Causes and diagnosis of an acute tachyarrhythmia
A tachyarrhythmia is an abnormal heart rhythm in which the ventricular rate is 100 or more beats per minute. Tachyarrhythmias can present simply as palpitations but can also affect cardiac function and cause haemodynamic compromise. An initial step in management of tachyarrhythmias is to distinguish between supraventricular and ventricular origin. It is not always possible to determine the site of origin; in such cases, the arrhythmia should initially be managed as a ventricular tachycardia. Many tachyarrhythmias have a relatively benign nature, and some may be infrequent, self-limiting or asymptomatic. Treatment should rarely be started for palpitations alone without a diagnosis being made using a 12-lead electrocardiogram (ECG).
Always consider underlying abnormalities and the causes of acute tachyarrhythmia; for example:
- electrolyte abnormalities (eg hypokalaemia, hypomagnesaemia)
- myocardial ischaemia
- sepsis
- hypoxia
- proarrhythmic drugs, including drugs used to treat arrhythmias.