Coronary blood flow
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چکیده
per tissue mass of all human organs. The resting coronary blood flow is 250 ml min 1 (0.8 ml min 1 g 1 of heart muscle); this represents 5% of cardiac output. Ischaemia results when oxygen demand outstrips supply. Arterial oxygen extraction is 70–80%, compared with 25% for the rest of the body. Therefore, increased oxygen consumption must principally be met by an increase in coronary blood flow, whichmay increase fivefold during exercise. Supply usually closely matches any change in demand. However, an increase in coronary blood flow can independently increase myocardial oxygen consumption (Gregg effect). Thismay be explained by full coronary arteries splinting the heart and increasing the end-diastolic fibre length and contractility.
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تاریخ انتشار 2005