Question

What would be the heart rate of a person if the cardiac output is 5L, blood volume in the ventricles at the end of diastole is 100mL and at the end of ventricular systole is 50 mL?

• A. 125 beats per minute
• B. 50 beats per minute
• C. 75 beats per minute
• D. 100 beats per minute

Answer 1

The correct option is D 100 beats per minute

Cardiac output (CO) is the amount of blood pumped by the heart in one minute.

It is the product of stroke volume (SV) and heart rate (no. of beats per min).

CO = SV X Heart rate

Stroke volume is the volume of blood that is ejected from each ventricle due to the contraction of the ventricles per heartbeat.

Stroke volume = End diastolic volume – End systolic volume

As per the data given,

Stroke volume = 100 – 50
= 50 mL

Therefore, heart rate = Cardiac output / Stroke volume

= 5000 / 50
= 100 beats per minute.