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Treatment for bradycardia?
- Atropine
- Isoproterenol (beta agonist)
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Class I anti-arrhythmic drug - MoA
- Na channel blockers
- prolong effective refractory period
- greatest effect on fast heart rate
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Class II anti-arrhythmic drug - MoA
- Beta-blockers
- decrease AV conductance
- prolong phase 4 depolarization
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Class III anti-arrhythmic drug - MoA
- K channel blockers
- prolong QT interval (can lead to torsade de points)
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Class IV anti-arrhythmic drug - MoA
- Calcium Channel Blockers
- block AV conduction
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Class Ia - MoA
- block OPEN Na & K channels
- prolong QRS & QT
- prolong AP duration
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Class Ib - MoA
- block INACTIVATED Na channels
- little effect on QRS
- shortens AP duration
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Class Ic - MoA
- block OPEN Na channels
- prolong QRS
- No Change on AP duration
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What does blocking of Na channel does on the EKG?
prolong QRS interval
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What does blocking of K channel does on the EKG?
prolong QT interval
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What can prolong QT interval do?
cause Torsades de Pointes
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Quinidine - MoA
- Class Ia anti-arrhythmic
- alpha-blocking action
- anti-muscarinic (leads to decrease AV node refractory period => ventricular tachycardia)
- give AV blocker when using this drug
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Quinidine - Use
- Supraventricular tachycardia
- ventricular tachycardia (w/ AV blocker)
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Quinidine - Adverse Effects
- GI irritant
- Cinchonism (ringing in ear)
- CYP450-2D6 inhibitor => increase warfarin
- increase digoxin conc.
- torsades de pointes
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Procainamide - MoA
- Class Ia
- converts to NAPA => prolong AP, does not block Na channels
-
Procainamide - Use
Ventricular tachycardia
-
Procainamide - Adverse Effect
- SLE like symptoms
- NAPA => torsade de pointes in renal failure
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Lidocaine - Use
- Ventricular arrhythmia
- Digoxin induced arrhythmia
-
Lidocaine - Adverse Effect
- Neurologic toxicity
- (drowsy, confuse, nystagmus)
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Flecainide - MoA
Class Ic
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Flecainide - use
- Life threatening V. fib
- Refractory or symptomatic Supraventricular arrhythmia
- severe arrhythmias
-
Flecainide - Adverse Effect
- negative inotropic effect
- pro-arrhythmogenic (esp. in MI)
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Class II - Beta Blockers - MoA
- prolong AV conduction
- diminish phase 4 depolarization
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Class II - Use
- prevent re-infarction & sudden death after MI or CHF
- control ventricular rate
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Amiodarone - MoA
- Class III - K blocker
- block K & INACTIVATED Na channel
- inhibits Ca channels
- contains Iodine (thyroid)
-
Amiodarone - Use
Ventricular & Atrial Arrhythmia
-
Amiodarone - Adverse effects
- Pulmonary fibrosis (irreversible)
- skin pigmentation
- hypothyroid (iodine)
- inhibits CYP450 => inc. digoxin
- hepatotoxicity, corneal opacity
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Dofetilide
- Class III
- Atrial fib & flutter
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Ibutilide
- Class III
- Atrial fib & flutter
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Verapamil
Dilitiazem
- class IV - CCB
- Use: PSVT treatment, controls ventricular rate & A. fib
- AE: decrease contractility of heart
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Adenosine - MoA
- Activate K channels in AV node
- short acting (~10s), AV blocking drug that resets the heart rhythm
-
Adenosine - Use
drug of choice for PSVT
-
Adenosine - Adverse Effect
Bronchospasm (but short acting)
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