3)List Three Mechanisms of Arrhythmogenesis

Pharmacology

Lecture 11 Antiarrhythmic Drugs

1)Define cardiac arrhythmias.Arrhythmias are any abnormalities in heart rate, rhythm or a change in the site of the cardiac pacemaker resulting from alterations in the electrical activity of certain cardiac cells.

2)List the goals of antiarrhythmic therapy with drugs.The goal of antiarrhythmic therapy is to restore normal cardiac function, alleviate symptoms and prevent sudden cardiac death.

3)List three mechanisms of arrhythmogenesis.

Enhanced automaticy – the cardiac impulse originates in cells outside of the SA node that are undergoing spontaneous depolarization at a rate faster than the SA node.

Triggered automaticy – is characterized by after depolarizations, depolarizations that occur before or after full repolarization of the cell. After depolarizations can be early (EAD) or delayed (DAD).

Re-entry – occurs when there is slower conduction down one branch of fibers than on a neighboring branch such that the impulse on the normal branch depolarizes its cells and comes back the wrong direction. This occurs with congenital bypass tracts connecting atrium and ventricle, myocardial ischemia, and electrolyte imbalance. It produces atrial and ventricular fibrillation.

4)For each of the drugs discussed in this section, describe: electrophysiologic actions, antiarrhythmic actions, indications for use and adverse action both cardiac and non-cardiac.