Cardiac output and contractility

Question 1

Cardiac glycosides are used to treat?

Why?

Answer 1

1) Heart failure

2) It has a positive inotropic effect

Question 2

What is preload?

Answer 2

Left ventricular end diastolic volume

Question 3

The volume at EDV also relates to?

Answer 3

Venous return

Question 4

What is afterload?

Answer 4

1) Aortic pressure

2) Pressure required to eject blood (open aortic valve)

Question 5

The volume of blood ejected by ventricle with each beat is known as?

Answer 5

Stroke volume

Question 6

What is the equation for stroke volume?

What does SV usually equal numerically?

Answer 6

1) SV = EDV - ESV

2) 70 mL

Question 7

What is the equation for Ejection fraction?

What does EF usually equal numerically?

Answer 7

1) EF% = SV / EDV

2) 55%

Question 8

What is the equation for cardiac output?

What does CO usually equal numerically?

Answer 8

1) CO (or Q) = SV x HR

2) 5 L/min

Question 9

What happens as preload increases?

Answer 9

Increases CO and contractility

Question 10

What happens as afterload increases?

Answer 10

Decrease CO

Question 11

What does the heart do to overcome the decrease in CO due to increased afterload?

Answer 11

Increase HR

Question 12

An increased heart rate can be described as?

An increase in contractility can be described as?

Answer 12

1) Positive chronotropic effect

2) Positive inotropic effect

Question 13

What is the positive staircase effect (Bowditch staircase)?

Answer 13

More calcium enters cells leading to increase in contractility

Question 14

Parasympathetic stimulation can have what type of effect?

Answer 14

Negative inotropic effect in atria only

Question 15

Muscarinic receptor activation leads to?

Answer 15

1) Decrease inward Ca2+ current during plateau

2) ACh increases outward K+ current

Question 16

In a ventricular pressure-volume loop, where is preload and afterload?

Answer 16

1) Preload is right bottom of loop (1)

2) Afterload is corner above preload (2)

Question 17

In a ventricular pressure-volume loop, where is the isovolumetric contraction?

Answer 17

Preload to Afterload (1 to 2)

Question 18

At what point in the ventricular pressure-volume loop does the aortic valve open?

Answer 18

Point 2 (afterload)

Question 19

In a ventricular pressure-volume loop, where does ventricular ejection take place?
Where is pressure at max point?

Answer 19

1) Point 2 to 3

2) In between 2 to 3

Question 20

In a ventricular pressure-volume loop, where is the stroke volume?

Answer 20

Across the loop

Question 21

In a ventricular pressure-volume loop, where does isovolumetric relaxation occur?

Answer 21

From 3 to 4

Question 22

In a ventricular pressure-volume loop, what does point 3 represent?

Answer 22

Systole ends and ventricles relax

Question 23

In a ventricular pressure-volume loop, what does point 4 represent?

Answer 23

Tricuspid/mitral valve opens

Question 24

In a ventricular pressure-volume loop, where does ventricular filling take place?

Answer 24

Point 4 to 1

Question 25

What happens when preload is increased by more venous return?

Answer 25

1) Greater EDV | 2) SV increases

Question 26

In a ventricular pressure-volume loop, what happens to the loop when you increase preload?

Answer 26

Loop is wider to the right

Question 27

In a ventricular pressure-volume loop, what happens to the loop when you increase afterload?

Answer 27

Loop is thinner and taller to the right

Question 28

In a ventricular pressure-volume loop, what happens to the loop when you increase contractility?

Answer 28

Loop is wider to the left

Question 29

What factor causes the end systolic pressure volume relation slope to increase?

Answer 29

Increasing contractility

Question 30

The largest percentage of O2 consumption is for cardiac output or pressure work?

Answer 30

Pressure work

Question 31

What ventricle must proportionally work harder despite CO being similar? Why?

Answer 31

1) Left ventricle | 2) Systemic pressure is greater than pulmonary pressure

Question 32

What is the CO equation in regards to the Fick Principle?

Answer 32

O2 consumption / ([O2] pulmonary artery - [O2] pulmonary vein)

Question 33

At equilibrium, CO equals?

Answer 33

Venous return

Question 34

If you increase inotropy and heart rate what happens to afterload? If you decrease both?

Answer 34

1) Decrease afterload | 2) Increase afterload

Question 35

What does the mean circulatory filling pressure (mean systemic pressure) equal when there is no CO and depends entirely on vascular compliance and blood volume?

Answer 35

7 or 8 mm Hg

Question 36

During cardiac failure, what happens to: 1) Inotropy 2) Vascular compliance 3) BLood volume 4) SVR/TPR

Answer 36

1) Decrease 2) Decrease 3) Increased 4) Increased

Question 37

What is the equation for mean arterial pressure?

Answer 37

MAP = CO x TPR

Question 38

As ventricular end diastolic volume increases what happens to ventricular pressure? When is this occurring?

Answer 38

1) Increases | 2) Systole

Question 39

As ventricular end diastolic volume decreases what happens to ventricular pressure? When is this occurring?

Answer 39

1) Decreases | 2) Diastole

Question 40

Decreasing afterload has what effect on the velocity of ventricular contraction?

Answer 40

Increases it