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Anti-arrhythmic Drugs: Class II

Class II: Beta blockers

Treat both supraventricular and ventricular arrhythmias.

Slow channel blockers*, so they work at the sinoatrial and atrioventricular nodes; more generally, as we've learned elsewhere, beta blockers reduce sympathetic stimulation.

We draw the normal curve of an action potential through the nodes.

Then, we show that beta blockers inhibit phase 4 depolarization and slow conduction through the atrioventricular node.*

Suppress ectopic pacemakers.
Slow heart rate and reduce contractility.
Prolong the PR interval on ECG.
Examples

– Drugs that are often used to prevent recurrent myocardial infarction: Propranolol, which also stabilizes membranes (a class I action) Metoprolol Nadolol Timolol – Esmolol is a cardioselective beta-1 receptor blocker and is short-acting. – Thus, it is used to treat acute arrhythmias.

Common beta blocker side effects: bradycardia, hypotension, bronchospasm (with non-selective beta blockers, specifically), and, myocardial depression.

For References, please see our full tutorial on Class II anti-arrhythmic drugs.

Anti-arrhythmic Drugs: Class II

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