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Cardiology > 2.4.2 Myocardial Performance > Flashcards

2.4.2 Myocardial Performance Flashcards

1
Q

Peak ventricular systolic pressure?

A

maximal pressure achieved during ejection

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2
Q

What is reduced in ventricular hypertrophy? What is a common cause?

A

Ventricular compliance (increased contractility w/ decreased filling)

Common cause: chronic systemic HTN

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3
Q

What would you expect to be altered in ventricular hypertrophy that isn’t altered by SYM firing?

A

Diastolic filling curve

Both affect the contractility

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4
Q

On Starling’s curve, stroke volume will increase as EDV increases up to a point. Then, the SV will decrease as EDV continues to increase. Why is this?

A

This is due to overstretching which causes the overlap of thick and thin filaments to become suboptimal.

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5
Q

What is the equation for SV?

A

EDV - ESV

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6
Q

Describe how decreased inotropic state would change a P-V loop.

A

Same aortic DP

Same EDV

Decreased contractile force

Decreased SV (increased ESV)

Reduced ejection fraction (EF)

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7
Q

Where do the components of an EKG and heart sounds match up to points on a pressure-volume loop?

A
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8
Q

What is the difference b/t the ionotropic reserve and Starling reserve?

A

Starling reserve: maximal increase in SV that can be achieved by increasing EDV

Inotropic reserve: the extent that increased contractility can raise SV

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9
Q
A

B

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10
Q

How do changes in inotropic state alter the Starling curve?

A

Increased inotropy: upward shift of curve

Decreased inotropy: downward shift of curve

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11
Q

What are some ways that TPR is decreased due to systemic ateriolar dilation (altered afterload)?

A
  1. Vasodilator administration
  2. Anaphylactic shock
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12
Q

What is true about intracellular calcium contrations at all points along a single Starling curve?

A

It is the same at all points

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13
Q

The area within the P-V loop represents what?

A

Stroke work

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14
Q

How can parasympathetic innervation of the heart affect CO?

A

Decrease HR by decreasing # of sodium funny channels

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15
Q
A

B

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16
Q

How can sympathetic innervation of the heart change CO?

A
  1. Increase HR (increase sodium funny channels)
  2. Increase preload (increases SV)
  3. Increase afterload (decreases SV)
  4. Increase inotropic state (increases SV)
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17
Q

Summarize the effects that changes in inotropy, afterload, HR, and venous return can have on the Starling curve.

A
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18
Q

Describe how decreased afterload would affect a P-V loop.

A

Same inotropic state

Same EDV

Decreased aortic DP

Decreased systolic pressure

Increased SV (decreased ESV)

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19
Q

What does inotropic state refer to?

A

The force of contraction (contractility)

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20
Q

What is a third way to alter afterload despite no change in TPR?

A

Aortic stenosis

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21
Q
A

C

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22
Q
A

A

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23
Q

What are the two main determinants of preload?

A
  1. Filling Time (HR)
  2. Rate of venous return (venous tone, blood volume, gravity)
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24
Q

What are some measures or variables related to preload?

A

EDV

Venous return

End-diastolic pressure

25
Q

What is afterload?

A

Defined as ventricular wall tension during ejection. It is the resistance that must be overcome to eject blood.

26
Q

Describe the process in which venous pressure is increased in both types of heart failure (systolic and diastolic dysfunction)

A
27
Q

What are some of the indices of afterload?

A

Aortic diastolic pressure (when aorta opens) or aortic systolic pressure

28
Q

What are the two reasons that ventricular filling is impaired in diastolic dysfunction?

A

Increased stiffness of the ventricular wall

Reduced ventricular relaxation during diastole

29
Q

What are some ways to decrease inotropy? (4)

A
  1. Decrease SYM firing
  2. Beta antagonist
  3. Ca Channel blocker
  4. Heart failure
30
Q

What is preload?

A

Defined as stretch on the myocardial fibers before contraction

Related to ventricular filling

31
Q

What is represented by the isovolumic curve?

A

Maximal pressure that can be developed at any ventricular volume (same shape as the Starling curve)

32
Q

What might be responsible for the shifts from 1 to 3 and 1 to 2 along the starling curve?

