Final answer:
Antiarrhythmics, including beta-blockers, calcium channel blockers, and sodium channel blockers, can change the QT interval. Potassium channel blockers, such as amiodarone and procainamide, can particularly affect the T wave by delaying ventricular repolarization.
Step-by-step explanation:
Antiarrhythmics that can change the QT interval include sodium channel blockers, potassium channel blockers, beta-blockers, and calcium channel blockers. Each of these drug classes can impact the cardiac action potential in different ways, potentially affecting the QT interval on an electrocardiogram (ECG). Specifically, the QT interval represents the time from the start of ventricular depolarization to repolarization.
Potassium channel blockers, like amiodarone and procainamide, delay repolarization of the ventricles by impeding the movement of K+ through voltage-gated K+ channels, which can prolong the QT interval. This primarily affects the T wave of the cardiac action potential, which represents ventricular repolarization. Calcium channel blockers slow the heart rate by binding to calcium channels and blocking the inward movement of calcium ions, which can also influence the QT interval by affecting the duration of the action potential. Beta-blockers exert a negative inotropic effect and can additionally alter the QT interval, though their primary effect is on slowing the heart rate.