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Query: UMLS:C0151744 (myocardial ischemia)
 31,282 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Clinical observations suggest that a prevalent condition for the occurrence of cardiac arrhythmias is the synergistic interaction of several risk factors including digitalis glycosides, myocardial ischemia and psychological stress. However, little research has been directed toward controlled, systematic investigations of such synergistic interaction, particularly with respect to psychological stress and digitalis glycosides. The present research was undertaken to develop an animal model with which to study the behavioral and neurobiological contributions to arrhythmias during psychological stress in the presence of digitalis. The model used the rabbit as the experimental animal, a pavlovian aversive conditioning procedure and ouabain, a digitalis glycoside. Rabbits received pavlovian conditioning trials in which a tone as a conditioned stimulus (CS) was paired with an eyelid shock as an unconditioned stimulus (US). Twenty-four hours later, a retention test was given in which either of two doses of ouabain or saline was given, followed by 20 CS presentations alone. The CS presentations were given every 120 s (+/- 10 s). During ouabain infusion, the CS significantly increased the frequency of arrhythmic episodes compared to pre-CS baseline frequencies. These arrhythmic episodes were invariably preceded by CS-induced bradycardia. Both parasympathetic and sympathetic involvement were suggested in arrhythmogenesis, since the CS-induced increase in arrhythmic episodes was blocked by pretreatment with either atropine methylnitrate or atenolol. Furthermore, electrical stimulation of the amygdaloid central nucleus, an area implicated in the expression of bradycardia to a pavlovian CS in the rabbit produced arrhythmic episodes in the presence of ouabain. These arrhythmic episodes were similar in topography to CS-induced arrhythmias within any one animal and were decreased by atropine methylnitrate pretreatment. Insights into central and peripheral nervous system mechanisms by which psychological stress is capable of evoking cardiac arrhythmias in the presence of ouabain should ultimately lead to more effective treatment strategies for the prevention of these arrhythmias.
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PMID:Neurobehavioral contributions to cardiac arrhythmias during aversive pavlovian conditioning in the rabbit receiving digitalis. 317 Oct 84

This review summarizes briefly the present knowledge on sleep-related factors in ischaemic heart disease. A marked circadian rhythm in the frequency of onset of acute myocardial infarction has been found, but the exact mechanism is not known. The circadian variation is possibly explained by several mechanisms. The best documented is sleep apnoea syndrome, which seems to be a risk factor for ischaemic heart disease and stroke. Stressful REM-sleep seems to be potentially arrhythmogenic in patients with decreased cardiopulmonary function. The role of coronary spasm, increased thrombocyte aggregation and mental stress in sleep disorders is still poorly understood.
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PMID:Cardiovascular stress and sleep. 331 Aug 37

The clinical syndrome of angina pectoris was accurately described over 200 years ago by Sir William Heberden. However, in recent years, we have learned that many episodes of myocardial ischemia occur that are not accompanied by symptoms of angina pectoris. These silent ischemic episodes may be detected either during exercise testing, using electrocardiographic criteria that can be combined with scintigraphic studies evaluating myocardial blood flow (thallium perfusion studies) or left ventricular function (gated blood pool scans). In addition, continuous electrocardiographic (Holter) monitoring can be used for the detection of transient ST-segment changes; these changes on Holter monitoring have been correlated with abnormalities of myocardial perfusion and function, indicating that they represent true ischemic events. Studies have shown that patients with coronary artery disease who have evidence of ongoing ischemia, whether symptomatic or silent, have an increased risk for experiencing subsequent cardiac events than patients without evidence of ischemia. Many studies have demonstrated that ischemia during an exercise study after myocardial infarction identifies patients at high risk for recurrent cardiac events, whether or not the ischemia is associated with angina pectoris. Holter monitoring has allowed for the detection of ischemic events out of hospital in ambulatory patients. Studies in stable angina patients have shown that there are many asymptomatic episodes in this setting, which are often occurring at low heart rates during activities of everyday life, without an apparent significant increase in myocardial oxygen demands, and these episodes may even be precipitated by mental stress.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Association between silent myocardial ischemia and prognosis: insensitivity of angina pectoris as a marker of coronary artery disease activity. 332 68

