Which factor, when multiplied by heart rate, yields Cardiac Output?

Which factor, when multiplied by heart rate, yields Cardiac Output?

• A. Stroke Volume
• B. End Systolic Volume
• C. Heart Rate
• D. Systemic Vascular Resistance

Answer: (A)

Cardiac Output is the total volume of blood the heart pumps each minute, and it depends on how often the heart beats and how much blood is pushed out with each beat. The amount multiplied by heart rate to get cardiac output is the amount ejected per beat, known as stroke volume. Stroke volume is defined as the end-diastolic volume minus the end-systolic volume, the amount of blood expelled with each contraction. End systolic volume by itself isn’t the multiplier—it’s part of the calculation that gives stroke volume. Systemic vascular resistance reflects afterload and can influence how much blood is ejected, but it isn’t a direct multiplier with heart rate to yield cardiac output. For example, with a heart rate of 75 beats per minute and a stroke volume of 70 mL per beat, cardiac output is 75 × 70 = 5250 mL per minute (about 5.25 L/min).

Cardiac Output is the total volume of blood the heart pumps each minute, and it depends on how often the heart beats and how much blood is pushed out with each beat. The amount multiplied by heart rate to get cardiac output is the amount ejected per beat, known as stroke volume. Stroke volume is defined as the end-diastolic volume minus the end-systolic volume, the amount of blood expelled with each contraction. End systolic volume by itself isn’t the multiplier—it’s part of the calculation that gives stroke volume. Systemic vascular resistance reflects afterload and can influence how much blood is ejected, but it isn’t a direct multiplier with heart rate to yield cardiac output. For example, with a heart rate of 75 beats per minute and a stroke volume of 70 mL per beat, cardiac output is 75 × 70 = 5250 mL per minute (about 5.25 L/min).