Beta Blockers

Question 1

Name some cardioselective beta blockers?

Answer 1

Atenolol, Metoprolol and Bisoproplol

Question 2

Name some non cardioselective beta blockers?

Answer 2

Propanolol

Question 3

How do beta blockers work?

Answer 3

Block beta receptors on the heart (B1) and smooth muscle of vessels and airway (B2)
Beta receptors have a sympathetic effect causing:
- Vasoconstriction
- Brochodilation
- Increased force of the heart
- Increased rate of the heart due to increased conductions
Beta blockers work by causing:
- Vasodilation
- Bronchoconstriction
- Decreased force of the heart
- Decreased rate of the heart
**They also decrease rennin release from the kidney

Question 4

How do beta blockers work on the AV node?

Answer 4

Prologue the refractory period of the atrioventricular (AV) node

Question 5

How do beta blockers work in AF and SVT?

Answer 5

They slow the ventricular rate in atrial fibrillation mainly by prolonging the refractory period of the atrioventricular (AV) node.
SVT often involves a self-perpetuating (‘re-entry’) circuit that takes in the AV node; β-blockers may break this and restore sinus rhythm.

Question 6

What are the common uses of beta blockers?

Answer 6

1. IHD: first line use for angina, and Acs; also used 12 hours after an MI
2. CHF: first line use to improve prognosis
3. AF: slow ventricular rate at AV node - works in paroxysmal as well
4. SVT: first line as restores sinus rhythm
5. Hypertension
6. Panic disorder/hyperthyroidism

Question 7

What are the contra-indications of using beta blockers?

Answer 7

Asthma
Heart block
Bradycardia
Haemodynamic instability
Pregnancy

Question 8

When should you use beta blockers with caution?

Answer 8

COPD (chose a cardio selective one)
Hepatic and renal insufficiency (lower dose)
Heart failure - START LOW GO SLOW

Question 9

What is the rule when using Beta blockers in HF?

Answer 9

START LOW GO SLOW

Question 10

What are some common interactions with beta blockers?

Answer 10

• Non-dihydropine calcium channel blockers e.g. verapamil and diltazem
• Other anti-arrythmics and anti hypertensives
• NSAIDS can reduce effects of atenolol

Question 11

Why should you never use non-dihydropine CCBs with beta blockers?

Answer 11

Can cause bradycardia, HF and a-systole

Question 12

What are the common side effects of using beta blockers?

Answer 12

• bradycardia
• cold extremities
• fatigue and sob
• GI disturbance
• Sleep disturbances (less in atenolol)
• Impotence