O2 Uptake, Exercise & Cor. Circ., Dr. D. Penney
The Heart's Dilemma:
It normally operates with a large A-V O2 difference, ie. high oxygen extraction ratio. Increased oxygen delivery can only be achieved through vasodilation, i.e. increased blood flow. This ability decreases with age and pathology.
Myocardial ischemia is indicated by the following:
Acute change in the T-wave
Acute alteration in height of the ST segment
Release of enzyme (LDH, CPK) into the coronary venous blood
Increased coronary arteriovenous oxygen concentration difference
Higher lactate concentration in the coronary sinus than in a coronary artery
Treatment options: vasodilators, e.g. nitrates
decrease O2 consumption, e.g. beta-blockers.
decrease blood volume e.g. diuretics
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