Cardiac Cycle

Front 1

Right side valve (between atria and ventricle)
Left side valve (between atria and ventricle)
What valves exit from ventricles?

Back 1

Tricuspid
Mitral (bicuspid)
Pulmonary = right side (semilunar)
Aortic = left side (semilunar)

Front 2

What principle do the A-V valves operate under?
If pressure is greater in ventricle than atrium, is the valve open?
Does the same principle hold for the pulmonary and aortic valves?

Back 2

Pressure differences
No - close

Yes

Front 3

What does each letter represent?

Back 3

P = atrial depolarization (much smaller mass than ventricle)
QRS = ventricular depolarization
T = ventricular repolarization (occurs more slowly because K channels operate more slowly than the fast sodium channel)

Front 4

Explain the cycle.

Back 4

1. Atrial contracts after the P wave which increases atrial pressure
2. Ventricular pressure increased do to increased ventricular volume
3. Activation of QRS leads to isovolumetric contraction --> ventricular pressure increases because both aortic and mitral valves are closed.
4. After aortic valve opens, ventricular and aortic pressures continue to increase during rapid ejection period (40% of ventricular systole)
5. Peak pressure starts declining during REDUCED rejection period
6. In ventricular systole, atria are ia diastole and are getting filled up with venous return.
7. Ventricular systole ends, aortic pressure exceeds ventricular pressure --> aortic valve closes (ISOVOLUMETRIC RELAXATION)
8. Mitral valve open again when atrial pressure exceeds ventricular pressure.

Front 5

When does ascending aortic blood flow peak?
Is there any retrograde flow? Why?

Back 5

At the end of rapid ejection
For a fraction of a second due to aortic valve closure.

Front 6

When does ventricular volume decline rapidly? When does it increase rapidly?

When does slower filling occur?

Back 6

Rapid ejection phase
Rapid ventricular filling phase

Reduced ejection and filling period (diastasis)

Front 7

What are the first hear sounds heard?
Are they split?

Back 7

Closure of mitral and tricuspid valves
No = occur close together and heard in vibrations set in motion.

Front 8

What are the second heart sounds heard?
What is the difference between this and the first sounds?
Can it be split under physiological conditions?

Back 8

Closure of the aortic and pulmonary valves
Shorter and higher in frequency
Yes = deep breathing
S3 vibrations from filling of ventricles in diastole (not usually heard)

Front 9

What is associated with hearing an S3?
S4?

Back 9

S3 = ventricles fill early in dilation = cardiac disease associated with ventricular overload due to heart failure or valve problems
S4 = atrial contraction association, stiffened ventricle causes vibrations (ATRIAL GALLOP).

Front 10

Describe the first heart sound.

Back 10

FIRST HEART SOUND IS GENERATED BY OSCILLATION OF BLOOD AND VIBRATION IN VENTRICLES, FOLLOWING CLOSURE OF A-V VALVES. IT IS LOWER PITCHED, MORE INTENSE AND LONGER THAN THE SECOND SOUND

Front 11

Describe the second heart soung?

Back 11

SECOND HEART SOUND IS GENERATED BY OSCILLATION OF BLOOD IN AORTA AND PULMONARY ARTERY, FOLLOWING CLOSURE OF AORTIC AND PULMONIC VALVES

Front 12

Describe the third heart sound.

Back 12

THIRD HEART SOUND OCCURS DURING EARLY DIASTOLE, IT IS LOW IN PITCH AND INTENSITY IN THE NORMAL HEART. HOWEVER, DURING HEART FAILURE IT HAS INCREASED INTENSITY. IT IS GENERATED BY VIBRATION OF BLOOD DURING VENTRICULAR FILLING

Front 13

Describe the fourth heart sound.

Back 13

FOURTH HEART SOUND OCCURS DURING ATRIAL CONTRACTION AND IS LOW IN INTENSITY AND PITCH

Front 14

What is the equation of the work of the heart?

Back 14

Pressure times volume

Front 15

What is the Frank-Starling relationship again?

Back 15

Ventricular contractability is regulated by left ventricular volume (end systolic pressure volume relationship = ESPVR) at the end of diastole

EDPVR (end diastolic pressure volume relationship) also shown.

Front 16

Label the parts of the graph.

Back 16

a = ventricular filling
1 = mitral valve closes
b = isovolumetric contraction
2 = afterload; aortic valve opens
c = ventricular ejection
3 = aortic valve closes
d = isovolumetric relaxation
4 = mitral valve opens

Front 17

What is systolic pressure?

