ventricular dysfunction. Transient myocardial ischemia has been shown to provide prognostic information in different subsets of patients with previous myocardial infarction, but there is considerable disagreement about how this is expressed in terms of cardiac events. The precise role of postinfarction ST-segment monitoring in clinical practice has yet to be established.
 ...
PMID:Transient myocardial ischemia after myocardial infarction. 772 94

This case study describes myocardial ischemia and stunning after the topical application of phenylephrine-soaked pledgets (0.25%) in a 63-year-old female undergoing elective endoscopic sinus surgery. The patient had no previous history of cardiovascular disease or illicit drug use. Transient myocardial ischemia was associated with acute hypertension, chest pain, and S-T segment changes 4 minutes after pledget placement. Angiography revealed normal coronary blood flow and severe left ventricular systolic and diastolic dysfunction. Follow-up echocardiography demonstrated improved left ventricular function within 1 week and total resolution of dysfunction by 4 weeks after ischemia.
 ...
PMID:Myocardial ischemia and stunning induced by topical intranasal phenylephrine pledgets. 943 94

Transient myocardial ischemia and associated changes in the autonomic nervous system may influence heart rate and ventricular repolarization to variable degrees. This study evaluated the effect of dipyridamole (DIP) induced ischemia on the autonomic balance by spectral analysis of RR and QT intervals variability. Patients with coronary artery disease undergoing DIP stress echocardiography were studied. From high resolution ECG recordings, RR and QT interval measurements were performed by a dynamic template-matching algorithm. A time-variant analysis was used to estimate power in the LF (0.05-0.15 Hz) and in the HF (0.15-0.4 Hz) band of RR and QT interval spectra. Patients were grouped in ischemic and nonischemic subgroups based on the echocardiographic detection of wall-motion abnormalities. In patients without ischemia (n = 28), DIP caused a decrease in LF power and an increase in HF power of the RR and QT interval variability, indicating concordant changes of both intervals. In contrast, patients with inducible ischemia (n = 11) showed a decrease in HF power of the RR interval spectra and an increase of HF power of QT interval spectra. Furthermore, LF power was increased for RR but decreased for QT interval spectra. Our study suggests that DIP induced ischemia causes a loss of autonomic coupling between heart rate and ventricular repolarization for sympathetic and parasympathetic activities. This lability in ventricular repolarization may constitute an arrhythmogenic substrate during acute ischemia in patients with coronary artery disease.
 ...
PMID:Autonomic effects of dipyridamole stress testing on frequency distribution of RR and QT interval variability. 982 56

Transient myocardial ischemia during cardiac surgery causes a loss of energy sources, contractile depression, and accumulation of metabolites and H+ ion resulting in intracellular acidosis. The reperfusion following ischemic cardioplegia recovers intracellular pH, activates Na+-H+ exchange and Na+-Ca2+ exchange transports and consequently produces Ca2+ overload, which yields cell death. Among the various Ca2+ entry pathways, the Na+-Ca2+ exchanger is known to play one of the major roles during the ischemia/reperfusion of cardioplegia. Consequently, information on the changes in intracellular Ca2+ activities of human cardiac myocytes via the Na+-Ca2+ exchanger is imperative despite previous measurements of Ca2+ current of human single myocytes. In this study, human single myocytes were isolated from the cardiac tissues obtained during open-heart surgery and intracellular Ca2+ activity was measured with cellular imaging techniques employing fluorescent dyes. We report that the Na+-Ca2+ exchanger of adult cardiac myocytes is more susceptible to hypoxic insult than that of young patients.
 ...
PMID:Hypoxia delays the intracellular Ca2+ clearance by Na+-Ca2+ exchanger in human adult cardiac myocytes. 1145

Circadian rhythms have long been recognized to occur in many biologic phenomena, including secretion of hormones as well as autonomic nervous system. There is increasing evidence that circadian rhythms have been also found in cardiovascular events, for example, myocardial infarction, sudden cardiac death as well as stroke have shown a circadian pattern of the distribution. Transient myocardial ischemia, detected by ambulatory ST segment monitoring, is also unevenly distributed during the day. The pathophysiology and the mechanism underlying these variations are the focus of much investigation, while it is not full understood up to date. Heart rate, blood pressure, neural and humoral vasoactive factors such as plasma norepinephrine levels and renin activity, and probably also contractility are increased in the morning hours, indicating that increase in myocardial oxygen demand contribute importantly to the increased prevalence of ischemia in the morning. Our recent study found that circadian rhythm of ischemic threshold detected by repetitive exercise treadmill tests in patients with chronic coronary artery disease is also apparently associated with levels of plasma ET-1. This information should enable better understanding as well as treatment on patients on circadian variation of cardiovascular events.
 ...
PMID:Circadian variation in myocardial ischemia: the possible mechanisms involving in this phenomenon. 1288 12