Beta Blockers

Introduction

• Beta blockers block beta receptors in the body, preventing norepinephrine and epinephrine from binding.
• Norepinephrine and epinephrine play a large role in the sympathetic nervous system (fight or flight).
• Blocking these receptors inhibits the sympathetic nervous system response.
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Sympathetic Nervous System

• Function: Increases heart rate, blood pressure, cardiac output, and oxygen consumption by the myocardium; increases heart contraction strength; causes bronchodilation and increased blood glucose.

Beta Receptors

• Beta 1 Receptors: Mainly in the heart and kidneys (juxtaglomerular cells). Responsible for the renin-angiotensin-aldosterone system (RAS).
• Beta 2 Receptors: Mainly in the lungs, GI system (liver), vascular smooth muscle, skeletal muscle, and ciliary body of the eye.
• Beta 3 Receptors: Found in adipose tissue.

Types of Beta Blockers

• All beta blockers end with LOL.

Selective Beta Blockers (Target Beta 1 receptors)

• Mainly affect cardiac function.
• Examples: Atenolol, Esmolol, Metoprolol.

Non-Selective Beta Blockers (Target Beta 1 and Beta 2 receptors)

• Affect the heart and other systems (lungs, vascular smooth muscle, etc).
• Examples: Propranolol, Sotalol, Timolol.

Mechanism of Action

Shared Effects

• Both types produce cardiac effects by targeting beta 1 receptors.
• Actions:
  • Treat dysrhythmias (slow fast heart rates).
  • Monitor for severe bradycardia and heart blocks (2nd or 3rd degree).
  • Decrease myocardium contraction strength (negative inotropic effect) to reduce oxygen consumption.
  • Lower blood pressure by inhibiting renin release in kidneys.

Non-Selective Beta Blockers (Additional Effects)

• Decrease intraocular pressure: Useful in glaucoma.
• Cause bronchoconstriction: Not suitable for asthma or COPD patients.
• Affect blood glucose: Potential hypo/hyperglycemia, mask tachycardia in hypoglycemic diabetics.
• Peripheral vasoconstriction: Can lead to erectile dysfunction and cold extremities; unsuitable for peripheral vascular disease patients.

Uses of Beta Blockers

• Treat high blood pressure.
• Manage stable angina (chest pain from coronary artery disease).
• Treat dysrhythmias (supraventricular tachycardia).
• Manage compensated heart failure.
• Treat glaucoma, migraines, tremors, and anxiety.

Nursing Considerations and Patient Education

Mnemonic: BETA BLOCK

• B: Bradycardia and heart blocks (2nd and 3rd degree) - Monitor heart rate and rhythm.
• E: Exacerbate heart failure - Watch for symptoms like crackles in lungs, weight gain, extremity swelling.
• T: Taper off - Never stop abruptly, risk of rebound hypertension and myocardial ischemia.
• A: Asthma and COPD - Avoid non-selective beta blockers.
• B: Blood glucose - Monitor closely for hypo/hyperglycemia; mask tachycardia in diabetics.
• L: Lower blood pressure - Monitor for hypotension.
• O: Orthostatic hypotension - Advise slow position changes to avoid dizziness and falls.
• C: Circulation impaired - Potential cold extremities, erectile dysfunction; avoid in peripheral vascular disease.
• K: Know signs of overdose - Severe bradycardia, severe hypotension, mental status changes, heart blocks.

Conclusion

• Beta blockers are a critical class of medication with significant effects on the cardiovascular system and other body systems.
• Monitoring and patient education are crucial to ensure safe and effective treatment.
• Access the free quiz on RegisteredNurseRN.com to test your knowledge.