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A&P II (Spring 2025) > [Exam 1] Lecture 4: Medication Effects on CO/VR Curves, Valve Dysfunction > Flashcards

[Exam 1] Lecture 4: Medication Effects on CO/VR Curves, Valve Dysfunction Flashcards

1
Q

What is a mixed vasodilator?

A

A drug that dilates both veins and arteries in the systemic circulation.

An example is sodium nitroprusside, a nitric oxide donor.

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2
Q

What effect does sodium nitroprusside have on systemic filling pressure?

A

It drops the systemic filling pressure and reduces resistance to venous return.

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3
Q

What is the primary action of nitroglycerin?

A

It primarily relaxes the veins more than the arteries, reducing preload.

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4
Q

True or False: Hydralazine is an arterial vasodilator.

A

True.

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5
Q

What is the mechanism of action for hydralazine?

A

The mechanism of action is completely unknown.

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6
Q

What is phenylephrine classified as?

A

A mixed vasoconstrictor that constricts both veins and arteries.

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7
Q

What happens to right atrial pressure during an MI?

A

It elevates due to the heart struggling to pump out blood.

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8
Q

What compensatory mechanisms occur after an MI?

A

Increased venous tone and increased sympathetic activity.

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9
Q

What does increased venous tone do in the context of heart failure?

A

It shifts venous return profiles to higher filling pressures.

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10
Q

What role do catecholamines play after an MI?

A

They increase heart rate and contractility to improve cardiac output.

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11
Q

What happens to sympathetic activity as fluid is retained post-MI?

A

Sympathetic activity typically decreases as blood volume expands.

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12
Q

What is a potential consequence of high sympathetic activity at the heart?

A

It predisposes patients to arrhythmias.

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13
Q

Fill in the blank: High right atrial pressure is typically a sign of _______.

A

[heart failure or fluid retention].

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14
Q

What does the body do to compensate for cardiac failure?

A

Reduces venous compliance and increases systemic vascular resistance (SVR).

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15
Q

What is the significance of maintaining a higher filling pressure in volume-dependent patients?

A

It is crucial for the heart to pump effectively.

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16
Q

Describe the shape of the cardiac output curve in a failing heart.

A

It is abnormal, indicating compromised heart function.

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17
Q

What happens to the circulatory system when a person stands up?

A

The central nervous system tightens blood vessels to prevent passing out.

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18
Q

What is one reason why catecholamines are reduced over time post-MI?

A

Fluid retention allows for a decrease in catecholamine levels.

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19
Q

What is the primary compensation mechanism for cardiac failure related to venous compliance?

A

Reducing Venous Compliance (¯Cv)

This mechanism involves tightening the veins to shift filling pressure towards higher levels.

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20
Q

How does the body compensate for cardiac failure by affecting systemic vascular resistance?

A

Increasing SVR (­ SVR)

This leads to a reduction in the slope of the venous return curve, making it more difficult to return blood to the heart.

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21
Q

What is the effect of increasing blood volume in the context of cardiac failure?

A

Increase Volume (­Vol)

This volume expansion is part of the body’s compensation mechanisms during cardiac failure.

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22
Q

What happens to right atrial pressure (PRA) during cardiac failure?

A

It increases, potentially around 7 mmHg

This is due to high filling pressures and the heart’s struggle to pump out blood.

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23
Q

What is the minimum cardiac output required to maintain life?

A

Approximately five liters per minute

This is essential for adequate oxygen and nutrient delivery to tissues.

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24
Q

What is the definition of preload?

A

Preload is a pressure

It refers to the pressures available to fill the heart with blood, typically measured in mmHg.

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25
Q

What does an elevated preload indicate?

A

It should help with filling

Higher filling pressure generally allows for more blood to be accommodated in the heart.

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26
Q

What is afterload?

A

Afterload is the pressure that the heart must pump against

It is essentially the blood pressure outside the aortic valve.

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27
Q

What relationship exists between afterload and heart function?

A

Higher afterload makes it harder for the heart to pump blood out

It increases the time required to open the aortic valve.

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28
Q

What is contractility?

A

A change in stroke volume while preload and afterload are held constant

It indicates the heart’s ability to contract more forcefully.

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29
Q

How does increased preload affect stroke volume?

A

Increased preload leads to increased stroke volume

This is due to enhanced filling and improved cross-bridge alignment.

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30
Q

What is the effect of decreased preload on the heart?

A

It results in less filling and reduced stroke volume

This leads to lower end diastolic volume.

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31
Q

What happens when afterload is increased?

A

The heart must generate more pressure to overcome the higher pressure in the aorta

This prolongs the contraction phase before the aortic valve opens.

