PSC 434 Chapter 17: Antiarrhythmic Drugs
17 Feb 2019
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Naldolol: class iii (k+ channel blockers): amiodarone, dofetilide, sotalol, bretylium, napa, class iv (ca2+ channel blockers): diltiazem, verapamil, other antiarrhythmic drugs: adenosine, digoxin. Parkinson-white syndrome): atrial arrhythmias: atrial flutter (propranolol, verapamil, digoxin) and atrial fibrillation, atrial fibrillation: this common arrhythmia involves multiple ectopic foci of atrial cells, creating a chaotic movement of impulses through the atria. The ventricular response is rapid (100-150 per minute) and irregular. Beta blockers are the drugs of choice in this arrhythmia, because they decrease heart rate and promote conversion to sinus rhythm. However, if cardiac sites other than the sa node show enhanced automaticity, they may generate competing stimuli, and arrhythmias may arise. Increased sympathetic activity increases the rate of phase 4 depolarization. Intrinsic disease yields faulty pacemaker activity (sick sinus syndrome): abnormal automaticity may also occur if the myocardial cells are damaged. Reentry is the most common cause of arrhythmias.
