Cardiac Cycle

Question 1

What fraction of time does the heart spend in diastole? Systole?

Answer 1

Diastole = 2/3
Systole = 1/3

Question 2

True or false: the cardiac cycle reduces in time in equal proportion to the increase in heart rate

Answer 2

False–not exactly proportional, although they are inversely related

Question 3

Where are the precordial leads positive (toward the outside of the body, or on the inside near the heart)?

Answer 3

Outside, on the body wall

Question 4

What is R wave progression?

Answer 4

The fact that the R wave increases in amplitude as your move through the precordial leads

Question 5

What is corresponding event in the cardiac cycle to depolarization of the SA node?

Answer 5

Blood is returning to the right atrium

Question 6

What is corresponding event in the cardiac cycle to atrial depolarization?

Answer 6

Atrial contraction

Question 7

What is corresponding event in the cardiac cycle to depolarization of the AV node (specifically, the delay here)?

Answer 7

Ventricular filling

Question 8

What is corresponding event in the cardiac cycle to depolarization of the bundle of His and the Purkinje fibers?

Answer 8

Ventricular contraction

Question 9

What is corresponding event in the cardiac cycle to ventricular depolarization?

Answer 9

Blood expulsion to lungs or periphery

Question 10

What are the units for cardiac cycle?

Answer 10

time/beat (inverse of HR, but not proportional)

Question 11

True or false: diastolic periods reduce less proportionally than systole when you increase the heart rate

Answer 11

False–more than proportionally (i.e. as the heart rate goes up, the heart spends a larger amount of time in systole than would be expected if it were a linear relationship)

Question 12

When is the heart perfused, during diastole or systole?

Answer 12

Diastole

Question 13

When does isovolumic contraction occur, in ventricular systole or diastole?

Answer 13

Ventricular systole

Question 14

When does isovolumic relaxation occur, in ventricular systole or diastole?

Answer 14

Ventricular Diastole

Question 15

When does rapid ejection occur, in ventricular systole or diastole?

Answer 15

Ventricular systole

Question 16

When does rapid filling occur, in ventricular systole or diastole?

Answer 16

Ventricular Diastole

Question 17

When does atrial systole occur, in ventricular systole or diastole?

Answer 17

Ventricular Diastole and systole (bridges the two)

Question 18

When does reduced ejection occur, in systole or diastole?

Answer 18

Ventricular systole

Question 19

What are the seven periods of the cardiac cycle?

Answer 19

1. Atrial systole
2. Isovolumic contraction
3. Rapid ejection
4. Reduced ejection
5. Isovolumic relaxation
6. Rapid filling
7. Reduced filling

Question 20

What accounts for the increase in atrial pressure in the isovolumic ventricular contraction phase?

Answer 20

AV valve will bulge back into atrium

Question 21

What accounts for the steady increase in atrial pressure in the rapid and reduced ventricular ejection phases?

Answer 21

Refilling of the atria from the venous system

Question 22

What accounts for the drop in the atrial pressure in the rapid filling phase of the ventricle?

Answer 22

Blood flowing from atria and into the ventricles

Question 23

What is the “a” wave in the atrial pressure curve?

Answer 23

The contraction of the atria

Question 24

What causes the AV valves to close?

Answer 24

Atrial pressure dropping below the ventricular

Question 25

What is the purpose of the chordae tendiae?

Answer 25

Ensure that the AV valves do not fold back into the atria (do NOT pull the valves open as is commonly believed)

Question 26

What is the event that corresponds to the "c" wave of the atrial pressure curve?

Answer 26

The bulging of the AV valves back into the atria

Question 27

What is occurring in the atria as the ventricles contract?

Answer 27

They fill

Question 28

When in the cardiac cycle do the AV valves open (what is the corresponding event in the ventricles)?

Answer 28

Ventricular isometric relaxation

Question 29

What does the "v" point on the atrial pressure curve correspond to?

Answer 29

Opening of the AV valves

Question 30

Pathologic increases in right atrial pressure leads to what physical exam finding?

Answer 30

JVD

Question 31

What relieves the increase in the atrial pressure that is caused by the AV valves bulging back?

Answer 31

Overall contraction of the heart

Question 32

In what phase does the ventricular pressure increase dramatically?

Answer 32

Isovolumic contraction

Question 33

What causes the increase in ventricular pressure during atrial systole?

Answer 33

Movement of blood into the ventricles from the atria

Question 34

What is the "atrial kick"? What effect does this have on ventricular filling?

Answer 34

An expulsion of blood into the ventricle from the atria Fills about another 15-20%

Question 35

True or false: in a normal, healthy individual, the atrial kick does not do much. It utilized more if the heart is under stress

Answer 35

True

Question 36

What causes the isovolumic stage of ventricular contraction to end? What is the next stage?

Answer 36

Opening of the semilunar valves Next stage = repid ejection

Question 37

What does the aorta do to accomodate the rapid rise in pressure?

Answer 37

Balloons out

Question 38

For what fraction of time does the rapid ejection phase last compared to total systolic time?

Answer 38

1/3

Question 39

For what fraction of time does the reduced ejection phase last compared to total systolic time?

Answer 39

2/3

Question 40

What does the end of the ejection phase/ start of the isovolumic relaxation phase correspond to on an EKG?

Answer 40

T wave

Question 41

What causes the reduced ejection phase to end?

Answer 41

Closure of the semilunar valve

Question 42

What causes the end of the isovolumic relaxation phase?

Answer 42

Opening of the AV valve

Question 43

What happens to both the ventricular and atrial pressure in the rapid fillig phase? Why?

Answer 43

Falls, because there is passive distention of the walls

Question 44

What causes the reduced filling phase / increase in pressure in the atria and ventricles?

