What is the formula for cardiac output?

What is the formula for cardiac output?

• A. Cardiac output = heart rate x stroke volume
• B. Cardiac output = heart rate + stroke volume
• C. Cardiac output = diastolic pressure / heart rate
• D. Cardiac output = stroke volume / heart rate

Answer: (A)

Cardiac output is the amount of blood the heart pumps each minute, and it depends on two factors: how fast the heart beats (heart rate) and how much blood is ejected with each beat (stroke volume). The correct relationship is CO = HR × SV. Since heart rate is in beats per minute and stroke volume is in milliliters per beat, multiplying gives milliliters per minute, which is the cardiac output. In practice, CO reflects the heart’s ability to perfuse organs and can be influenced by preload, afterload, and contractility. The other options don’t fit because they mix quantities that aren’t used together to define CO: adding heart rate and stroke volume blends two different units and has no meaningful interpretation for CO; diastolic pressure is a pressure measurement and doesn’t directly determine CO; dividing stroke volume by heart rate would not yield a valid measure of cardiac output.

Cardiac output is the amount of blood the heart pumps each minute, and it depends on two factors: how fast the heart beats (heart rate) and how much blood is ejected with each beat (stroke volume). The correct relationship is CO = HR × SV. Since heart rate is in beats per minute and stroke volume is in milliliters per beat, multiplying gives milliliters per minute, which is the cardiac output. In practice, CO reflects the heart’s ability to perfuse organs and can be influenced by preload, afterload, and contractility.

The other options don’t fit because they mix quantities that aren’t used together to define CO: adding heart rate and stroke volume blends two different units and has no meaningful interpretation for CO; diastolic pressure is a pressure measurement and doesn’t directly determine CO; dividing stroke volume by heart rate would not yield a valid measure of cardiac output.