Antiarrythmics Flashcards

1
Q

Conduction pathway

A

SA, atria

AV, bundle of his, bundle branches, purkinje, ventricles

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2
Q

Where is SA node located

A

Right atria, posterior wall, by SVC

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3
Q

Where is AV node

A

Septal wall near coronary sinuses

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4
Q

Phase 0

Phase 1

A

Rapid depolarization

Partial repolarization

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5
Q

Phase 2

Phase 3

A

Plateau

Repolarization

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6
Q

Phase 4

Refractory period

A

Pacemaker potential

Phases 1-3

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7
Q

What occurs in phase 0

A

Rapid depolarization, fast na channels open, inward Na movement

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8
Q

What happens phase 1

A

Begin repolarization, na channels close

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9
Q

What happens phase 2

A

Plateau, slow ca ch open, slow inward ca

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10
Q

What happens phase 3

A

Repolarization, ca channels close, k channels open, slow outward k

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11
Q

What happens phase 4

A

Pacemaker potential. Return to RMP

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12
Q

SA node rate controlled by

A

ANS

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13
Q

SNS stim
Receptors
What happens

A

B1.
Inc: catecholamines, hr (chronotropy), automaticity
Facilitation of conduction of AV node

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14
Q

PNS ___
Receptors
What they do

A

Predominates
M2 muscarinic
Decreases HR, inhibits AV conduction, reduced automaticity

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15
Q

Arrhythmias classified by

A

Site of origin (atrial, junctional, ventricular)
Wide or narrow ecg
Rhythm
HR inc or dec

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16
Q

4 mechanisms of arrhythmia production

A

Altered automaticity
Delayed after depolarization
Re entry
Conduction block

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17
Q

Altered automaticity

A

Latent pacemaker cells take over SA node role, escape beats

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18
Q

Delayed after depolarization

A

Normal action potential of cardiac cell triggers abn depolarizations

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19
Q

Re entry

A

Refractory tissue reactivated repeatedly and rapidly d/t unidirectional block, continuous circuit

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20
Q

Conduction block

A

Impulse fail to propagate in nonconducting tissue

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21
Q

Factors underlying cardiac arrhythmias

8

A

Arterial hypoxemia, electrolyte abn, acid base abn, myo ischemia, alt SNS activity, bradycardia, drugs, enlargement/failing ventricle

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22
Q

When arrhythmias require tx

A

Can’t be corrected by removing cause
Hemodynamic compromise
Predisposes to more serious arrhythmias

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23
Q

Non pharm prophylaxis

A

Radio frequency catheter ablation

Implantable defibrillator

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24
Q

Class and phase they tx

Class I drugs

Class II

A

Na channel blockers, phase 0

BB, phase 4

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25
Q

Class and phase tx
Class III
Class IV

A

K ch blockers, phase 1 and 2

Ca ch blockers, phase 2

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26
Q

Class and phase tx

V

A

Unclassified drugs

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27
Q

Effects of class I agents

A

Phase 0 depresses vmax velocity, dec in AP propagation, slows conduction velocity

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28
Q

IA agents
Dissociation
4 effects

A

Intermediate

Decrease: depolarization rate phase 0, decrease conduction velocity. Prolong repolarization phase 3. Inc AP duration

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29
Q

IA drugs 3

A

Quinidine (prototype)
Procainamide
Disopyramide

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30
Q

Disopuramide
Indic
Route
SE

A

Suppresses vent tachyarrythmias. PO. Myocardial depressant, potentiates HF/hypotension. Atropine like effects.

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31
Q

IB agents
Dissociation
How they work

A

Fast na channel block. Alt AP by inhibit na influx, bind to na ch. little effect on max velocity, shortens ap duration and refractory period. Dec automaticity.

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32
Q

IB agents

4

A

Lidocaine (prototype)
Mexiletine
Tocainide
Phenytoin

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33
Q

Lidocaine
Class
Action

A

IB antiarrythmic

Na fast ch blocker

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34
Q

Lidocaine

Indic

A

Acute tx and prevention of v dysrhythmias, immeadiate aftermath of MI. V tach, v fib, pvcs

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35
Q

Lidocaine
Dose
Protein binding

A

1-1.5 mg/kg IV, then 1-4 mg/min gtt, max 3 mg/kg

50% binding

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36
Q

Lidocaine
Metabolism
Slowed by

A

Active metabolite prolongs 1/2t. Impaired by drugs: cimetidine, propranolol, or CHF, MI, liver dysfunc, GA.

