Chapter 25: Antidysrhythmic Drugs

Understanding these physiological principles is essential for comprehending how antidysrhythmic agents work at the cellular level. The chapter discusses clinically significant dysrhythmias including atrial fibrillation, atrial flutter, paroxysmal supraventricular tachycardia, premature ventricular contractions, ventricular tachycardia, torsades de pointes, and ventricular fibrillation, each with distinct hemodynamic consequences ranging from decreased cardiac output to thromboembolic complications and sudden cardiac death. The Vaughan Williams classification system organizes antidysrhythmic drugs into four functional categories based on their primary mechanism of action: Class I agents block sodium channels and include drugs like procainamide, quinidine, lidocaine, flecainide, and propafenone; Class II drugs are beta adrenergic antagonists such as atenolol, metoprolol, and esmolol; Class III medications inhibit potassium channels and include amiodarone, sotalol, ibutilide, and dofetilide; Class IV agents block calcium channels with verapamil and diltiazem as examples. Additionally, adenosine serves as an unclassified agent particularly effective for certain supraventricular rhythms. The chapter emphasizes significant adverse effects including hypotension, bradycardia, QT interval prolongation, proarrhythmic effects, and drug-specific toxicities such as pulmonary and thyroid complications associated with amiodarone use. Nursing responsibilities encompass continuous electrocardiographic monitoring, vital sign assessment, electrolyte evaluation, patient education regarding symptom reporting, recognition of photosensitivity concerns, and careful medication administration with attention to complex dosing regimens and potential drug interactions with digoxin, warfarin, and other cardiac medications.