What is the main action of Class 2 antidysrhythmics?

Class 2 antidysrhythmics, primarily the beta-blockers, function mainly by slowing conduction velocity within the cardiac conduction system. These medications block the effects of adrenaline (epinephrine) and noradrenaline (norepinephrine) on beta-adrenergic receptors, effectively reducing heart rate and myocardial contractility. By doing so, they help in managing dysrhythmias, particularly those that involve excessive electrical activity such as atrial fibrillation and atrial flutter.

The slowing of conduction velocity is crucial in restoring a normal rhythm, especially in areas such as the atrioventricular (AV) node, where rapid conduction can lead to arrhythmias. This action contributes not just to the management of dysrhythmias but also aids in reducing the overall oxygen demand of the heart, which is beneficial in various cardiac conditions.

Other options, while relevant to different classes of antidysrhythmics, do not accurately represent the primary action of Class 2 agents. Widening the QRS complex typically involves sodium channel blockers (Class 1 agents), while decreasing automaticity may apply more broadly but is more associated with Class 4 calcium channel blockers. Increasing depolarization can relate to drugs that enhance excitability in certain