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Physiology 1 > Exam 3: Cardiac Performance > Flashcards

Exam 3: Cardiac Performance Flashcards

1
Q

What is the formula for stroke volume?

A

SV= EDV- ESV

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2
Q

What is the formula for EF?

A

EF= SV/EDV x100

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3
Q

What is the formula for cardiac output?

A

Co= SV x HR

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4
Q

What is the formula for Cardiac index?

A

CI= CO/SA

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5
Q

What is the formula for left ventricular stroke work?

A

LVSW= SV x LVPP

Left ventricular pulse pressure

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6
Q

What are the 4 things that can hinge the shape of he PV loop?

A
  • Preload
  • Afterload
  • HR
  • an contractility
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7
Q

What is preload?

A

The tension in ventricular wall at the end of diastole-How much blood is in the ventricle before contraction

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8
Q

How do you measure preload?

A

Tension cannot be determined, so measure ventricular EDV or ventricular ED pressure

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9
Q

What does preload determine?

A

Resting fiber length

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10
Q

What is the main point of the frank-starling relationship?

A

A EDV increases, ventricle contracts with more force and a greater SV results

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11
Q

If you increase preload, what else increases?

A

EDV and stroke volume. ESV stays the same

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12
Q

What are the factors that determine preload?

A
  • Ventricular filling time
  • Ventricular compliance
  • Filling pressure
  • Contribution of atrial systole to filling
  • Pericardial constraint
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13
Q

How does langendorff heart preparation affect HR, CO, and SV?

A

Heart rate is increased to approximately 150BPM which lowers time for reduced filling phase.
CO is usually not affect since decreased SV is compensated for by increased HR.
CO is adversely affected when HR is above 150-180BPM

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14
Q

How does sympathetic increased in HR affect SV and CO?

A
  • SV preserved due to increased contractility

- CO can increase dramatically

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15
Q

What reduces compliance?

A

Hypertrophy and ischemia

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16
Q

What does a sleep slope on a pressure volume curve imply?

A

Low compliance

17
Q

What affects right venous pressure?

A

Intrathoracic pressure and central venous pressure

18
Q

What affect will decreased intrathoracic pressure or increased central venous pressure have on RV preload and SV?

A

It will increase both RV preload and SV

19
Q

What is the role of the pericardium with respect to EDV?

A
  • Protects against left ventricular volume overload

- Maintains alignment with major vessels

20
Q

What happens if the pericardium is filled with excess fluid?

A

The fluid will exert a hydrostatic pressure on the external surface of the heart that reduces ventricular compliance.
-Lowered compliance reduces EDV and SV, Clinical example is cardiac tamponade

21
Q

What is afterload?

A

Th resistance against which the ventricle contracts

-Arterial pressure, peripheral vascular resistance, arterial wall compliance, viscosity of blood

22
Q

How do you estimate mean arterial pressure?

A

DP (in aorta) + 1/3 Pulse pressure

23
Q

Afterload has an inverse relationship with what two things?

A
  • ventricular muscle shortening (stroke volume)

- Maximum velocity of ejection

24
Q

What are the effects of an increased afterload with a constant EDV?

A
  • Aortic valve opens later and closes sooner
  • Increased ESV
  • Reduction in SV
25
Q

What can increased afterload?

A
  • Aortic stenosis,
  • elevated arterial pressure
  • Elevated PVR
  • Increased blood viscosity
  • Decreased arterial compliance
26
Q

What is contractility?

A

Ability of heart to do work at any given fiber length

-Distinct from changes in EDV and changed in afterload

27
Q

What are factors that may affect myocardial contractility?

A
  • ANS activity
  • Circulating hormones
  • catecholamines increased Ca2+ influx and availability
28
Q

How does SNS stimulation affect contractility?

A
  • NE increases the SV at a given EDV
  • Increases EF
  • Rate of rise and relaxation increased
  • Positive inotropic effect
29
Q

Fiber length is directly proportional to what?

A

EDV

30
Q

What happens to SV when contractility is increased at a given EDV, EDP, and afterload?

A

The ventricle ejects more blood, so increased SV, due to more rapid and forceful emptying

31
Q

The magnitude of ESV is dependent on what two things?

A

Afterload and contractility

32
Q

What is the Treppe, or staircase, effect?

A

Increasing HR causes calcium accumulation which increases contractility (small positive inotropic effect)

33
Q

What is volume work compared to pressure work? Which is increased during exercise?

A

Volume work refers to moving blood (preload) and pressure work is working against afterload.

Volume work increases during exercise

Physiology 1 (6 decks)

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