Cardiac output is the volume of blood pumped by the heart per minute and is equal to heart rate multiplied by stroke volume. Cardiac output can be expressed in three ways: stroke volume, minute volume, or cardiac index. Minute volume and cardiac output refer to the same thing in clinical practice. Stroke volume is the volume of blood pumped out of the left ventricle per contraction. Ejection fraction is the percentage of blood ejected from the ventricles during each contraction, normally 60-65%. Cardiac reserve is the maximum increase in cardiac output above normal levels, important for conditions like exercise.

1. CARDIAC OUTPUT

2. Cardiac output is the product of heart rate (HR) and stroke
volume (SV) and is measured in liters per minute. HR is most
commonly defined as the number of times the heart beats in
one minute. SV is the volume of blood ejected during
ventricular contraction or for each stroke of the heart.
• Usually, cardiac output is expressed in three ways:
• 1. Stroke volume
• 2. Minute volume
• 3. Cardiac index.
• However, in routine clinical practice, cardiac output refers to
minute volume.

6. Stroke volume
he definition of stroke volume is the volume of blood pumped out of
the left ventricle of the heart during each systolic cardiac contraction.

9. Minute volume = cardiac output

12. EJECTION FRACTION
Ejection fraction is the fraction of end diastolic
volume that is ejected out by each ventricle. Normal
ejection fraction is 60% to 65%.

13. CARDIAC RESERVE
Cardiac reserve is the maximum amount of blood that
can be pumped out by heart above the normal value.
Cardiac reserve plays an important role in increasing
the cardiac output during the conditions like exercise.
In a normal young healthy adult, the cardiac reserve is
300% to 400%.
In old age, it is about 200% to 250%.
It increases to 500% to 600% in athletes.
In cardiac diseases, the cardiac reserve is minimum or
nil.

15. anemia

16. • Peripheral resistance.

18. Venous return
Venous return in turn, depends upon five factors:
i. Respiratory pump: Respiratory pump is the respiratory activity that helps the
return of blood, to heart during inspiration. During inspiration, it increases the
diameter of inferior vena cava, resulting in increased venous return.
ii. Muscle pump: Muscle pump is the muscular activity that helps in return of the
blood to heart. During muscular activities, the veins are compressed or squeezed.
Due to the presence of valves in veins, during compression the blood is moved
towards the heart.
iii. Gravity
iv. Venous pressure
v. Sympathetic tone.

19. Peripheral resistance.
• Peripheral vascular resistance (systemic vascular resistance, SVR)
is the resistance in the circulatory system that is used to create
blood pressure, the flow of blood and is also a component of cardiac
function. When blood vessels constrict (vasoconstriction) this leads to
an increase in SVR.