Cardiac Cycle

Question 1

What is the cardiac cycle?

Answer 1

Series of consecutive contractions and relaxations of the heart, to ensure a continuous flow of blood & circulation around the body.

Question 2

What is Ventricular diastole?

Answer 2

Diastole: Ventricular relaxation during which the ventricles fill with blood. Preload attributed to isometric contractions and stretching of an intracellular network of the cardiomyocyte.

Question 3

How many phases are present during diastole?

Answer 3

4 phases

Question 4

How many phases are present during systole?

Answer 4

3 phases

Question 5

What is systole?

Answer 5

Systole: Ventricle contraction generates pressure, ejecting blood into the arteries for both pulmonary and systemic circulation.

Question 6

What is an isovolumetric contraction?

Answer 6

Pressure builds up in ventricles, however ventricles do not expel blood until pressure overcomes afterload.

Question 7

At what point does ventricular ejection proceed?

Answer 7

Pressure generated during isovolumetric contractions exceeds afterload

Question 8

What phases occur after isovolumetric contraction?

Answer 8

Ventricular ejection and relaxation

Question 9

What enables ventricular filling?

Answer 9

Passive filling of blood through pressure gradient into ventricle from atria.
Atrial contraction (Systole)

Question 10

What is End Diastolic volume (EDV)?

Answer 10

Volume of ventricles prior to systole

Question 11

What is End-systolic volume (ESV)?

Answer 11

Volume in the ventricles after slow ejection (end stage of systole)

Question 12

What is stroke volume?

Answer 12

The volume of blood expelled from the left ventricle during ventricular systole
EDV-ESV

Question 13

What is the ejection fraction (EF)?

Answer 13

Proportion of the end diastolic volume that is ejected into systemic circulation during systole.

SV/EDV

Question 14

What does EF illustrate?

Answer 14

The contractility of the heart

Question 15

What is the normal ejection fraction?

Answer 15

52-72%

Question 16

What is the typical EF for patients with heart failure?

Answer 16

35%

Question 17

How does blood passively fill the ventricles?

Answer 17

Prior to atrial systole, the blood passively flows through the atrioventricular orifice through the mitral and tricuspid valve

Question 18

What is the valve between the right atrium and right ventricle?

Answer 18

Tricuspid Valve

Question 19

What is the left atrioventricular valve?

Answer 19

Mitral valve

Question 20

What happens to the pressure during atrial filling (Atrial diastole)?

Answer 20

Pressure of atrium increases

P of atrium > p ventricle

Question 21

How is atrial contraction stimulated?

Answer 21

Waves of excitation from the sinoatrial node

Question 22

How is atrial systole depicted on the ECG?

Answer 22

P wave

Question 23

What is the abnormal heart sound due to valve incompetency?

Answer 23

S4

Question 24

What is S4?

Answer 24

Turbulent blood flow through dysfunctional valve closure.

Question 25

What causes s4?

Answer 25

Pulmonary embolism, Congestive heart failure Tricuspid incompetennce

Question 26

Which valves are closed during isovolumetric contraction?

Answer 26

Atrioventricular and semi lunar valves are closed | pressure is accumulating

Question 27

Describe the pressure gradient during an isovolumetric contraction?

Answer 27

Ventricular pressure > atrial pressure

Question 28

Describe the interval of the isovolumetric contraction?

Answer 28

Interval between the AV valves closing, and the semi-lunar valves opening

Question 29

What signifies ventricular excitation on an ECG?

Answer 29

QRS complex

Question 30

What heart sound is heard during the atrioventricular valve closure?

Answer 30

S1

Question 31

What is S1?

Answer 31

The closure of the atrioventricular valves. (Lub)

Question 32

What phase proceeds isovolumetric contraction?

Answer 32

Ventricular ejection phase

Question 33

What is the ventricular ejection phase?

Answer 33

Period at which the ventricular pressure exceeds aortic and pulmonary pressure (afterload) Semi lunar valves open

Question 34

What type of contraction is associated with the ventricular ejection phase?

Answer 34

Isotonic contraction (Sarcomere shortening)

Question 35

What volume resides post-ventricular ejection?

Answer 35

End-systolic volume | Residual volume in the ventricles

Question 36

What is the C wave?

Answer 36

Atrial pressure caused by the right ventricular contraction *(Pushing tricuspid valve into atrium)

Question 37

What type of electrical activity is demarcated on the ECG during the ventricular ejection phase?

Answer 37

None | No heart sounds, no valves are closing

Question 38

What phase succeeds ventricular ejection?

Answer 38

Reduced ejection

Question 39

What is reduced ejection?