Answer 44

Active expansion of the walls of the heart

Question 45

What is the only factor that determines valve opening/closure?

Answer 45

Pressure differentials

Question 46

When does the abrupt rise in the aortic pressure curve end (which ventricular phase)?

Answer 46

Start of the rapid ejection phase

Question 47

What is the effect on systolic pressure of the aorta expanding to accommodate the blood its receiving?

Answer 47

Lowers the pressure

Question 48

What is the effect on the the aorta expanding to accommodate the blood its receiving on the flow of blood (once the valves are shut, that is)?

Answer 48

Increases the flow

Question 49

Why don't the semilunar valves close after the ventricular pressure has fallen below aortic pressure?

Answer 49

Momentum of blood

Question 50

What accounts for the dicrotic notch (incisura) of the aortic pressure curve?

Answer 50

Due to the backward pressure wave returning from the periphery

Question 51

What causes the backward pressure wave (P aug on her graph) in the aorta?

Answer 51

The reflection of the pressure wave when it hits the bifurcation

Question 52

What is the first upstroke in pressure in the aorta caused by?

Answer 52

Blood flow from venticle to aorta

Question 53

What is the second upstroke in the pressure in the aorta caused by? (the "first shoulder")

Answer 53

Due to the backward pressure wave returning from the periphery

Question 54

What is the third upstroke in the pressure in the aorta caused by? (the "secondshoulder")

Answer 54

Systolic ejection

Question 55

What are the two major effects of a calcified aorta on aortic pressure? Why? (hint: one answer is obvious, the other has to do with the reflected pressure wave from the bifucation)

Answer 55

Increases greatly, because it cannot accommodate the rapid increase in pressure from the heart, AND the fact the blood flows faster through the calcified aorta down the artery, causing a larger reflected wave

Question 56

What determines the slope (rate) of the aortic pressure drop after systole?

Answer 56

The pressure in the periphery of the body

Question 57

What would happen to the slope of the aortic pressure line if peripheral resistance increased?

Answer 57

Become flatter

Question 58

What are the three events (in order) that occur when the AV valve opens?

Answer 58

Rapid ventricular filling Decreased filling (diastasis) Atrial contraction

Question 59

What happens once the AV valve closes?

Answer 59

isometric contraction

Question 60

What are the two events that occur when the semilunar valves open?

Answer 60

Rapid ventricular ejection | Decreased ventricular ejection

Question 61

What occurs when the semilunar valve closes?

Answer 61

Isometric relaxation

Question 62

When does the opening of the AV valves occur (systole or diastole)?

Answer 62

diastole

Question 63

When does the closing of the AV valves occur (systole or diastole)?

Answer 63

Systole

Question 64

When does the opening of the semilunar valves occur (systole or diastole)?

Answer 64

Systole

Question 65

When does the closing of the semilunar valves occur (systole or diastole)?

Answer 65

Diastole

Question 66

Through which period(s) of the cardiac cycle are the AV valves open? (atrial systole, iso contract, rapid ejec, reduced ejec, iso relax, rapid filling, or reduced filling)

Answer 66

Atrial systole, then rapid and reduced filling

Question 67

Through which period(s) of the cardiac cycle are the semilunar valves open? (atrial systole, iso contract, rapid ejec, reduced ejec, iso relax, rapid filling, or reduced filling)

Answer 67

Rapid ejection and reduced ejection

Question 68

When, in the cardiac cycle, are no valves open? | atrial systole, iso contract, rapid ejec, reduced ejec, iso relax, rapid filling, or reduced filling

Answer 68

Iso contraction and iso relaxation

Question 69

Review all of the things, including the ventricular volume changes during the cardiac cycle.

Answer 69

Don't you dare click 5 yet

Question 70

What is the stroke volume?

Answer 70

The LVEDV - LVESV | left ventricular end diastolic volume - end systolic volume

Question 71

What cardiac event does S1 correspond to?

Answer 71

Closure of the mitral and tricuspid valves

Question 72

What cardiac event does S2 correspond to?

Answer 72

The closure of aortic and pulmonary valves

Question 73

What causes the physiological splitting of S2?

Answer 73

Delayed closure of the pulmonic valve OR | Early closure of the aortic valve

Question 74

Why would the pulmonary valve close late with inspiration (in terms of physiological splitting of S2)?

Answer 74

Greater venous return to the right heart increases the time it takes to expel all of the blood

Question 75

Why would the aortic valve close early with inspiration (in terms of physiological splitting of S2)?

Answer 75

Less blood returns to the left heart, so less time to change the pressure and close the valve

Question 76

If physiological splitting occurs, which event always comes first: closing of the aortic valve, or pulmonary valve?

Answer 76

Aortic before pulmonic

Question 77

When is an "opening snap" heard? What does this correspond to physiologically?

Answer 77

may be heard if the mitral or tricuspid is hard to open (e.g. in mitral stenosis d/t very fibrous, calcified mitral valve)

Question 78

What causes S3?

Answer 78

When the ventricular myocytes reach their maximum passive stretch length, and the chordae tendinae and AV ring are pulled taut by the stretched ventricle.

Question 79

What causes S4?

Answer 79

Pathological increase in ventricular pressure at the end of atrial systole (a stiffer ventricle)

Question 80

What causes a diastolic murmur?

Answer 80

Mitral valve stenosis

Question 81

What can cause a systolic murmur?

Answer 81

Leaflets not closing completely, causing turbulent blood flow through a partially closed valve

Question 82

What could be the causes of paradoxical splitting?

Answer 82

Any pathology that causes an increase in conduction through one ventricle more than another

Question 83

In a LBB, will a split be heard with inspiration or expiration? Why?

Answer 83

Expiration, since LV ia already delayed, and since the split will manifest itself as the pulmonic valve closing before the aorta