Cardiac output is calculated as stroke volume x heart rate. Which choice represents this formula?

Cardiac output is calculated as stroke volume x heart rate. Which choice represents this formula?

• A. Stroke Volume x Heart Rate
• B. End Diastolic Volume x End Systolic Volume
• C. Preload x Afterload
• D. Heart Rate x Stroke Volume

Answer: (A)

Cardiac output is the amount of blood the heart pumps per minute, and it comes from multiplying how much blood is ejected with each beat (stroke volume) by how many beats occur each minute (heart rate). If stroke volume is 70 mL per beat and heart rate is 70 beats per minute, the cardiac output is about 4900 mL/min (roughly 5 L/min). So the standard way to express the formula is stroke volume multiplied by heart rate. Other ideas don’t describe this per-minute output: end diastolic volume times end systolic volume are just chamber volumes and don’t directly yield a per-minute flow. Preload and afterload influence stroke volume but aren’t themselves the formula for cardiac output. Note that heart rate times stroke volume would give the same result due to the commutative property of multiplication, but the conventional representation is stroke volume × heart rate.

Cardiac output is the amount of blood the heart pumps per minute, and it comes from multiplying how much blood is ejected with each beat (stroke volume) by how many beats occur each minute (heart rate). If stroke volume is 70 mL per beat and heart rate is 70 beats per minute, the cardiac output is about 4900 mL/min (roughly 5 L/min). So the standard way to express the formula is stroke volume multiplied by heart rate.

Other ideas don’t describe this per-minute output: end diastolic volume times end systolic volume are just chamber volumes and don’t directly yield a per-minute flow. Preload and afterload influence stroke volume but aren’t themselves the formula for cardiac output. Note that heart rate times stroke volume would give the same result due to the commutative property of multiplication, but the conventional representation is stroke volume × heart rate.