Beta blockers slow the heart. They do it by blocking beta-adrenergic receptors, the docking sites that respond to adrenaline and noradrenaline. With those signals muted, heart rate drops, blood pressure falls, and the heart uses less oxygen. For someone recovering from a heart attack, that combination saves lives.

The class is not uniform. Some beta blockers, like propranolol and metoprolol, are cardioselective at low doses, meaning they mainly affect the heart. Others, like carvedilol, also block alpha receptors and dilate blood vessels. Some have intrinsic sympathomimetic activity, a partial agonist effect that keeps the heart rate from dropping too far. The choice depends on the condition. Heart failure patients often get carvedilol, metoprolol succinate, or bisoprolol, the three proven to reduce mortality. Performance anxiety gets propranolol, taken an hour before a speech.

Common uses:

• Hypertension. Effective but no longer first-line for most patients.
• Heart failure. Reduces mortality when started carefully.
• Angina. Lowers oxygen demand and prevents chest pain.
• Arrhythmias. Slows electrical conduction and stabilizes rhythm.

Stopping a beta blocker abruptly can trigger rebound tachycardia or angina. Taper under medical supervision.