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951 Block 3 > 9. Positive Inotropic Agents > Flashcards

9. Positive Inotropic Agents Flashcards

1
Q

When might acute HF occur?

A

after MI

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2
Q

Acute HF or chronic HF: peripheral edema

A

chronic

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3
Q

Acute HF or chronic HF: weight gain

A

chronic

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4
Q

Acute HF or chronic HF: cardiomegaly

A

chronic

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5
Q

Acute HF or chronic HF: most severe symptoms

A

acute

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6
Q

What are the positive inotropic agents?

A
  • Digoxin
  • Dopamine
  • Dobutamine
  • Phosphodiesterase inhibitors
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7
Q

What is the MOA of digoxin?

A

inhibits Na/K ATPase which increases the availability of intracellular Ca

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8
Q

What are the therapeutic effects of digoxin?

A

positive inotropic effect due to increased availability of cytostolic Ca during systole

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9
Q

Therapeutic doses of digoxin do not increase HR. (T/F)

A

True

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10
Q

Without HF, _________ signals dominate.

A

parasympathetic

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11
Q

With HF, ________ signals dominate.

A

sympathetic

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12
Q

Therapeutic doses of digoxin __ (↑/↓) SNS activity.

A

decrease ↓

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13
Q

Therapeutic doses of digoxin __ (↑/↓) PNS activity.

A

increase ↑

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14
Q

Digoxin decreases SNS activity by regulating what?

A

baroreceptor sensitivity

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15
Q

How does digoxin increase PNS activity?

A
  • direct stimulation of vagal nuclei in brain

- decreasing conduction velocity of the heart and prolongs refractory period of pacemaker cells

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16
Q

Excessive doses of digoxin produce toxicity by altering _________ ____.

A

peripheral NS

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17
Q

What are the toxic effects of excessive digoxin on the peripheral nervous system?

A
  • ↑ SNS activity

- ↑ PNS activity: bradycardia and heart block

18
Q

How do excessive doses of digoxin affect the heart?

A

Arrhythmias: high intracellular Ca in pacemaker cells leads to ventricular tachycardia or fibrillation

19
Q

What is the antidote to digoxin?

A

digoxin immune therapy: Digibind

20
Q

Dopamine is the endogenous precursor to what?

A

norepinephrine

21
Q

Low doses of dopamine stimulate primarily ___ and ___ receptors.

A

D1 and D2

22
Q

What is the physiologic response to low doses of dopamine?

A

dilation of renal vessels: ↑ GFR = diuresis

23
Q

Positive inotropic effects of dopamine occur at doses of ________.

A

higher doses: 3-10 mcg/kg/min

24
Q

The positive inotropic effects of dopamine are mediated by what?

A

β1 receptors in the heart

25
Q

What occurs at doses of dopamine > 10 mcg/kg/min?

A
  • increased TPR

- excessive increase in HR

26
Q

What adrenergic receptors does dobutamine stimulate?

A

β1, β2, α

27
Q

In the heart, the primary effect of dobutamine is due to stimulation of what receptor?

A

β1

28
Q

At lower doses of dobutamine, there is a minimal increase in HR. (T/F)

A

True

29
Q

In the vasculature, α agonism due to dobutamine is significant and causes ADRs. (T/F)

A

False: a weak α agonist effect is negated by vasodilation from β2 activation

30
Q

Dobutamine does not activate dopaminergic receptors at any dose. (T/F)

A

True

31
Q

What is the MOA of phosphodiesterase inhibitors?

A

inhibits phosphodiesterase type III: intracellular enzyme that breaks down cAMP

32
Q

Increased cAMP levels increase intracellular Ca. (T/F)

A

True

33
Q

What is the effect of increased cAMP on smooth muscle cells?

A

vasodilation

34
Q

Phosphodiesterase inhibitors are much more potent inotropes than adrenergic agents. (T/F)

A

False: weaker inotrope

35
Q

What are the inotropic phosphodiesterase inhibitor agents?

A

Milrinone

36
Q

What is the route of administration of milrinone?

A

IV

37
Q

What is the primary ADR of phosphodiesterase inhibitors?

A

arrhythmias

38
Q

What is the agent currently under investigation to be used as positive inotrope in HF?

A

Levosimendan

39
Q

What is the MOA of levosimendan?

A

sensitizes troponin-C in myofilaments to intracelular Ca

40
Q

How does levosimendan alter intracellular Ca levels?

A

it does not

41
Q

Acute or chronic HF?

Presents as anatomical abnormalities that develop gradually or following survival of cardiac event

A

Chronic HF

42
Q

Acute or chronic HF?

Adaptive mechanisms to improve cardiac performance

A

Chronic HF

951 Block 3 (10 decks)

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