Inotropes, Antiarrhythmics, B-blockers Flashcards

1
Q

What drug causes side effect- pulmonary fibrosis

A

Amiodarone

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2
Q

Side effect of carvedilol

A

Vasodilation

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3
Q

What drug causes lupus erythematosis

A

procainimide

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4
Q

What precautions should be taken in dosing digoxin

A

fat dogs and dogs with ascites (calculate on lean body weight), dogs with renal disease, cats (half life variable)

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5
Q

How does digoxin function as an antiarrhythmic

A

vagal tone to prolong conduction time and refractory period

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6
Q

What drug class should be used for supraventricular tachyarrhythmias (a. fib)

A

B-blockers

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7
Q

What drug should be used for suppressing atrial tachyarrhythmias, including atrial tachycardia and acute atrial fibrillation (but not chronic)

A

Procainimide

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8
Q

What kind of drug is quinidine

A

1A

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9
Q

What is the MOA of synthetic catecholamines

A

Stimulate B1 adrenoreceptors

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10
Q

What are the side effects of lidocaine

A

CNS signs in cats and horses, GI

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11
Q

Contraindications- procainimide

A

Bradycardia- butless than quinidine

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12
Q

What class of drugs treats SVTs

A

B blockers

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13
Q

MOA of 1C

A

QRS widening via his-purkinje, shortening of AP only in purkinje leading to heterogeneic effects

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14
Q

What is the bioavailability of oral propanolol

A

2-20% due to first pass liver metabolism

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15
Q

Atenolol- type

A

Selective B1 blocker

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16
Q

What is dilatazem

A

Clas IV- Ca blocker

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17
Q

Carvedilol- type

A

Non-selective B-blocker

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18
Q

What drug should be used in patients with systolic myocardial pump failure and atrial fibrillation, DCM

A

Cardiac glycosides (digoxin)

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19
Q

What drug should be used in ventricular tachyarrhythmias from ischemic myopathy

A

Lidocaine

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20
Q

What are the side effects of amiodarone

A

Pulmonary fibrosis, lots of others : CNS, T4, GI

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21
Q

What class is amiodarone

A

Class III with activity from all other classes as well

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22
Q

Effects of amiodarone-

A

Increased refractory period of ALL cardiac tissue

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23
Q

What drug is used most in a.fib in horses

A

Quinidine

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24
Q

Contraindications- quinidine

A

Bradycardia, caution in CHF due to -ino

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25
Q

What drug is an inodilator?

A

Pimobendan

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26
Q

What is the route for pimobendan

A

Oral, but rapid!

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27
Q

Name a calcium sensitizing drug

A

Pimobenden

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28
Q

What drug should be used to decrease ventricular response in a. fib and SVTs

A

Propranolol

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29
Q

What are the toxicities of digoxin

A

Cardiac toxicity when 60-70% of pumps blocked- HR changes CNS signs from effect on CRTZ - vomiting Monitor serum 1 week after starting, 6-8 hours post pill

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30
Q

What condition might carvediol be helpful in

A

CHF

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31
Q

What effect does pimobenden have?

A

calcium sensitizing +ino plus vasodilation “inodilator”

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32
Q

What are the classes of inotropes

A

Cardiac glycosides B-adrenergic agonists Phosphodiesterase inhibitors Calcium sensitizing

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33
Q

Name a cardiac glycoside

A

Digoxin

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34
Q

What should be used in Boxers with RV cardiomyopathy

A

Sotalol

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35
Q

What class of drug is propanolol

A

Non-selective beta blocker

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36
Q

Where are B1 and B2 receptors

A

B1 - cardiac mm. B2- bronchial and vascular

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37
Q

What is the most commonly used class II and its route

A

Atenolol, Iv and po

38
Q

What are the costs of +ino

A

Increased myocardial oxygen consumption leading to ischemia, generation of malignant arrhythmias

39
Q

Describe effects of low and high dose dopamine, name the receptors affected

A

Low- vasodilation (mostly renal) DA receptors High- +ino B1 receptors Very high - vasoconstriction - a-receptors

40
Q

What are the therapeutic targets of arrhythmia drugs

A

Reduce slope of depolarization, reduce Ca influx,

41
Q

MOA- B-blocker

A

Counter sympathetic stimulation, change conduction properties of SA and AV node, decrease automaticity

42
Q

When do DADs occur

A

After the repolarization (phase 4)

43
Q

MOA- phosphodiesterase inhibitors

A

Inhibits cAMP breakdown

44
Q

What species will not respond to lidocaine (name the condition as well)

A

Horses with ventricular tachyarrhythmias

45
Q

Advantage of procainimide

A

Less autonomic effects and less ventricular response as quinidine, less contraindication to bradycardias