Answer 39

END of ventricular systole. | Blood is ejected from the ventricles at a reducing rate as ventricular pressure decreased with volume reduction

Question 40

What happens after reduced ejection?

Answer 40

Aortic and pulmonary pressure increases, exceeds ventricular pressure, and closes semi-lunar valves

Question 41

How is reduced ejection depicted on an ECG?

Answer 41

T wave

Question 42

Why is a T wave shown during reduced ejection?

Answer 42

Cardiac cells are undergoing repolarisation to resting potential

Question 43

What phase succeeds reduced ejection?

Answer 43

Isovolumetric relaxation

Question 44

What phase does isovolumetric ventricular relaxation belong to?

Answer 44

Diastole

Question 45

What happens during isovolumetric relaxation?

Answer 45

Ventricular muscle relaxes, pressure on blood within the ventricles decrease.

Question 46

What sounds is produced during isovolumetric relaxation?

Answer 46

Dicrotic notch

Question 47

What is the dicrotic notch?

Answer 47

Caused by the rebound pressure against aortic valve as distended aortic wall relaxes./

Question 48

What happens to semi-lunar valves during isovolumetric relaxation?

Answer 48

Semi-lunar valves (Aortic and pulmonary) close to prevent back flow to the ventricles AV valves close

Question 49

Why does the ventricular volume remain unchanged during isovolumetric relaxation?

Answer 49

The atrioventricular valves and semi-lunar valves are closed, thus there is no blood flow exchange between chambers

Question 50

What is the second heart sound attributed to?

Answer 50

Closure of semi-lunar valves

Question 51

What stage succeeds isovolumetric relaxation?

Answer 51

Rapid ventricular filling

Question 52

What occurs during rapid ventricular filling?

Answer 52

Atrial pressure increases (ventricular pressure decreases via relaxation) Generates pressure gradient, Enables blood flow through atrioventricular orifice into the ventricles This increases ventricular volume, simultaneously decreases atrial pressure

Question 53

How does rapid ventricular filling occur?

Answer 53

Filling of ventricles is passive, not due to atrial systole.

Question 54

Why does abnormal S3 occur?

Answer 54

Signifies turbulent ventricular filling, attributed to severe hypertension or mitral incompetence

Question 55

What is s3 referred as to?

Answer 55

Ventricular Galloop

Question 56

How is rapid ventricular filling depicted on an ECG?

Answer 56

Isoelectric ECG between cardiac cycles

Question 57

What cardiac phase succeeds rapid ventricular filling?

Answer 57

Reduced passive filling

Question 58

What are the changes to the ECG during reduced passive filling?

Answer 58

There are no changes to the ECG. | Atrial contraction is redundant

Question 59

What occurs during passive ventricular filling?

Answer 59

Slow filling of ventricles (Diastasis), ventricular volume increases slowly (Reduction in pressure gradient)

Question 60

How do the patterns of pulmonary circulation pressures compare on either side of the heart?

Answer 60

The patterns are identical, however quantitatively, the pressure in the right < left

Question 61

Quantitatively, how does the volume ejected by the ventricles compare?

Answer 61

Identical ejection volumes between left and right ventricles

Question 62

How can pressure changes in the pulmonary artery be detected?

Answer 62

Insertion of catheter with ballooon into the pulmonary artery, inflation of balloon prevents blood flow Distal, pressure system of left atrium measured

Question 63

What is pulmonary artery wedge pressure (PAWP)?

Answer 63

Possible to measure the preload on the left side | PAWP is elevated when there is left atrium or mitral valve dysfunction

Question 64

What happens at Point A of the pressure-volume loop?

Answer 64

Mitral valve closure (increase in ventricular pressure) Isovolumetric contraction (Preload)

Question 65

What occurs between A-B within pressure-volume loops?

Answer 65

Ventricular systole isovolumetric contractions: | Increase in left ventricular pressure, volume remains same

Question 66

What occurs at stage B within pressure-volume loops?

Answer 66

Diastolic blood pressure

Question 67

What occurs between B and C within the pressure-volume loops?

Answer 67

Ejection of blood during isotonic ventricular contraction | Ventricular systole.

Question 68

How is pulse pressure measured on the pressure-volume loops?

Answer 68

Systolic blood pressure - Diastolic blood pressure

Question 69

How is systolic blood pressure measured on a pressure-volume loop?

Answer 69

Peak of the loop

Question 70

What occurs during point C on a pressure-volume loop?

Answer 70

Aortic valve closes (Dub)

Question 71

When does the aortic valve open?

Answer 71

Point B

Question 72

What happens between C and D on a pressure-volume loop?

Answer 72

Isovolumetric relaxation; Left ventricular pressure decreases for the same ventricular volume. AV and semi-lunar valves closed.