Final answer:
Beta-blockers like propranolol treat cardiac arrhythmias by blocking ß-receptors, which leads to a decrease in heart rate and often a decrease in blood pressure, thereby improving cardiac function and rhythm.
Step-by-step explanation:
Beta-blockers like propranolol are commonly used to treat cardiovascular diseases, including cardiac arrhythmias. Their primary mechanism of action is to block ß-receptors, which are associated with cardioacceleration and vasoconstriction. As a result, these drugs prevent increases in heart rate and support the dilation of blood vessels, leading to improved cardiac function.
For arrhythmias, this action translates to a decrease in heart rate (HR). Propranolol nonselectively blocks ß-receptors, which can help in restoring and maintaining a normal heart rhythm and also often leads to a decrease in blood pressure. However, excessive use of beta-blockers can result in bradycardia or in severe cases, a complete stoppage of the heart.
Learn more about Beta-blockers