To assess the causal relation between acute mental stress and myocardial ischemia, we evaluated cardiac function in selected patients during a series of mental tasks (arithmetic, the Stroop color--word task, simulated public speaking, and reading) and compared the responses with those induced by exercise. Thirty-nine patients with coronary artery disease and 12 controls were studied by radionuclide ventriculography. Of the patients with coronary artery disease, 23 (59 percent) had wall-motion abnormalities during periods of mental stress and 14 (36 percent) had a fall in ejection fraction of more than 5 percentage points. Ischemia induced by mental stress was symptomatically "silent" in 19 of the 23 patients with wall-motion abnormalities (83 percent) and occurred at lower heart rates than exercise-induced ischemia (P less than 0.05). In contrast, we observed comparable elevations in arterial pressure during ischemia induced by mental stress and ischemia induced by exercise. A personally relevant, emotionally arousing speaking task induced more frequent and greater regional wall-motion abnormalities than did less specific cognitive tasks causing mental stress (P less than 0.05). The magnitude of cardiac dysfunction induced by the speaking task was similar to that induced by exercise. Personally relevant mental stress may be an important precipitant of myocardial ischemia--often silent--in patients with coronary artery disease. Further examination of the pathophysiologic mechanisms responsible for myocardial ischemia induced by mental stress could have important implications for the treatment of transient myocardial ischemia.
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PMID:Mental stress and the induction of silent myocardial ischemia in patients with coronary artery disease. 335 95

Physical exertion is a well-documented trigger of transient myocardial ischemia in patients with coronary disease. More recently, studies have shown that mental stress may also be a cause of myocardial ischemia. The purpose of this study was to examine the relationship of physical activities and perceived mental states to myocardial ischemia while patients were going about their normal daily activities. Twenty-eight patients with documented coronary artery disease underwent ambulatory monitoring of the electrocardiogram. Physical activity and perceived mental status were recorded by patients in a diary which was then graded according to intensity of the activity. Analyses of the continuous electrocardiographic recordings were done separately from the analysis of the diaries. The time of each episode of ischemia, the duration of each episode in minutes and the number of episodes in each 24-hour period were calculated. A total of 372 episodes of ST-segment depression occurred in 912 hours of monitoring. Ischemic events occurring during usual physical and usual mental activities were most frequent (36%). Twenty-six percent of ischemic episodes occurred during increased physical activity, but usual mental activities. Interestingly, 22% of the ischemic events occurred at high levels of mental stress, but low physical activity. Ten percent of episodes occurred during sleep. Although the majority of events occurred during usual daily activities, when duration of ischemia was normalized for time spent in each category, increasing physical or mental activity was associated with an increasing duration of ischemia per unit (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Frequency of ST-segment depression produced by mental stress in stable angina pectoris from coronary artery disease. 336 82

Measures of the severity of angina pectoris, coronary anatomy, and left ventricular function are widely used to assess prognosis and determine management in patients with ischemic heart disease. However, recent evidence suggests that myocardial ischemia, with or without angina, is also a reliable prognostic sign. Studies using ambulatory ST-segment monitoring of patients with chronic stable angina out of the hospital have shown that the majority of episodes of transient myocardial ischemia are silent and surprisingly prolonged. Most episodes occur without the increase in heart rate noted during physical exertion. Characteristic abnormalities of regional myocardial perfusion have been observed using positron tomography during both painful and painless episodes of ischemia. Among these abnormalities is an absolute reduction in the perfusion to the poststenotic ischemic segment of myocardium. Episodes of ischemia can be induced in the hospital by a number of ordinary daily activities, including mental stress, cold, and cigarette smoking, and they often resemble episodes recorded from patients out of the hospital. These observations suggest that both an increased myocardial demand and a reduction in coronary blood flow may be important in the genesis of ischemia out of the hospital. If prospective studies confirm that myocardial ischemia is damaging, even in the absence of angina, investigation and treatment policies may need to be reevaluated. Results of ongoing clinical studies will show whether control of the total ischemic burden can prevent myocardial damage and improve the prognosis.
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PMID:Character and causes of transient myocardial ischemia during daily life. Implications for treatment of patients with coronary disease. 348 93

