A

Afterload is the force the ventricle must overcome to eject blood; for the left ventricle this force is essentially the pressure already present in the aorta/large arteries. Mean arterial pressure (the average aortic pressure throughout systole) therefore gives the most direct single‐number estimate of afterload, whereas LVEDP reflects preload and TPR integrates both flow and pressure rather than the instantaneous load on the ventricle [Chirinos, 2010, PMID 20733088].