Antidysrhythmic Drugs - Ch. 52 Flashcards

1
Q

What is a dysrhythmia?

A

Any deviation from the normal rate/rhythm of the heart

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2
Q

What is an arrhythmia?

A

β€œno rhythm”

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3
Q

What is Asystole?

A

No heartbeat

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4
Q

What are tachydysrhythmias?

A

Increased heart rate
-More common
-treated with drugs and other stuff

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5
Q

What are bradydysrhythmias?

A

Slowed heart rate
Electrical pacing
-Treated with Atropine

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6
Q

What caused dysrhythmias?

A

Ischemic heart disease
MI
Cardiomyopathy
myocarditis
electrolyte imbalanses (e.g, abnomral K+ level)

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7
Q

What are antidysrythmics?

A

Drugs used for the treatment and prevention in cardiac rate and/or rhythm

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8
Q

Most antidysrythmics do what?

A

Supress abnormal electrical impulse formation or conduction

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9
Q

What produces cardiac electrical activity?

A

SA node cells
AV node cells
Purkinje fibres cells
Ventricular cells

-Electrical activity differs with each cell type

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10
Q

What results in action potential in cardiact muscle?

A

Movement of ions across the cardiac cell membranes

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11
Q

What does action potential cause the contarction of?

A

Myocaridal muscle

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12
Q

In SA and AV node cells what does action potential depend on?

A

Ca2+ influx via calcium channels

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13
Q

In ventricular/atrial cardiac muscle cells how does action potential start?

A

With Na+ influx (depolarization) via sodium channels

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14
Q

In ventricular/atrial cardiac muscle cells how does action potential end?

A

K+ efflex (repolarization) via potassium channels

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15
Q

What are the symptoms of dysrhythmias?

A

Palpitations
Dizziness
Fainting
Dyspnea
or asymptomatic sometimes

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16
Q

What is the HR of someone with supraventricular tachycardia?

A

120-250 beats/min

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17
Q

What are the kinds of supraventricular tachycardia?

A

Paroxysmal
Persistent
Permanent
Atrial flutter
Atrial fibrillation

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18
Q

What is Paroxysmal supraventricular tachycardia?

A

Episodic, starts suddenly and returns to normal within ~24 hours

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19
Q

What is Persistent supraventricular tachycardia?

A

Episodes last longer than 7 days
Usually treatment is needed to return the heart to a normal rhythm

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20
Q

What is Permanent supraventricular tachycardia?

A

dysrhythmia lasts for more than a year despite medications and other treatments

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21
Q

What is the most common supraventricular tachycardia type?

A

Atrial fibrillation

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22
Q

What is Ventricular tachycardia (VT)?

A

problem with ventricular muscle

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23
Q

How long is non-sustained VT?

A

<30sec

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24
Q

How long is sustained VT?

A

> 30sec

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25
Q

What do supraventricular dysrythmias affect?

A

Ventricular contraction rate
-A-V block desireable

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26
Q

What dysrhythmias are more dangerous?

A

Ventricular are more dangerous than supraventricular

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27
Q

How is the large variety of antidysrhythmic drugs classified?

A

Vaughan Williams classification

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28
Q

What can allantidysrhythmics cause?

A

Dysrhythmias
-Create new and/or worsen existing ones

29
Q

How are drugs classified with Vaughan Williams classification?

A

Into Class Ia,b,c, Class II, Class III, Class IV and unclassified

30
Q

What are Class Ia, Ib, Ic antidysrhythmic drugs?

A

Na Channel blockers

31
Q

What are Class II antidysrythmic drugs?

A

beta-blockers

32
Q

What are Class III antidysrythmic drugs?

A

K channel blockers (+ others)

33
Q

What are Class IV antidysrythmic drugs?

A

Calcium channel blockers

34
Q

What are unclassified antidysrythmic drugs?

A

Adenosine, digoxin

35
Q

What do Class I: Na channel blockers do?

A

All block Na channels which slows depolarization

36
Q

Why are Class I: Na channel blockers subdivided?

A

Because they have differing pharmacological effects

37
Q

What Na channel blockers are in Class Ia?