Ambulatory outpatient monitoring of patients with angina suggests a different view of myocardial ischemia than is conventionally obtained from in-hospital tests. Multiple episodes of ST segment depression occur, and the majority of these disturbances are not associated with symptoms. Recently, studies of regional myocardial perfusion using the technique of positron emission tomography with rubidium 82 have confirmed the ischemic nature of these silent ST changes. Furthermore, activities of everyday life such as mental stress or cold exposure seem to provoke both symptomatic and asymptomatic ischemia, as judged by ST depression and reduced cation uptake. This report presents an unusual case of silent myocardial ischemia observed during the chewing of food.
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PMID:Silent myocardial ischemia during mastication. 349 14

Episodes of transient myocardial ischemia during daily life were investigated in 30 patients on two separate occasions, by ambulatory Holter ST monitoring. The first occasion was at a time of uncertainty in the patients' lives, when the results of coronary angiography and the need for surgery were to be discussed. The second was at a later date, when there had been time to adjust to the decision-making process. There were 515 episodes of myocardial ischemia of which 174 were associated with pain and 341 were asymptomatic. Silent ischemia was significantly more frequent during the first period of monitoring compared to the second (p less than 0.02). Patients who had more silent ischemia on the first occasion also entered more self reports of "emotional upset" (tension, worry, etc.,) in their diaries compared to the second occasion. The level of urinary cortisol was taken as a measure of uncertainty and worry, and was significantly higher on the first occasion (p less than 0.03). Differences in urinary noradrenaline excretion were taken as a measure of subjective stress. Patients who excreted more noradrenaline on the first compared to the second occasion had significantly more silent ischemia (p less than 0.007) and longer total ischemic time (p less than 0.01). We suggest that psychological stress may exacerbate myocardial ischemia which is frequently painless.
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PMID:Psychological stress and silent myocardial ischemia. 363 Aug 89

The diagnosis of silent myocardial ischemia is increasing as a result of the widespread use of noninvasive screening techniques. Primary physicians and consulting cardiologists are often unsure how to approach patients with this disorder because its natural history is unknown. There is continuing controversy over proper treatment. This uncertainty, combined with the paradox of having serious heart disease without symptoms, often leads to psychological stress in patients and their families. In a pilot study designed to evaluate the psychological impact of the diagnosis of silent myocardial ischemia, 15 patients were studied. In general, patients and spouses were surprised and concerned by the diagnosis, but most felt that their physicians had been supportive in explaining the problem to them. Because patients trusted their physicians, they not only changed their lifestyles markedly in regard to exercise and diet but also underwent medical or surgical treatment as recommended. Public awareness of the disorder was generally believed to be almost nonexistent. This pilot study provides insight into a subgroup of patients with potentially serious psychological problems and the clinical implications for their physicians.
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PMID:Psychological ramifications of silent myocardial ischemia. 377 29

We studied the changes occurred in the electrocardiograms, phonocardiograms, apexocardiograms, carotid pulse tracings and blood pressure in 21 healthy men, range 18 to 45, before and during performing timed mental arithmetics. Besides well-known significant increase in heart rate, systolic blood pressure, differential blood pressure (no significant rise in diastolic blood pressure was observed) several phonocardiographic abnormalities were recorded: a significant increase in amplitude and number of vibrations of the early systolic ejection sound and a prominent fourth sound. In general the preexistent third sound diminished after mental stress. In young subjects--range 18 to 30--the ratio of preejection period versus ejection period was lower after mental stress as hyperkinetic conditions occurred whilst in adults the ejection period shortened. The detected phonocardiographic abnormalities reflected significant changes in contractility and compliance of myocardium and great vessels. These abnormalities may account for some cardiac dysfunction in patients with ischemic heart disease subjected to neuropsychic stress and may be misinterpreted for more severe pathological changes.
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PMID:Phonocardiographic changes induced by neuropsychic stress. 393 69


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