Drugs that Regulate Cardiac Rhythm

The heart is both a mechanical and an electrical organ. The electrical component controls the rhythm of the heart. Under the influence of the autonomic nervous system, the sinoatrial (SA) node initiates action potentials, i.e., paces the heart at a normal resting rate of between 60 - 100 beats per minute.¹ Other pacemaker cells are found in the atrioventricular (AV) node, and the ventricular conducting system. Abnormal impulse generation and/or impulse conduction underlie cardiac arrhythmias.^7,8

The most common cause of cardiac arrhythmias is chronic coronary artery disease; less commonly, arrhythmias may be related to cardiomyopathies, valvular and congenital heart disease, primary electrophysiological disorders, and genetically determined ion-channel abnormalities.^1,8 Drugs in the top 300 that regulate cardiac rhythm (Table 4) include: (1) Na⁺ channel blockers, (2) β₁-adrenoceptor antagonists, (3) K⁺ channel blockers, (4) Ca²⁺ channel blockers, and (5) cardiac glycosides.^7,8,11