A

Quinidine, procainamide and disopyramide

38
Q

What do Class Ia: Na channel blockers do?

A

-Block Na channels
Slows atrial and ventricular rates
Delay repolarization (Class III acgtion)
Increase the AP duration

39
Q

What are Class Ia: Na channel blockers used for?

A

Acute onset atrial fibrillation
-Premature atrial contractions (PAC)
-Premature ventricula contractions (PVCs)
-Ventricular tachycardia
-Wolff-Parkinson-White syndrome (cause Tachy, atrial fib/flutter)

40
Q

What Na channel blockers are in Class Ib?

A

IV Lidocaine

41
Q

What do Class Ib: Na channel blockers do?

A

-Block Na channels
Accelerate repolarization
Decrease AP duration

42
Q

What are Class Ib: Na channel blockers used for?

A

Ventricular dysrhythmias only
-PVC
-Ventricular tachycardia
-Fibrillation after MI

43
Q

What Na channel blockers are in Class Ic?

A

Flecainide, encainide, propafenone

44
Q

What do Class Ic: Na channel blockers do?

A

-Block Na channels
Little effect on AP duration or repolarization

45
Q

What are Class Ic: Na channel blockers used for?

A

Severe ventricular dysrhythmias
Atrial fibrillation

46
Q

What beta-blockers are in Class II?

A

Metaprolol, esmolol (IV), propanolol, sotalol

47
Q

What do Class II: Beta-blockers do?

A

reduce or block sympathetic nervous system stimulation
-AV block

48
Q

What are Class II: Beta-blockers used for?

A

Myocardial depressents for supraventricular and ventricular dysrhythmias

49
Q

What Potassium channel blockers are in Class III?

A

Amiodarone, dofetilide, sotalol, bretylium

50
Q

What do Class III: Potassium channe blockers do?

A

Prolong repolarization
Prolong cardiac AP, extends refractory period of cells

51
Q

What does Amiodarone also affect?

A

SA node contractility

52
Q

What is Amiodarone?

A

Very effective drug but ~75% have serious adverse effects
-Lung fibrosis, thyroid

53
Q

How long do you need to use Amiodarone to have serious adverse effects (~75%)?

A

6 months

54
Q

What percentage of cases of amiodarone causing adverse effects are fatal?

A

10%

55
Q

What is Amiodarone used for?

A

Ventricular tachycardia
Ventricular fibrillation
Atrial fibrillation
Atrial flutter
-resistant to other drugs
Sustained ventricular tachycardia

56
Q

What do Class IV: Calcium Channel Blockers do?

A

Inhibit Ca entry into the cell (Cardio-active)
Act on AV node which reduces conduction velocity
-AV block

57
Q

What Calcium channel blockers are in Class IV?

A

Diltiazem, verapamil

58
Q

What are Class IV: Ca channel blockers used for?

A

Proxysmal (periodic attack) SVT
Rate control for atrial fib and flutter
NOT for ventricular dysrythmias

59
Q

What do Unclassified antidysrythmics do (Digoxin and adenosine)?

A

Decrease AV conduction and SA node automaticity

60
Q

What does digoxin do?

A

AV block
Slows heartrate

61
Q

What does adenosine ddo?

A

Slows conduction through AV node (AV block)

62
Q

What is Adenosine used for?

A

Convert paroxysmal supraventricular tachycardia to sinus rhythm

63
Q

Describe the hald life of adenosine?

A

Short
10-20 sec

64
Q

What is the only way adenosine is administered?

A

Fast IV push

65
Q

What may adenosine cause?

A

Asytole for a few seconds

66
Q

What should the client know to notify a HCP about when taking antidysrhythmics?

A

Worsening dysrythmia
Shortness of breath
Edema
Dizziness
Syncope
Signs of toxicity

67
Q

What should clients taking Beta-blockers or digoxin be taught to how to do?

A

How to take their own radial pulse for 1 full minute
-Notify physician if pulse is less than 60bpm before taking next dose

68
Q

What therapeutic response should the nurse monitor for?

A

Decrease BP in hypertensive clients
Decreased edema
Regular pulse rate
Pulse rate without major irregularities
Improved cardiac output