Which statement best defines afterload?

Which statement best defines afterload?

• A. End diastolic volume
• B. The pressure the ventricle must overcome to eject blood
• C. Ejection fraction
• D. Cardiac Output

Answer: (D)

Afterload is the pressure the ventricle must overcome to eject blood, determined mainly by aortic pressure and systemic vascular resistance. When afterload is high, the ventricle must generate greater pressure during systole to open the aortic valve, which can reduce stroke volume if the ventricle can’t compensate. This makes the description of afterload as the pressure the ventricle must overcome to eject blood the best fit. End-diastolic volume relates to preload, not afterload; ejection fraction is the proportion of the filled volume that is ejected (a measure of systolic function), not the load against which the ventricle must pump; and cardiac output is the total volume pumped per minute, a product of heart rate and stroke volume.

Afterload is the pressure the ventricle must overcome to eject blood, determined mainly by aortic pressure and systemic vascular resistance. When afterload is high, the ventricle must generate greater pressure during systole to open the aortic valve, which can reduce stroke volume if the ventricle can’t compensate. This makes the description of afterload as the pressure the ventricle must overcome to eject blood the best fit. End-diastolic volume relates to preload, not afterload; ejection fraction is the proportion of the filled volume that is ejected (a measure of systolic function), not the load against which the ventricle must pump; and cardiac output is the total volume pumped per minute, a product of heart rate and stroke volume.