What is the primary effect of beta blockers on the heart?

What is the primary effect of beta blockers on the heart?

• A. Decrease heart rate and decrease cardiac workload
• B. Increase heart rate
• C. Increase myocardial contractility
• D. Decrease blood pressure only

Answer: (A)

Beta blockers blunt the heart’s adrenergic stimulation, especially at beta-1 receptors. This slows the heart and weakens its contractions, reducing the amount of work the heart has to do and its oxygen demand. So the primary effect on the heart is a decrease in heart rate and a decrease in cardiac workload. The other options describe opposite or incomplete effects: increasing heart rate would not occur, and increasing contractility would oppose what beta blockers do. Saying they decrease blood pressure only misses the direct impact on heart rate and contractility, even though lower pressure can be a consequence.

Beta blockers blunt the heart’s adrenergic stimulation, especially at beta-1 receptors. This slows the heart and weakens its contractions, reducing the amount of work the heart has to do and its oxygen demand. So the primary effect on the heart is a decrease in heart rate and a decrease in cardiac workload.

The other options describe opposite or incomplete effects: increasing heart rate would not occur, and increasing contractility would oppose what beta blockers do. Saying they decrease blood pressure only misses the direct impact on heart rate and contractility, even though lower pressure can be a consequence.