Ischemia

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Related to Myocardial ischemia: myocardial infarction

ischemia

[i′skē·mē·ə]
(medicine)
Localized tissue anemia as a result of obstruction of the blood supply or to vasoconstriction.

Ischemia

 

a local deficiency of blood; insufficient blood in an organ or tissue because of the narrowing or complete occlusion of the lumen of an afferent artery.

Transitory ischemia (like hyperemia) may result from physiological regulation of the blood supply, such as in reflex spasm of an artery caused by a mental factor (fright); the influence of pain, cold, chemical substances (epinephrine, ergotin), and biological stimuli (bacteria, toxins); the obstruction of an artery by a thrombus or embolus; constriction of the lumen of a blood vessel in connection with an atherosclerotic or inflammatory process in the wall; or compression of an artery by a tumor, scar, or foreign body. The aftereffects of ischemia depend on the degree of disruption of the blood flow, the rate of development and duration of the ischemia, the sensitivity of the tissue to oxygen deficiency, and the general condition of the body. Ischemia may end in complete restoration of the structure and function of the affected organ or tissue, but it also may lead to necrosis (infarct). The central nervous system and heart muscle are particularly sensitive to ischemia.

N. R. PALEEV

References in periodicals archive ?
The prototype serotonin 5-HT 1B/1D agonist sumatriptan increases the severity of myocardial ischemia during atrial pacing in dogs with coronary artery stenosis.
The same criteria are used in ESC guidelines for the management of acute MI in patients presenting with ST segment elevation, with a suggestion for patients with a clinical suspicion of ongoing myocardial ischemia and left bundle branch block to be managed in a way similar to STEMI patients [6] (Figure 6).
- Patients with diabetes, older adults, and those with prior heart attack or prior bypass surgery are particularly susceptible to silent myocardial ischemia
In some symptomatic individuals or in cases with reversible myocardial ischemia, beta-blockers and calcium channel blockers can be used in order to reduce ischemic symptoms [6, 7].
And, acute myocardial ischemia is considered as a major factor of acute severe pulmonary arterial hypertension [21] and pulmonary hemodynamics [22], resulting in ALI.
In conditions with short PR interval like sinus tachycardia, the [T.sub.a] wave can blend into the ST segment and cause ST segment depression mimicking myocardial ischemia. The [T.sub.a] wave voltage of an inverted or retrograde P wave is always larger than that of a sinus P wave [3].
Since the first harmonic is associated with the aging process and with the signs and symptoms of myocardial ischemia, the next issue is whether the first harmonic of radial pulse is an independent predictor for SCAD and for adverse cardiac events (ACE).
After 30 min of myocardial ischemia and 2 h after reperfusion, rats were anesthetized using an intraperitoneal injection of 1% sodium pentobarbital (3mL x [kg.sup.-1]), and the left common carotid artery was detached.
The degree of asphyxia determines the severity of cardiac dysfunction as it may be ignorable in mild hypoxia.4 Transitory myocardial ischemia is often seen as a complication of severe asphyxia which may range from tachypnea to cardiogenic shock.9 Severe asphyxia may cause myocardial dysfunction and injury or ischemic myocardial necrosis in both ventricles as a result of under perfusion.10,11 Persistent low cardiac output during the first 48 hours of life in newborns with perinatal asphyxia is associated with a significantly higher mortality.12
Myocardial ischemia results from the reduction of coronary flow to such an extent that supply of oxygen to the myocardium does not meet the oxygen demand of myocardial tissue.
Myocardial ischemia is a major cause of death, leading to a disease for which clinical therapy is extremely deficient worldwide (1).

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