ABSTRACT

Supraventricular rhythms are those which arise above the level of the ventricles, that is, from the sinoatrial (SA) node, the atria or the atrioventricular node. This includes normal rhythms, abnormal rhythms, and rhythms which may or may not be ‘normal’ depending upon the clinical context. Sinus rhythm is the normal cardiac rhythm, in which the SA node acts as the natural pacemaker, discharging at a rate of 60– 100/min. Sinus arrhythmia is the variation in heart rate that is seen during inspiration and expiration. Physiological causes of sinus tachycardia include anything that stimulates the sympathetic nervous system – anxiety, pain, fear, fever or exercise. When a patient has an appropriate tachycardia, the tachycardia is helping to maintain the patient’s blood pressure and so slowing it with beta blockers can lead to disastrous decompensation. It is the underlying problem that needs addressing.