Antidysrhythmic Medications Lecture Notes

Introduction

• Focus on antidysrhythmic medications, specifically:
  • Cardiac glycosides
  • Class I and II antidysrhythmic medications

Cardiac Glycosides

• Digoxin
  • Used for heart failure, atrial fibrillation, and atrial flutter.
  • Mode of Action:
    • Positive inotropic effect: Increases force and efficiency of heart contractions.
    • Negative chronotropic effect: Decreases heart rate.
  • Side Effects:
    • Dysrhythmias (e.g., bradycardia)
    • Digoxin toxicity: GI upset, fatigue, vision issues.
  • Administration Considerations:
    • Monitor pulse before administration; hold if <60 bpm.
    • Monitor digoxin levels (Therapeutic range: 0.5-2).
    • Risk of toxicity increased with hypokalemia.
  • Treatment:
    • Bradycardia: Treated with Atropine.
    • Digoxin toxicity: Treated with Digoxin immune fab (Digibind).
  • Mnemonic: "Dig slow and deep" to remember its effects on contractions.

Class I Antidysrhythmics

• Sodium Channel Blockers
  • Examples: Procainamide, Lidocaine (both contain "cain").
  • Uses: Ventricular dysrhythmias, supraventricular tachycardia.
  • Side Effects:
    • Hypotension, dysrhythmias, lupus, leukopenia, thrombocytopenia.
    • Black box warning for prolonged use: Positive ANA (autoimmune response).
  • Monitoring:
    • EKG, vital signs, CBC, and procainamide blood levels (Therapeutic range: 4-8).

Class II Antidysrhythmics

• Beta Blockers
  • Examples: Propranolol, Metoprolol, Atenolol.
  • Uses: Dysrhythmias (atrial fibrillation, atrial flutter, ventricular dysrhythmias).
  • Side Effects:
    • Hypotension, bradycardia, fatigue, weakness, erectile dysfunction.
    • Nonselective (e.g., propranolol) can cause bronchospasm.
  • Considerations:
    • Avoid nonselective beta blockers in asthmatic patients (risk of bronchospasm).
  • Mnemonics:
    • Beta-1: "One ma" - Metoprolol, Atenolol.
    • Nonselective: "Please listen carefully" - Propranolol, Labetalol, Carvedilol.

Conclusion

• Next video will cover Class III, IV, and V antidysrhythmic medications.
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