ABSTRACT
Recognising and identifying arrhythmias is an integral part of cardiology. Arrhythmias may impair cardiac output by causing bradycardia (bradyarrhythmias) or tachycardia (tachyarrhythmias). Bradyarrhythmias result from either sinus node dysfunction or atrioventricular block. Patterns of intraventricular conduction disease such as bundle branch block indicate a predisposition to bradycardia due to atrioventricular block. Tachyarrhythmias are either ventricular or supraventricular in origin. Supraventricular tachyarrhythmias include atrial fibrillation, atrial flutter, focal atrial tachycardia and re-entrant paroxysmal supraventricular tachycardia. Ventricular tachyarrhythmias are either monomorphic or polymorphic. Monomorphic ventricular tachycardia most often occurs in patients with structural heart disease, such as ischaemic heart disease, and is associated with an increased risk of sudden cardiac death. Polymorphic ventricular tachycardia and ventricular fibrillation are also associated a high risk of sudden cardiac death if prompt defibrillation is not performed. Wide QRS complex tachycardia is due to ventricular tachycardia, supraventricular with aberrancy or pre-excitation, pacemaker tachycardia or may be mimicked by motion artefact. This chapter describes the mechanism of these arrhythmias and focuses on the recognition and diagnosis of common arrhythmias.
