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Pharmacology > Antidysrhythmics > Flashcards

Antidysrhythmics Flashcards

1
Q

Automaticity (vocab)

A

Heart’s ability to generate an electrical impulse.

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2
Q

Conductivity (vocab)

A

Ability of cardiac tissue to transmit electrical impulses.

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3
Q

Cardiac Action Potential (Patho)

A

Action potentials are generated by movement of ions into and out of the cell

Two types of action potentials in the heart:

Fast
Myocardium and His-Purkinje system
Conduct electricity quickly through the heart

Slow
SA and AV nodes
Differences in which ions impact each phase of the action potential

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4
Q

Formation of dysrhythmias (Patho)

A

Disturbances of automaticity
Cells other than the SA node depolarize and initiate an electrical impulse which causes a contraction
Can result in:
Tachydysrhythmias
Bradydysrhythmias
Area creating these impulses is called ectopic

Disturbances of conduction
Changes in electrical flow through the normal pathway in the heart
Can result in:
Atrioventricular block
Reentry pathways

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5
Q

Ectopic (vocab)

A

When the heart either skips a beat or adds an extra beat

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6
Q

Common dysrhythmias

A

Type of dysrhythmia divided based on location:
Supraventricular
Ventricular

Ventricular dysrhythmias more dangerous

Treatment includes 2 phases:
Termination of the dysrhythmia acutely
Long-term suppression of the dysrhythmia

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7
Q

Supraventricular dysrhythmias

A

Different types:
Supraventricular tachycardia
Atrial fibrillation
Atrial flutter

Less dangerous than ventricular dysrhythmias
No in cardiac output
Dangerous if:
Electrical impulses cross the AV node
↑ ventricular rate
GOAL:
Decrease impulse transmission through the AV node to decrease ventricular rate

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8
Q

Supraventricular tachycardia

A

Tachydysrhytmias
HR:>150 beats/min

Intervention:
Valsalva: forceful attempted exhalation against a closed airway, usually done by closing one’s mouth and pinching one’s nose shut while expelling air out as if blowing up a balloon.
Cardio version: shock/cpr

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9
Q

Atrial Fibrillation

A

Tachydysrhytmia
No coordinated atrial contraction
Stroke risk

Intervention:
Cardio version

Drug therapy:
Adenosine
Class II or IV

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10
Q

Atrial Flutter

A

Tachydysrhythmia
Coordinated atrial contraction
Stroke risk

Intervention:
Cardio version

Class II or IV drugs
Anticoagulation

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11
Q

Ventricular Dysrhythmias

A

Sustained ventricular tachycardia
Ventricular fibrillation
Torsades de pointes

Dangerous because these impact cardiac pumping and cardiac output
GOAL:
Abolish the dysrhythmia
First-line therapy typically cardioversion
Drugs are second-line

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12
Q

Classification of antidysrhythmic drugs

A

4 major classes
Class I: Sodium Channel Blockers
Class II: Beta-blockers
Class III: Potassium Channel Blockers
Class IV: Calcium Channel Blockers
Other: digoxin and adenosine

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13
Q

General Principles of Antidysrhythmic Agents

A

All antidysrhythmic drugs can also cause dysrhythmias

Balance risk and benefit
Only use when benefit outweighs risk
Type of dysrhythmia is the patient experiencing
Phases of treatment
Long term treatment: Drug selection and evaluation
Minimizing risks
Start with low doses
Monitor drug levels if indicated

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14
Q

Class I: Sodium Channel Blockers

A

Drugs:
Class IA
Disopyramide
Quinidine
Procainamide

Class IB
Lidocaine
Mexiletine

Class IC
Flecainide
Propafenone

Acronym
Double
Quarter
Pounder
Lettuce
Mayo
Fries
Please

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15
Q

Class I: Sodium Channel Blockers

A

Effects are secondary to sodium channel blockade
↓ conduction velocity in the atria, ventricles and His-Purkinje system
Divided into 3 subtypes
Similar in action and structure to local anesthetics

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16
Q

Disopyramide (Class IA)

A

Indication:
Ventricular dysrhythmias

Route:
Oral
IV

Adverse effects:
Anticholingeric properties
Negative inotrope

Other:
Limited clinical application
Monitor: ECG
Only given PO

17
Q

Quinidine (Class IA)

A

Indication :
Ventricular
Supraventricular dysrhythmias

Route:
Oral IV

Adverse effects:
Diarrhea
Cinchonism

Other:
Monitor: ECG, signs and symptoms of stroke

18
Q

Procainamide (Class IA)

A

Indication :
Ventricular
Supraventricular dysrhythmias

Route:
Oral
IV

Adverse effect:
Systemic Lupus Erythematosus
Blood dyscrasias
Arterial embolism

Other:
Start with IV then transition to oral therapy

Monitor: ECG, signs and symptoms of stroke

19
Q

Lidocaine (Class IB)

A

Indication:
Ventricular dysrhythmias

Route:
IV

Adverse effects:
CNS effects
Toxic doses:
Seizure
Respiratory arrest

Monitor:
Narrow therapeutic index
Drug levels
No effect on the ECG
Make sure you’re using the correct product!

