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SF III Test 1 > Ventricular Function I > Flashcards

Ventricular Function I Flashcards

1
Q

How is a ventricular pressure-volume loop generated?

A

Plotting left ventricular pressure as a function of left ventricular volume

A single cardiac cycle is represented by one counter-clockwise circuit

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2
Q

What is stroke volume?

A

EDV-ESV

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3
Q

What is the ejection fraction?

A

SV/EDV x 100

Normally greater than 55%

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4
Q

How does ejection fraction change with contractility?

A

Increased contractility increases EF

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5
Q

What does the end diastolic pressure-volume relationship describe?

A

The passive filling curve of the ventricle

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6
Q

What is compliance?

A

Distensibility of an organ

Intrinsic property of the ventricular wall

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7
Q

What is the normal compliance of the heart?

A

Ventricles can accommodate and increasing volume of blood with only a modest increase in pressure

When venous return begins to exceed normal range, the EDPVR curve begins to rise steeply

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8
Q

How does cardiac hypertrophy affect compliance?

A

Increased thickness of the ventricle decreases ventricular compliance

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9
Q

What is the end-systolic pressure-volume relationship?

A

Pressure-volume relationship when the heart is in a contracted state (end of systole)

Index of myocardial contractility

Will shift if the contractile state changes

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10
Q

What three factors affect ventricular performance?

A

Preload

Afterload

Contractility

*These variables are interdependent, a change in one usually affects the other two

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11
Q

What two measurements are good indices of preload?

A

LVEDV and LVEDP

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12
Q

What is the result of an increased preload, assuming the other factors are held constant?

A

Increased stroke volume

Due to greater force of contraction because of increased stretch

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13
Q

What is the result of an increased afterload, assuming the other factors are held constant?

A

Lower stroke volume and higher end-systolic volume

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14
Q

What is the result of an increased preload when only contractility is held constant?

A

The increased stroke volume due to increased preload is less than if afterload wasn’t held constant

Afterload increases, resulting in less blood being ejected

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15
Q

What is the result of an increased afterload when only contractility is held constant?

A

Results in a decreased stroke volume

The extra blood remaining in the heart at the end of systole will increase the stroke volume of the next contraction due to increased preload

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16
Q

What is the result of an increase in contractility?

A

Will cause the slope of the ESPVR to become steeper and shift left

This enables the ventricle to generate more pressure at any given preload

Increased stroke volume

17
Q

What are three ways preload can be expressed?

A

EDV

EDP

right atrial pressure

18
Q

What are two ways ventricular function is expressed?

A

Stroke volume

Cardiac output

19
Q

How does total blood volume affect preload?

A

Increase will increase preload

Decrease will decrease it

E.g. hemorrhage or dehydration

20
Q

What factors affect preload?

A

Total blood volume

Venous tone

Atrial contraction

Intrathoracic pressure

Body position

Skeletal muscle pump

Intrapericardial pressure

21
Q

How does intrathoracic pressure affect preload?

A

Inspiration increases preload

22
Q

How does the skeletal muscle pump affect preload?

A

Skeletal muscles in the extremities moves blood back to the heart

23
Q

What is the relationship between contractility and stroke volume?

A

Increase in cardiac contractility will result in a greater stroke volume at any given end-diastolic volume

24
Q

What are the factors that affect the inotropic state of the heart?

A

Catecholamines and sympathetic stimulation - increase

Myocardial damage - decrease

25
Q

What factors affect afterload?

A

Vascular resistance

Decreased ventricular compliance

SF III Test 1 (27 decks)

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