Cardiac arrhythmias result from alterations in the orderly sequence of depolarization followed by repolar-ization in the heart. Cardiac arrhythmias may result in alterations in heart rate or rhythm and arise from alter-ations in impulse generation or conduction. The clinical implications of disordered cardiac activation range from asymptomatic palpitations to lethal arrhythmia.
Pharmacological management of arrhythmias uses drugs that exert effects directly on cardiac cells by in-hibiting the function of specific ion channels or by al-tering the autonomic input into the heart. Recent tech-nological advances have lead to an increase in nondrug strategies, including transcatheter radiofrequency abla-tion, intraoperative cryoablation, implanted pacemak-ers, and defibrillation. Physicians caring for patientswith arrhythmias therefore must understand and appre-ciate the benefits and risks provided by each therapeu-tic modality, what the indication for each is, and how these modalities may interact.
Successful antiarrhythmic drug therapy requires a combination of understanding the pathophysiology of the arrhythmia, identification of a drug that can influ-ence the relevant electrophysiological parameters, and careful titration of the drugâ€™s dose to correct the abnor-mal electrophysiological events giving rise to the ar-rhythmia. This is accomplished while avoiding the om-nipresent risk of side effects such as proarrhythmia.