Cardiac Function

Question 1

What is pre-load? What is pre-load influenced by?

Answer 1

. End diastolic volume

. Influenced by venous return and filling time (faster heart rate means less time for atria to fill= smaller pre-load)

Question 2

What happens to the stroke volume when the end diastolic volume (pre-load) is increased?

Answer 2

Stroke volume increases because there’s more stretch of the heart wall, which gives a more powerful contraction

Question 3

What effect does digoxin have on cardiac output?

Answer 3

Digoxin increases cardiac output by increasing force of contraction and thus stroke volume (cardiac glycoside, positive inotropic drug)

Question 4

How does an increase in after-load/aortic stiffness affect stroke volume?

Answer 4

Aortic stiffness (afterload) decreases stroke volume at a constant pre-load

Question 5

What is afterload?

Answer 5

Aortic pressure (against which the heart must work to eject during systole)