Cardiology · USMLE Step 1 and Step 2

Beta Blockers song

Beta Blockers - Selectivity, Uses & Toxicity, as a song. Hear the short teaser here. The full song is on YouTube and Spotify.

Beta Blockers

Full song on YouTube ↗Spotify ↗

Key points in this song10

Beta blockers competitively antagonize catecholamines at β-adrenergic receptors, reducing heart rate, contractility, and blood pressure by blocking β1 receptors on the heart.
β1-selective blockers (metoprolol, atenolol, bisoprolol) preferentially block cardiac β1 receptors and are safer in asthma and COPD compared to non-selective agents.
Non-selective beta blockers (propranolol, carvedilol, nadolol) block both β1 and β2 receptors; β2 blockade can cause bronchoconstriction and mask hypoglycemia symptoms except sweating.
Carvedilol and labetalol additionally block α1 receptors, providing vasodilation and making them useful in hypertensive emergencies and heart failure.
Beta blockers are first-line in post-MI patients, reducing mortality by decreasing myocardial oxygen demand and preventing ventricular remodeling.
Beta blockers are a cornerstone of heart failure with reduced ejection fraction (HFrEF) therapy; carvedilol, metoprolol succinate, and bisoprolol have proven mortality benefit.
Beta blockers are first-line for rate control in atrial fibrillation and atrial flutter by increasing AV nodal refractory period.
Propranolol is used for essential tremor, migraine prophylaxis, performance anxiety, hyperthyroidism symptom control, and portal hypertension.
Abrupt withdrawal of beta blockers can precipitate rebound hypertension, angina, or myocardial infarction due to upregulation of β receptors; always taper.
Contraindications include decompensated heart failure, cardiogenic shock, significant bradycardia or heart block, and Prinzmetal angina (unopposed α-mediated vasospasm).