20
Q

Mexiletine (Class IB)

A

Route:
PO

Adverse effects:
Nausea/vomiting
Constipation
Tremor/seizures

Monitoring:
No effect on ECG
Decrease dose in liver impairment or failure

21
Q

Flecainide (Class IC)

A

Indication:
Supraventricular dysrhythmias

Route:
PO

Adverse effects:
Nausea/vomiting
Dizziness
Blurred vision

Monitor:
VERY pro-dysrhythmic
Close attention to ECG
Increase mortality in post-MI patients with asymptomatic Vtach

22
Q

Propafenone (Class IC)

A

Indication:
Supraventricular dysrhythmias

Route:
PO

Adverse effects:
Nausea/vomiting
Dizziness
Blurred vision

Monitor:
Pro-dysrhythmic (not as much as Flecainide)
Close attention to ECG
Has some beta-blocking properties, use in caution in pts with AV block

23
Q

Class II Beta Blockers

A

Drugs Examples:
Propranolol
Acebutolol
Esmolol
Sotalol
Metoprolol
Labetalol
Bisoprolol
Carvedilol

24
Q

Class II Beta Blockers (continued)

A

Many different beta-blockers

Only 4 approved for treating dysrhythmias

Physiologic effects:
↓ automaticity in SA node
↓ conduction velocity through AV node
↓ myocardial contractility

Indications:
Sinus tachycardia
Atrial fibrillation/flutte

25
Q

Propranolol (Class II)

A

Indication:
Supraventricular tachycardias (Afib, Aflutter)
Sinus tachycardia

Route:
Oral
IV

Adverse effects:
AV block
Sinus arrest
Hypotension
Bradycardia

Monitor:
Give IV SLOWLY to avoid hypotension

Monitor: HR, BP, ECG

26
Q

Acebutolol (Class II)

A

Indication:
Supraventricular tachycardias (Afib, Aflutter)
Sinus tachycardia

Route: Oral

Adverse effects:
AV block
Sinus arrest
Hypotension
Bradycardia

Monitor: HR, BP, ECG

27
Q

Esmolol (Class II)

A

Indication:
Supraventricular tachycardias (Afib, Aflutter)
Sinus tachycardia

Route: IV

Adverse effects:
AV block
Sinus arrest
Hypotension
Bradycardia

Monitor:
VERY fast acting
Short half-life
Monitor: HR, BP, ECG

28
Q

Sotalol (Class II)

A

Indication:
Supraventricular tachycardias (Afib, Aflutter)
Sinus tachycardia

Route:
Oral

Adverse effects:
AV block
Sinus arrest
Hypotension
Bradycardia

Monitor:
Also causes blockade of K channels; can be considered Class III
Monitor: HR, BP, ECG

29
Q

Class III: Potassium Channel Blockers

A

Drugs examples:
Amiodarone
Ibutilide
Dofetilide
Dronedarone
Sotalol

30
Q

Class III: Potassium Channel Blockers (continued)

A

Delay repolarization of fast action potentials
Prolong the QT interval
All agents may have additional, unique effects on the heart. These agents are NOT interchangeable

31
Q

Amiodarone (Class II)

A

Mechanism of action:
↓ automaticity of the SA node
↓ reduced contractility
↓ conduction through the AV node
Delays repolarization

Indications:
Supraventricular dysrhythmias
Ventricular dysrhythmias

Administration:
Oral or IV

32
Q

Amiodarone (Class II) continued

A

Pharmacokinetics:
LONG half-life
Drug accumulates very well in tissues

Adverse effects:
Pulmonary pneumonitis and fibrosis
Hypo or hyperthyroidism
Liver toxicity
Optic neuropathy and optic neuritis
Photosensitivity
Do baseline
exams of all
organ systems
that can be
affected

Avoid use in pregnancy

33
Q

Class IV: Clacium Channel Blockers

A

Drug examples:
Diltiazem
Verapamil

Physiologic effects:
↓ SA node automaticity
↓ AV node conduction velocity
↓ myocardial contraction

Indications:
Atrial fibrillation and atrial flutter
Termination of SVT

Adverse effects:
Bradycardia
AV block
Exacerbate heart failure

34
Q

Adenosine (Class IV)

A

Naturally occurring nucleotide

Mechanism of action:
↓ automaticity of SA node
↓ conduction through the AV node
Prolonged PR interval

Indications:
Termination of supraventricular tachycardia (SVT)
NOT for treatment of afib or aflutter

35
Q

Adenosine (Class IV)

A

Pharmacokinetics
EXTREMELY short half-life (2 to 10 seconds)
Must be given IV push

Adverse effects:
Bradycardia
Momentary asystole
Dyspnea
Hypotension
Flushing
Chest discomfort

Drug interactions:
Methylxanthines (E.g. theophylline) – block adenosine receptors

36
Q

Administration of Adenosine (Class IV)

A

Must be given IV push
Dose must be
followed by a flush

Patient must be warned that they will feel uncomfortable during administration of this agent

Dose can be repeated up to 3 times

37
Q

Digoxin

A

Physiologic effects:
↓ conduction through the AV node
Increases vagal tone

Indications:
Atrial fibrillation
Atrial flutter

Last line agent for dysrhythmias

Benefit of digoxin = hemodynamically stable

Administration:
IV loading dose over 24 hours followed by oral therapy

Pharmacology (5 decks)

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