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32
Q

Fill in the blank: Preload is the pressure at the end of phase ______.

A

1

This is when the heart is filled with blood before contraction.

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33
Q

True or False: Afterload is defined as the peak systolic pressure.

A

False

Afterload is more accurately described as the diastolic blood pressure.

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34
Q

What is the normal diastolic blood pressure, which is considered as afterload?

A

About 80 mmHg

This pressure exists right before the aortic valve opens.

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35
Q

What does a higher contractility indicate in terms of stroke volume?

A

Higher contractility correlates with increased stroke volume

This means less blood remains in the ventricle after ejection.

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36
Q

How does the pressure volume loop change with increased afterload?

A

It shifts the pressure volume loop to a higher pressure

The heart needs to build more internal pressure to open the aortic valve.

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37
Q

What happens to the duration of Phase 2 when afterload is higher than normal?

A

The duration of Phase 2 is probably longer than normal

This occurs because the heart has to build up more pressure to open the valve.

38
Q

What is the relationship between time spent in Phase 2 and Phase 3?

A

If more time is spent in Phase 2, there will be less time available for Phase 3

This affects the ejection phase of the cardiac cycle.

39
Q

How is stroke volume calculated?

A

Stroke volume = end diastolic volume - end systolic volume

40
Q

What happens to stroke volume when there is reduced time spent in Phase 3?

A

Stroke volume is probably going to take a hit

41
Q

What is the normal stroke volume mentioned in the content?

A

Normal stroke volume is 70 CC’s

42
Q

What happens to the aortic valve closure time with high pressure in the aorta?

A

The aortic valve may close earlier than normal

43
Q

If end diastolic volume is normal but stroke volume is lower, what happens to end systolic volume?

A

End systolic volume is higher than normal

44
Q

What is the relationship between heart rate and stroke volume when stroke volume is reduced?

A

Higher heart rate is needed to maintain cardiac output

45
Q

True or False: A lower resting heart rate typically indicates better cardiac health.

A

True

46
Q

What effect does reducing afterload have on the pressure at which the aortic valve closes?

A

It lowers the pressure at which the aortic valve closes

47
Q

What is expected to happen to stroke volume when afterload is reduced?

A

Stroke volume is probably going to go up

48
Q

How does increased contractility affect stroke volume?

A

Increased contractility leads to an increase in stroke volume

49
Q

What happens to end systolic volume when contractility increases?

A

End systolic volume decreases

50
Q

What typically happens to blood pressure with changes in contractility?

A

Increased contractility likely increases blood pressure

51
Q

What is a common consequence of a heart with reduced contractility?

A

Higher end systolic volume compared to normal

52
Q

What does a depressed contractility curve indicate about the heart’s ability to pump?

A

It indicates the heart is struggling to pump out a normal stroke volume

53
Q

What compensatory mechanism occurs if stroke volume is reduced?

A

The body compensates with an elevated heart rate

54
Q

What happens to preload in a patient with heart problems?

A

Preload is significantly increased due to fluid retention

55
Q

What is the most common valve problem by age 50 or 60?

A

Aortic valve stenosis

56
Q

How does aortic stenosis affect ventricular pressures?

A

Higher ventricular pressures are required to eject blood

57
Q

Fill in the blank: If the valve is obstructed, it is harder to put blood through that _______.

A

[stenotic valve]

58
Q

What happens to blood ejection time with a high resistance valve?

A

It reduces the amount of time spent ejecting blood

59
Q

What is the body’s response when the heart struggles to put out a normal volume?

A

The body compensates by retaining fluid

60
Q

What happens to preload when the heart struggles to put out a normal volume on each heartbeat?

A

Preload is significantly increased

The body compensates by retaining fluid, expanding blood volume, and increasing filling pressure.

61
Q

What is a common observation in heart valve problems?

A

Increase in preload, CVP, or right atrial pressure

This is a typical response to various heart valve issues.

62
Q

In aortic valve stenosis, what happens to pressures upstream and downstream of the resistance?

A

Upstream pressures are high; downstream pressures are low

This pressure difference affects the overall hemodynamics of the heart.

63
Q

How does aortic stenosis affect pulse pressure?

A

Pulse pressure is narrowed

Typically, in a normal individual, pulse pressure is around 40, but in aortic stenosis, it may drop to about 20.

64
Q

What compensatory mechanism occurs in response to reduced stroke volume due to mitral stenosis?

A

Heart rate increases

The body compensates to maintain cardiac output despite lower stroke volume.

65
Q

What is the impact of a stenotic mitral valve on end diastolic volume?