Back 17

Peak pressure in the AORTA, not the ventricle.

Front 18

Peak ventricular systolic pressure

Back 18

Systolic pressure in the ventricle

Front 19

Diastolic pressure

Back 19

Minimum pressure in the AORTA, not ventricle

Front 20

End diastolic pressure

Back 20

Pressure in ventricle just before mitral valve closes

Front 21

What is the effect of an increase in preload volume?

Back 21

Increase in preload volume = similar increase in stroke volume

Front 22

Define preload

Back 22

Ventricular pressure at the end of diastole = determined by ventricular and diastolic volume

Front 23

Afterload

Back 23

Ventricular pressure during contraction. Equivalent to diastolic aortic pressure

Front 24

Contractility

Back 24

Strength of ventricular contraction independent or preload or after load = also known as INOTROPY

Front 25

Stroke volume

Back 25

Volume of blood ejected by ventricle during systole. Can be calculated as end diastolic volume minus end systolic volume.

Front 26

Ejection fraction

Back 26

Fraction of end diastolic volume ejected by ventricle during systole
Calculated as stroke volume divided by end diastolic volume
Normal values 55%-75%

Front 27

Cardiac output

Back 27

Volume of blood ejected by ventricle in one minute
Stroke volume * heart rate

Front 28

What is the effect of increasing preload?

Back 28

Stroke volume is increased
Peak systolic pressure increased
End systolic volume remains the same

Arterial pressure = stroke volume*total peripheral resistance, thus there will be an increase in arterial pressure if the heart rate is held constant.

Front 29

What is the effect of decreasing preload?

Back 29

Decreased stroke volume (deacrease pressure) and decreased systolic pressure.

END SYSTOLIC VOLUME IS THE SAME!

Front 30

What is the relationship between afterload and the shortening velocity?

Back 30

Reciprocal relationship
Increase afterload force --> decrease shortening velocity up to the maximal isometric force

Front 31

What is the effect of increasing afterload without changing preload or contractibility (inotropy).

Back 31

Decreased shortening velocity --> increased end systolic volume and thus decreased stroke volume

Can occur if increased aortic pressure is increased by increasing TPR

Aortic pressure = TPR x Cardiac output

Front 32

What is the effect of decreasing afterload?

Back 32

Increased stroke volume

Front 33

What is the effect of increasing contractility (inotropy) while keeping preload and afterload constant?

Back 33

Increased stroke volume and increased systolic pressure (decreases end systolic volume)

Intrinsic activation of the heart = under influence of increased sympathetic activity

Front 34

What is the effect of decreasing contractility (inotropy)?

Back 34

Decreased stroke volume and decreased systolic pressure

Influence of DECREASED sympathetic activity

Front 35

What are the compensatory changes after increasing preload at constant contractility?

Back 35

Increase in stroke volume --> increase in afterload --> ESV
Cardiac output = stoke volume x heat rate
Arterial pressure = cardiac output x TPR

Front 36

What does increasing afterload cause at constant contractility?

Back 36

Reduction in stroke volume and increase in end systolic volume --> end diastolic volume increase because increase in systolic volume gets added to the incoming venous return.

Increase in afterload could be from an increase in TPR

Front 37

What the compensatory changes after increasing contractility (inotropy)?

Back 37

Can be caused by an increase in sympathetic activity

Decrease in end systolic volume --> increase stroke volume --> secondary increase in afterload
Secondarily decreased end diastolic volume due to decreased end systolic volume
Afterload will increase due to increased stroke volume

Front 38

What is the effect of aortic stenosis on cardiac events?

Back 38

Systolic murmur due to turbulent flow into aorta

Heard in crescendo decrescendo manner
Associated with high end diastolic volume and low stroke volume/ejection fraction.

Front 39

What is aortic regurgitation associated with?

Back 39

Diastolic murmur due to turbulent retrograde flow aorta into ventricle, high ventricular end diastolic volume, low effective stoke volume, and high pulse pressure, due to lowered diastolic pressure.

Front 40

What does mitral stenosis cause?

Back 40

Increased left artrial pressure
Diastolic murmur due to high velocity of blood flow --> turbulence and murmur

Front 41

What does mitral regurgitation cause?

Back 41

Atrial pressure rises during systole, due to backflow into atria --> systolic murmur due to turbulent back flow.