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37
Q

Lidocaine
Metab induced by
Elim

A

Barbs, phenytoin, rifampin

10% renal elim

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38
Q

Lidocaine
E 1/2t
Therapeutic plasma level

A

2 hrs

1-5 mcg/ml

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39
Q

Lidocaine

AE

A

Low bp and hr, seizure, drowsy, dizzy, lightheaded, tinnitus, confusion, apnea, myo, cns, and vent depression, sinus arrest, heart block, cv arrest, augment Nm blockade

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40
Q

Phenytoin
Class
Indic

A

IB agent

Suppression of ventricular arrhythmias, assoc w dig toxicity (torsades)

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41
Q

Phenytoin
Give how
What happens in PIV

A

IV, ppt in D5W mix in NS

Pain or thrombosis

42
Q

IC agents

What they do

A

Slow na ch blocker. Doesnt vary in cv cycle. Potent dec depolarization rate phase 0 and conduc rate w inc AP. Inhib thru his/purkinje.

43
Q

IC agents 2

A

Flecainide prototype

Propafenone

44
Q

Flecainide
Indic
Sf
Duration

A

Tachyarrythmias w abn conduction pathways, WPW
Proarrythmic SE
Long acting

45
Q
Propafenone 
Indic 
Properties 
Route 
SE
A

Vent and atrial tachyarrythmias.
Weak BB and ca block. PO.
Proarrythmic SE

46
Q

Class II agents
What they are, phase
How they act

A

BB. Depress phase 4 depolarization, dec SA node discharge. Slows HR and dec myo 02 reqs, good for CAD. Slows AV conduc, prolongs PR. Dec automaticity.

47
Q

Class II

Indications

A

Tx SVT, atrial, and vent arrhythmias (esp post MI and reperfusion). Tx tachyarrythmias assoc w dig toxicity and SVT (afib or flutter)

48
Q

Class II

Prevents binding of what

A

Catecholamines to beta receptors

49
Q

Class II agents

4

A

Propranolol- prototype
Metoprolol
Esmolol
Labetolol- off label use

50
Q

Propranolol
Class
Indic

A

Beta adrenergic agonist, nonselective.

Prevents reoccurrence of supra and ventricular tachyarrythmias ppt by SNS stim

51
Q

Propranolol

Dose

A

1 mg/min (total 3-6 mg) IV or 10-80 mg po

52
Q
Propranolol 
Onset 
Peak 
Duration 
E 1/2
A

2-5 min
10-15 min
3-4 hrs
2-4 hrs

53
Q

Propranolol
Protein binging
Metabolism
Therapeutic level

A

90-95%
Hepatic, weak metabolite
10-30 Ng/ml

54
Q

Propranolol
Cv effects
Caution with

A

Bradycardia and myocardial depression

Reactive a/w disease, hypovolemia, CHF, AV block

55
Q

Metoprolol
Class
Dose

A

B adrenergic antag, selec B1

5 mg IV over 5 min, max dose 15 mg over 20 min

56
Q
Metoprolol 
Onset 
1/2 life 
Metab 
Can be used in
A

2.5 min
1/2 life 3-4 hrs
Liver
Mild CHF

57
Q

Esmolol
Class
Dose

A

Beta adrenergic Antag, b1 selec

0.5 mg/kg iv over 1 min, then 50-300 mcg/kg/min

58
Q

Esmolol
Duration
Effects what w/o effecting what

A

<15 min. Hr w/o dec bp significantly in small doses

59
Q

Esmolol
Metab
No effect on

A

Hydrolyzed by plasma esterases

Not same esterases as cholinesterase, so no effect on sux

60
Q

Class III

Action

A

Prolongs cv depolarization and inc AP duration, lengthens repolarization. Dec proportion of cycle when myo cells excitable, susceptible to triggering event

61
Q

Class iii

Indications

A

Suppressing supra and ventricular arrhythmias. Prophylaxis cv surgery for afib. Preventative for pts posT CV death not candidate for ICD. Controls rhyth afib.

62
Q

Class iii drugs 3

A

Amio- prototype
Dronedarone
Sotalol

63
Q

Amio

Which class

A

III. But has I, II, and IV properties

64
Q

Amio

Blocks what

A

K, na, ca channels. Alpha and beta adrenergic antagonist

65
Q

Amio

Indic

A

Prophylaxis or tx atrial and vent arrhythmias (refractory SVT/VT/VF/AF), 1st line w VT/VF resistant to defibrillation

66
Q

Amio

Dose

A

150-300 mg iv over 2-5 min. Up to 5 mg/kg. Then 1 mg/min x.6 hrs, 0.5 mg/min 18 hrs

67
Q

Amio
E 1/2 t
Metabolism and excretion

A

10-100 days (long)
Hepatic, active metabolite
Biliary and intestinal excretion

68
Q

Amio
Therapeutic level
Protein binding
Vd

A

1-3.5 mcg/ml
Extensive. 96%
Large

69
Q

Amio

AE

A

Pulm toxicity/fibrosis/edema. ARDS. Photosensitive rash, grey/blue skin. Thyroid abn. Corneal deposits. CNS/GI disturb. Can cause torsades. Heart block. Low bp. Nightmares. Abn LFT. Inhibits -450

70
Q

Sotalol

Class

A

Class II and III. Nonselective beta adrenergic antag.