A

End diastolic volume is lower than normal

This is due to impaired filling from the left atrium to the left ventricle.

66
Q

What happens to pulmonary blood pressure in severe mitral valve stenosis?

A

Pulmonary blood pressure increases

High pulmonary pressures can lead to pulmonary edema and impaired gas exchange.

67
Q

What characterizes a regurgitant or insufficient aortic valve?

A

Blood leaks back into the ventricle

This occurs when the valve fails to close tightly, allowing retrograde blood flow.

68
Q

How does a leaking aortic valve affect end diastolic volume?

A

End diastolic volume becomes higher than normal

The ventricle fills from both the atrium and the aorta.

69
Q

What happens to the shape of the pressure-volume loop in aortic regurgitation?

A

The curve becomes more pronounced in phase four

This reflects increased backward blood flow into the ventricle.

70
Q

What occurs during phase one of the cardiac cycle in aortic regurgitation?

A

The ventricle fills from both the atrium and the leaky aortic valve

This dual filling increases end diastolic volume.

71
Q

What is a potential consequence of prolonged high end diastolic volume in the ventricle?

A

Ventricular walls may thin and stretch

This can lead to worsened valve function and increased insufficiency.

72
Q

In the context of mitral stenosis, what does increased filling pressure lead to?

A

Increased pressure in the lungs

Excessive filling pressure can cause pulmonary edema.

73
Q

Fill in the blank: Aortic valve stenosis typically results in a narrowed _______.

A

pulse pressure

74
Q

True or False: In severe mitral valve stenosis, compensatory mechanisms always improve heart function.

A

False

Eventually, compensatory mechanisms can become detrimental.

75
Q

What should happen in a healthy heart during phase four of the cardiac cycle?

A

Isovolumetric relaxation occurs

In this phase, there should be no change in volume as the ventricle relaxes.

76
Q

What happens to end diastolic volumes when the ventricle fills from two places?

A

End diastolic volumes become really high

This occurs especially if there is a bad valve present.

77
Q

How does a leaky aortic valve affect stroke volume?

A

It requires a larger stroke volume to compensate for backward blood flow

This is due to the need to eject more blood on each beat.

78
Q

What is the consequence of chronic high volumes in the ventricle?

A

The ventricle gets stretched out, leading to further valve problems

This affects both the aortic and mitral valves over time.

79
Q

What does the pressure volume loop indicate about net stroke volume?

A

It does not provide a clear cut number for net forward stroke volume

Estimation is required, especially with a leaky aortic valve.

80
Q

What does an increase in ventricular volume during mitral valve closure indicate?

A

Blood is likely coming from the aorta

This occurs when the mitral valve is closed, and the aortic valve is still closed.

81
Q

At what pressure does the aortic valve typically open in the case of regurgitation?

A

It opens at a lower pressure than normal

This is due to backward blood flow affecting aortic pressure.

82
Q

What occurs to pulse pressure in aortic regurgitation?

A

Pulse pressure is wide due to low diastolic pressure

This is a result of blood leaking in the wrong direction.

83
Q

What is the direction of blood flow in mitral regurgitation?

A

Blood moves from the ventricle back into the atria

This occurs whenever ventricular pressure exceeds atrial pressure.

84
Q

During which phase does pressure in the ventricle begin to ramp up?

A

During Phase two

High ventricular pressure should prevent backward blood flow if the mitral valve is functioning properly.

85
Q

What occurs if the aortic valve is closed while the mitral valve is leaking?

A

Blood moves from the ventricle back into the atria instead of forward

This results in backward movement during ventricular contraction.

86
Q

What happens to the pressure gradient during Phase four of mitral regurgitation?

A

The pressure gradient decreases as the ventricle relaxes

This leads to less backward blood leakage.

87
Q

Describe the shape of the pressure volume loop for mitral regurgitation.

A

It resembles the shape of an ‘M’

This indicates the characteristic backward flow issues.

88
Q

How is aortic regurgitation represented in a pressure volume loop?

A

It appears in the shape of an ‘A’ on its side

This indicates the unique pressure and volume changes associated with this condition.

89
Q

What is a key characteristic of the isovolumetric portion in regurgitant valve issues?

A

It is no longer truly isovolumetric

Backward blood movement alters the expected pressure-volume relationship.

90
Q

What should be monitored in patients with bad valves?

A

The function of other valves and the overall heart condition

This is crucial to prevent further complications from valve dysfunction.

91
Q

What happens if the valves do not fit together properly?

A

It can lead to difficulty in ejecting blood and backward blood movement

Valve fragility and plaque buildup can exacerbate these issues.

A&P II (Spring 2025) (6 decks)

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