antiarrhythmic /-ərith″mik/ [Gk, anti + rhythmos, rhythm] , 1. pertaining to a procedure or substance that prevents, alleviates, or corrects an abnormal cardiac rhythm. Kinds include defibrillator, pacemaker. 2. an antiarrhythmic agent. The major antiarrhythmic drugs are lidocaine hydrochloride, and a combination of disopyramide phosphate, procainamide hydrochloride, and quinidine. The antiadrenergic blocking agent propranolol hydrochloride may be used in treating arrhythmias. Isoproterenol hydrochloride is indicated for complete heart block and ventricular arrhythmias requiring an increased force of cardiac contractions to establish a normal rhythm. Atropine may be used in the treatment of bradycardia, a sedative in the treatment of tachycardia, and digitalis in the treatment of atrial fibrillation. Calcium channel blockers control arrhythmias by inhibiting calcium ion influx across the plasma membrane of cardiac muscle, thus slowing atrioventricular conduction and prolonging the effective refractory period within the AV node. See also arrhythmia.
