Sick Sinus Syndrome

Sick sinus syndrome (SSS) is a relatively common arrhythmia that is associated with disorder of impulse formation in the cardiac atria. Many people with SSS have no visible problems, but other may suffer from a variety of unpleasant symptoms.


Normally, the electric impulse that causes contraction of heart muscle cells is formed in a single location, which is called the sinoatrial (SA) node. From the SA node, the excitement spreads throughout the atria (followed by atrial contraction) and through the atrioventricular (AV) node into the ventricular muscle where it is followed by a systole (ventricular contraction).


SSS occurs when there is a malfunction of SA node. The impulses occur irregularly and in various speeds. The situation most commonly occurs in the elderly, in patients with chronic heart diseases and in patients with untreated hypertension. The age is clearly an important risk factor.


SSS may manifest with more kinds of arrhythmias that may change one in another. The arrhythmias include too slow rhythm (bradycardia) alternating with rapid rhythm episodes (tachycardia). The patients may suffer from recurring episodes of rapid or slow atrial fibrillation. The resulting symptoms may include fatigue, palpitations, chest pain, dizziness, shortness of breath, episodes of unconsciousness, heart failure, etc. The majority of these symptoms occur due to inadequate cardiac output because of too fast or too slow heartbeat.


The suspicion of abnormal heart rhythms may be found during physical examination and confirmed by ECG. However, it is important to realize that the rhythm disturbances in SSS are paroxysmal and between these attacks, there may be periods of absolutely normal heartbeat. Therefore, it is advisable to use ECG Holter monitor, which is a device attached to chest monitoring the ECG for a longer time period, usually for 24-72 hours. The patient wears the device during normal daily activities and also during sleep. After the examination, a cardiologist can check the record and look for any arrhythmias.


Symptomatic sick sinus syndrome manifesting with bradycardia must be usually treated by implantation of a pacemaker, which does not allow the heart to beat too slowly. Tachycardia can be treated by various medications that decrease the heart rate such as the beta-blockers. When there are confirmed episodes of atrial fibrillation, the patient should be administered anticoagulants.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Sources: basic text sources