A

1 to 3: Increased HR or decreased venous return

1 to 2: Decreased HR or increased venous return

33
Q

What are the three key components seen in a P-V loop due to L ventricular systolic dysfunction?

A

The P0 curve is shifted downwards

Same passive filling curve

Increased EDV

34
Q

Distinguish b/t preload and afterload.

A

Preload: ventricular filling which occurs prior to contraction

Afterload: force the ventricle has to overcome during ejection, so it involves factors after ventricular contraction begins

35
Q

How do skeletal muscle and cardiac muscle differ in regards to their inotropic state?

A

Skeletal muscle: cytosolic Ca++ levels are supramaximal during contraction

Cardiac muscle: cytosolic Ca++ levels are subramaximal for cross-bridge activation (Thus, altering Ca++ levels in contracting myocytes will result in formation of more cross bridges and increased contractile force)

36
Q

What are some ways that TPR is increased due to systemic ateriolar constriction (altered afterload)?

A
  1. Administer a vasocontrictor
  2. Some forms of HTN (chronic)
37
Q

What are two ways that force of contraction is enhanced?

A

Sympathetic nerves and cardiac glycosides (these block Na/K ATPase causing the sodium/calcium exchanger to pump Na out while pumping in Ca causing increased contractility)

38
Q

Describe how increased inotropic state would change a P-V loop.

A

Same aortic DP

Same EDV

Increased contractile force

Increased SV (decreased ESV)

Increased SP

39
Q

If aortic DP was increased (everthing else remains the same), how would the ejection rate change?

A

The ejection rate would decrease b/ there would be a smaller difference in P0 - DP

40
Q

What two curves are used to to contruct a pressure-volume loop?

A

End-systolic pressure volume curve, Po, and Diastolic filling curve

aka isovolumic and filling curves, respectively

41
Q
A

D

42
Q

What differentiates systolic dysfunction from diastolic dysfunction

A

Systolic dysfunction decreases EF compared to normal

43
Q

What is the ventricular end-diastolic pressure?

A

Pressure at the end of filling at the time that the QRS complex occurs

44
Q

Decribe how increased preload would change P-V loop.

A

Same inotropic state

Same aortic diastolic pressure

Increased EDV

Increased systolic pressure

Increased SV

45
Q

Draw out a pressure-volume loop and label its key elements.

A
46
Q

Describe how diastolic dysfunction would alter a P-V loop.

A
47
Q

Where is edema located in each of the forms of heart failure? (R and L)

A

R: edema in the systemic organs

L: pulmonary edema due to increased pulmonary venous pressure

48
Q

Describe how decreased preload would change a P-V loop.

A

Same inotropic state

Same aortic DP

Decreased sytolic pressure

Decreaed EDV

Decreased SV

49
Q

What are some ways to increase inotropy?

A
  1. SYM nerve firing
  2. Beta agonist
  3. Cardiac glycoside
50
Q

What can used to determine the rate of ejection?

A

P0 - Aortic DP

51
Q

Why is looking at a starling curve in terms of SV versus EDV limiting as compared to stroke work versus EDV?

A

In a SV v. EDV curve, increased inotropy cannot be distinguished from decreased afterload.

The stoke work versus EDV curve is unaffected by afterload, so it can distinguish b/t an inotropic change and a change in afterload.

52
Q

Why does contractile force increase at greater preloads?

A

The stretch results in more favorable overlap of thin and thick filaments.

53
Q

What does Starling’s Law of the heart state?

A

Stoke volume increases when preload is increased.

54
Q
A

D

55
Q

Describe how increased afterload would change a P-V loop.

A

Same inotropic state

Same EDV

Increased Aortic DP

Decreased SV (increased end-systolic volume)

56
Q

Describe how ventricular hypertrophy would change a P-V loop.

A

Increase inotropy

Increase aortic DP

Decrease EDV

Increase EDP

57
Q

How do changes in inotrophy shift a Starling curve that is based off stroke work verses EDV?

A

It is the same as looking at SV vs. EDV

58
Q

How do changes in afterload affect the Starling curve?

A

Decreased afterload: Shift Starling curve up (increased SV)

Increased afterload: Shift Starling curve downward (decreased SV)

Cardiology (46 decks)

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