46
Q

What do class 1 drugs depend on

A

K concentration - low reduces efficacy, high potentiates

47
Q

Excretion of digoxin

A

Kidneys, unchanged

48
Q

MOA- 1A

A

Inhibit fast Na involved in phase 0, prolong phase 3, depress Na in phase 4- Decreased automaticity

49
Q

Sotalol- type

A

K-channel (class III) with reverse use dependence

50
Q

Result of class I drugs

A

Decrease in phase 0 of the AP, decrease in slope of phase 4

51
Q

Atenolol- condition treated

A

SVTs or a. fib

52
Q

MOA- calcium sensitizing agents

A

Increases affinity of troponin C for Ca during sys/dia to sensitize contractile apparatus to the existing Ca level

53
Q

Esmolol- type

A

Selective B1 B-blocker

54
Q

What drug should be given for dogs with DCM and CHF

A

Pimobendan

55
Q

Why is propranolol still effective at long intervals

A

Despite the fact that it has a 2 hour half life, activity of its metabolites and protein bound nature help it persist

56
Q

What kind of drug is lidocaine

A

1B

57
Q

What is the mechanism of class III

A

K-blockers - decreased K influx at repolarization phase 4 to increase refractory period

58
Q

What is the effect of class 1B

A

Decreased Na of 0, shorten AP- no effect on atrial arrhythmias

59
Q

What is dobutamine

A

Synthetic analog of dopamine

60
Q

Why might a dog on digoxin vomit

A

Toxicity associated with CRTZ stimuation or parasympathomimetic effects

61
Q

What are the relative durations of B blockers

A

A > P > E (atenolol, propranolol, esmolol)

62
Q

What is the route for synthetic catecholamines

A

CRI

63
Q

What is the MOA for cardiac glycosides (name one)

A

Direct stim of vagal nuclei- Inhibition of Na/K ATPase pump - increased intracell Na which gets exchanged for Ca – increased force of contractility (digoxin)

64
Q

What should be used in emergency SVTs

A

Esmolol

65
Q

Advantage of atenolol

A

Less frequent administration needed

66
Q

PKs of amiodarone

A

Moderate absorb orally, slow elim, strong bind to adipose, - effects delayed several weeks even with loading

67
Q

Bblocker effect on AV and SA

A

Decrease AV conduction, decrease SA discharge

68
Q

Interactions- quinidine

A

Digoxin- decreased excretion

69
Q

What is the main effect of dobutamine

A

B1, better for patients with profound pump failure

70
Q

What is a benefit of calcium sensitizing agents

A

Enhance contractility without increasing O2 consumption/work - less chance of arrhythmia development

71
Q

Positive inotropes do what

A

Increase contractility

72
Q

What drug should be used to treat arrhythmias in cats with hyperthyroidism

A

Propranolol

73
Q

What is a contraindication of lidocaine

A

Bradyarrhythmias

74
Q

What kind of drug is procainimide

A

1A

75
Q

Name a synthetic catecholamines

A

Dopamine (endogenous precursor of NE)

76
Q

What type of drug is dobutamine

A

synthetic catecholamine

77
Q

What does inotropy mean

A

Contraction

78
Q

What mechanism is most used to increase contractility

A

Increasing Ca for more binding sites available for actin-myosin interaction

79
Q

Side effect - propranolol

A

Bronchoconstriction, -ino

80
Q

What does amlodipine treat

A

Hypertension via vasodilation

81
Q

When do EADs occur

A

Phase 2 and 3 of action potential

82
Q

What does dilatazem treat

A

SVT via AV node only, rate control in a. fib

83
Q

What condition should mexiletine be used for and with what

A

Venricular arrhythmias with a b-blocker or class III

84
Q

Sotalol- uses

A

Boxers with RV cardiomyopathy, refractory VT, SVTs

85
Q

Propranolol- BBB?

A

Yes

86
Q

What is an advantage of Atenolol

A

Less respiratory side effects

87
Q

Contras- propranolol

A

DCM (potential -ino), bradyarrs, conduction disturbances

88
Q

Side effects- quinidine

A

hypotension, ventricular arrhythmias, -ino, GI, neuro signs, horses: facial edema, laminitis, D and colic

89
Q

What is the action of class III

A

Prolonged QT interval

90
Q

What is the MOA of Class IV

A

Ca blocker- L-type (slow) channels in pacemakers during phase 0, for decreased CA- prolonged refractory period, depolarization

91
Q

What are the classes of antiarrhythmias

A

No Body Kills Cats 1- Na channel blockers 2- Beta blockers 3- K channel blockers 4- Ca channel blockers

92
Q

Decribe re=entry

A

Premature beats due to lack of termination of the rhythm