Sinus node disease. Current concepts in diagnosis and therapy.

Sinus node disease (SND) encompasses a number of abnormalities of sinus impulse generation and transmission within the atria and may lead to both bradyarrhythmias and tachycardias. Such abnormalities may be due to primary atrial electrophysiological abnormalities, or be secondary to drugs or abnormal autonomic control. The diagnosis may be readily established from the surface ECG or Holter recordings in many cases, but invasive electrophysiological study or assessment of the effects of autonomic blockade may be required in symptomatic patients in whom the diagnosis is suspected but not confirmed by simple electrocardiographic monitoring. Treatment should be restricted to those patients in whom clear correlation between symptoms and electrocardiographic or electrophysiological abnormalities has been established. Although a number of pharmacological agents have been assessed, the treatment of bradyarrhythmias should be permanent pacing. There is now substantial evidence that physiological (atrial or dual chamber) pacing reduces atrial arrhythmias, systemic embolisation, progression to heart failure and mortality, compared to single chamber ventricular pacing. Antiarrhythmic therapy may be required to control atrial tachyarrhythmias if they persist following pacing. In patients with uncontrolled atrial arrhythmias, especially those with ventricular pacemakers, long term oral anticoagulation should be considered to reduce the risk of systemic embolisation which is a common complication in patients with the bradycardia/tachycardia syndrome.