CORONARY ARTERIES-CARDIAC O 2 CONSUMPTION

SUMMARY

1. Basal cardiac O₂ consumption: 2ml/100g/min (higher than skeletal muscle).

2. Basal cardiac O₂ extraction is high and there cannot be increased much further, so increase in cardiac O₂ demand must be met by increased coronary flow.

3. Myocardial Work (MW) = SV * PA or aortic pressure (which corresponds to afterload).

4. For unknown reasons, increase in PA or aortic pressure generates more MW than increase in SV.

5. Hence, increased afterload generates more MW than increased preload (why angina is more common with AS than AR).

Reference(s)

Barrett, K.E., Barman, S.M., Boitano, S., Brooks, H.L., Weitz, M., Brian Patrick Kearns, Ganong, W.F. and Mcgraw-Hill Education (Firm (2016). Ganong’s review of medical physiology. 25th ed. New York: Mcgraw Hill Education.
Hall, J.E. and Hall, M.E. (2020). Guyton And Hall Textbook Of Medical Physiology. 14th ed. S.L.: Elsevier - Health Science.
West, J.B. and Luks, A.M. (2021). West’s Pulmonary Pathophysiology. Lippincott Williams & Wilkins.