McKenna's Pharmacology for Nursing, 2e

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Antiarrhythmic agents

Learning objectives Upon completion of this chapter, you should be able to: 1. Describe the cardiac action potential and its phases to explain the changes made by each class of antiarrhythmic agents. 2. Describe the therapeutic actions, indications, pharmacokinetics, contraindications and cautions, most common adverse reactions and important drug–drug interactions associated with antiarrhythmic agents. 3. Discuss the use of antiarrhythmic agents across the lifespan. 4. Compare and contrast the prototype antiarrhythmic drugs lignocaine, propranolol, amiodarone and diltiazem with other agents in their class and with other classes of antiarrhythmics. 5. Outline the care considerations, including important teaching points, for people receiving antiarrhythmic agents.

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Glossary of key terms antiarrhythmics: drugs that affect the action potential of cardiac cells and are used to treat arrhythmias and restore normal rate and rhythm bradycardia: slower-than-normal heart rate (usually less than 60 beats/minute) Cardiac Arrhythmia Suppression Trial (CAST): a large research study run by the US National Heart and Lung Institute found that long-term treatment of arrhythmias may have a questionable effect on mortality, and in some cases actually lead to increased cardiac death; basis for the current indication for antiarrhythmics (short-term use to treat life-threatening ventricular arrhythmias) cardiac output: the amount of blood the heart can pump per beat; influenced by the coordination of cardiac muscle contraction, heart rate and blood return to the heart haemodynamics: the study of the forces moving blood throughout the cardiovascular system heart blocks: blocks to conduction of an impulse through the cardiac conduction system; can occur at the atrioventricular node, interrupting conduction from the atria into the ventricles, or in the bundle branches within the ventricles, preventing the normal conduction of the impulse premature atrial contraction (PAC): caused by an ectopic focus in the atria that stimulates an atrial response premature ventricular contraction (PVC): caused by an ectopic focus in the ventricles that stimulates the cells and causes an early contraction proarrhythmic: tending to cause arrhythmias; many of the drugs used to treat arrhythmias have been found to generate them tachycardia: faster-than-normal heart rate (usually greater than 100 beats/minute)

Class Ic flecainide propafenone Class II antiarrhythmics esmolol propranolol

ANTIARRHYTHMIC AGENTS Class I antiarrhythmics Class Ia disopyramide Class Ib lignocaine

Class III antiarrhythmics amiodarone sotalol Class IV antiarrhythmics

Other antiarrhythmics adenosine digoxin

diltiazem verapamil