71
Q

Sotalol

Indic

A

Severe sustained vtach and vfib, prevents reoccurrence of tachyarrythmias, esp aflutter and Afib

72
Q

Sotalol
SE
Cation
Excretion

A

Prolongs QTi, bradycardia, myoc depression, fatigue, dyspnea, AV block
Asthma pts
Urine

73
Q

Ibutilide
Class
Indic

A
Pure class III 
Conversion afib/flutter, control rate. Prolongs AP duration and increases refractory period.
74
Q

Dofetilide
Class
Route
Indic

A

Class III. Oral. Maintenance NSR after afib or conversion.

75
Q

Dofetilide
SE
Ok in who

A

Proarrythmic

Post MI pts

76
Q

Class IV agents

Primary site/action

A

Blocks slow ca ch. primary site at AV node. Dec conduction thru AV, shortens phase 2 (plateau), of AP in ventricular myocytes. Contractility dec.

77
Q

Class iv
Indications
Not used in

A

SVT, ventricular rate control in afib/aflutter.
Prevents reoccurrence SVT
Not used in ventricular arrhythmias

78
Q

Class IV agents

Ex

A

Ca ch blockers
Verapamil- prototype
Diltiazem

79
Q

Verapamil

Dose

A

2.5-10 mg iv over 1-3 min. Max dose 20 mg.

Continuous gtt 5 mcg/kg/min

80
Q

Verapamil
Dont use iv w/what
1/2 life

A

B blocker, heart block

6-8 hrs

81
Q

Verapamil
Highly what
Metab
Excretion

A

Protein bound
Hepatic w active metabolite
Urine and bile

82
Q

Verapamil

SE

A

Myocardial depression, hypotension, constipation, bradycardia, nausea, prolongs NMB

83
Q

Verapamil

Caution

A

Myo dep and vasodil w inhalational drugs. Pot NMB. LA toxicity inc risk. Hyperkalemia w dantrolene. Dec dig clearance. Contraindication in WPW. Caution w BB

84
Q

Dilt
Class
Dose

A

IV, Ca ch blocker
5-20 mg iv (0.25-0.35 mg/kg) over 2 min
Gtt 10 mg/hr

85
Q
Dilt 
1/2 life 
Highly what 
Metab 
Excretion
A

4-6 hrs
Protein bound
Hepatic
Urine

86
Q

Dilt

SE

A

Myocardial depression, hypotension, constipation, bradycardia, nausea, prolongs NMB

87
Q

Class V drugs 3

A

Adenosine, digoxin, atropine

88
Q

Adenosine

Action

A

Binds to A1 purine nucleotide receptors, opens K channels. Slows AV nodal conduction

89
Q

Adenosine

Indic `

A

Acute rx, terminated SVT or dx of VT

90
Q

Adenosine
Dose
Duration
Elim

A

6 mg IV fast bolus. Repeat in 3 min, 6-12 mg iv
20-30 secs
Vascular endothelial enzymes

91
Q

Adenosine
SE
Contraindicated in

A

AV/SA node inhib, flushing, HA, dizzy, SOB, CP, nausea, bronchospasm
Contra: asthma and heart block

92
Q

Digoxin
What it is
Action

A

Cardiac glycoside
Inc vagal activity, dec SA node activity and prolongs conduction thru AV node. Dec HR, preload, and afterload. Inc contractility in CHF

93
Q

Dig

Indication

A

Manage afib or flutter, controls ventricular rate, esp w imp heart func

94
Q

Digoxin
Dose
Onset
t 1/2

A

0.5-1 mg divided doses over 12-24 hrs
Onset 30-60 min
36 hrs

95
Q

Digoxin
Therapeutic index
Weak what
Excretion

A

Narrow, 0.5-1.2 ng/ml
Protein binding
90% kidneys, reduce in elderly and renal impaired

96
Q

Digoxin

AE

A

Arrhythmias, heart block, anorexia, nausea, diarrhea, confusion, agitation

97
Q

Digoxin
Potentiated by
Toxicity tx

A

Hypokalemia and hypomagnesemia

Phenytoin (vent arrhythmias), pacing, atropine, antidote: immune fab

98
Q

Atropine
Class
Indic

A

Muscarinic receptor antag

Unstable bradyarrythmias

99
Q

Atropine
Dose
Onset
Duration

A

0.4-1 mg IV
1 min
30-60 min

100
Q

Atropine
Metab by
Cation dosing less than what, why

A

Liver.

0.4 mg, paradoxical response, penetrates BBB and CNS fx