1.1.2 Preload

Question 1

What are the four factors that influence cardiac output?

Answer 1

Stroke volume
Preload
Afterload
Myocardial contractility

Question 2

Define Heart failure.

Answer 2

Heart failure is the failure to maintain normal cardiac output under normal filling pressures.

Question 3

What is the mitral valve?

Answer 3

The valve between the left atrium and left ventricle.

Question 4

What is volume overload?

Answer 4

When a chamber of the heart is too full (overloaded) for it to function efficiently.

Ventricular overload is equivalent to an excessively high preload and is a cause of cardiac failure.

Question 5

What are the causes of cardiac failure?

Answer 5

Mitral valve disease
Patent ductus Arteriosus (PDA)
Septal defects

Question 6

What is the end diastolic volume?

Answer 6

This is the the maximum volume of the heart at the end of diastole.

Question 7

What is the end systolic volume?

Answer 7

This is the volume of blood left in the heart at the end of systole; it is the EDV - SV.

Question 8

Define Preload.

Answer 8

Preload is the degree of stretch in the ventricular myocardium at the end of diastole.

Question 9

3 factors affecting preload

Answer 9

Venous tone
Myocardial compliance
Volume of blood

Question 10

What is starling’s law?

Answer 10

The energy of contraction of a muscle fibre is proportional to the fibre length at rest.

Question 11

What is Dilated cardiac myopathy (DCM)?

Answer 11

When the heart is volume overloaded, stretching the heart muscle and adding in more sarcomeres, this is eccentric hypertrophy.

Question 12

What factors influence the peripheral venous pressure?

Answer 12

Increased activity of sympathetic nerves to veins (contact them)
Skeletal muscle pump
Inspiration
Increased blood volume