myocardial ischemia
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Introduction
A condition in which oxygen delivery to & waste removal from the myocardium falls below normal levels with oxygen demand exceeding supply. As a consequence, the metabolic machinery of myocardial cells is impaired leading to various degrees of diastolic (relaxation), then systolic (contractile) dysfunction. If not reversed within 30 minutes, myocardial ischemia generally results in myocardial infarction. Ischemia is usually diagnosed indirectly through techniques that demonstrate reduced myocardial blood flow or its consequences on contracting myocardium.
Etiology
- focal or diffuse coronary spasm
- coronary artery plaque instability
- platelet & fibrin thrombi
- abnormal resistance of intramyocardial vessels
- supply-demand mismatch: imbalance between oxygen supply & demand
- severe anemia, hypotension, hypertension, tachycardia
- hypertrophic cardiomyopathy
- severe aortic stenosis
* myocardial ischemia during exercise stress testing due to coronary artery disease[1]
Pathology
- stenosis > 95% to cause ischemia at rest
- factors of myocardial oxygen consumption
- temporal sequence of events
- ischemia
- diastolic dysfunction
- regional wall motion abnormalities
- ECG changes
- pain
- molecular pathology:
- miR-1 is overproduced in ischemic cardiac muscle
Clinical manifestations
Laboratory
Diagnostic procedures
-- see angina pectoris, acute coronary syndrome & myocardial infarction
Complications
Management
More general terms
More specific terms
Additional terms
References
- ↑ 1.0 1.1 Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
Medical Knowledge Self Assessment Program (MKSAP) 20 American College of Physicians, Philadelphia 2025 - ↑ Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 85