Beta-Blockers in Angina — Receptors, Mechanism & Withdrawal
Module 3 · Visual Summary
Receptor Effects
Cardiac
Beta-1
  • Heart rate, contractility
  • Blockade is anti-ischemic
Peripheral / Pulmonary
Beta-2
  • Bronchodilation, vasodilation
  • Blockade causes bronchoconstriction
Vascular
Alpha-1
  • Vasoconstriction
  • Unopposed when beta-2 is blocked
Two Hemodynamic Effects in Angina
Demand Down
Lower heart rate and contractility reduce myocardial oxygen consumption
Supply Up
Slower heart rate lengthens diastole, increasing coronary filling time
Withdrawal Syndrome
Never Stop Abruptly
Chronic blockade causes receptor upregulation. Sudden discontinuation exposes the expanded receptor population to normal catecholamines, producing rebound tachycardia, hypertension, and potentially rebound angina or myocardial infarction. Always taper over one to two weeks.