Sick Sinus Syndrome (SSS) or sinus node dysfunction refers to a group of irregular heart rhythms that are caused due to abnormal functioning of the sinus node (natural pacemaker of the heart). Sinus node, which is also called sinoatrial node, is located in the right atrium of the heart. Irregular heart rhythms include slow heart rate - usually 40 - 50 beats per minute (bradycardia), fast heartbeat - 100 beats per minute (tachycardia), and an alternation of both (bradycardia-tachycardia) with a long pause in between. SSS is more common among elderly people, and about 3 in 10,000 people suffer from this syndrome.

Causes

It is caused due to many reasons and many a time, it is idiopathic. Any disorder that causes inflammation, scarring, or damage of the sinus node and heart tissue, can lead to SSS. Some of the important causes include cardiac amyloidosis, a condition in which amyloid protein gets deposited in heart tissue that can affect sinus node, and cardiac myopathies that are characterized by abnormal functioning of muscles of the heart.

Sometimes, small inflammatory bumps known as sarcoidosis, that generally affects the lymph nodes appears in surrounding tissues of the heart and cause this condition. Other causes of SSS are arteritis (inflammation in the walls of arteries), Chagas disease (parasitic disease caused by protozoa), collagen vascular disease, and the use of certain drugs.

Symptoms and Diagnosis

Major symptoms of this syndrome are sinus arrest and sinoatrial block. In sinus arrest, there is cessation of sinus node activity, and in case of sinoatrial block, the electrical signal or impulse travels slowly, resulting in abnormally slow heart rate. Other common symptoms include chest pain, fainting, dizziness, fatigue, muscle pain, palpitation, confusion, and shortness of breath.

The condition is hard to diagnose, as the symptoms are vague and often confused with other diseases. Diagnosis is done based on heart rate, symptoms, medical history, and certain other tests. Electrocardiogram (ECG) is one of the most important equipment used to diagnose this condition. Instead of the standard ECG, which records the electrical activity of the heart for a brief period, the doctor may conduct holter monitor ECG and event recorder ECG in certain cases. In holter monitor, the heart rate is recorded for a 24-hour period with the help of a portable device. In case of event recorder ECG, recording of heart rate is done only when the symptoms of SSS occur.

Treatment

The treatment of this syndrome is usually done by implantation of an artificial pacemaker. This technique requires a minor surgery, wherein a small battery-operated electronic device is implanted under the skin, near the collarbone for normal regulation of the heart rate.

When a person is under medication for some other disease, the doctor may seek information about the current medication. It is observed that the use of medications for heart disease and high blood pressure, often leads to this condition. In such cases, altering the medications can treat the condition.

In addition, the doctor may prescribe arrhythmia medications for the regulation of normal heartbeat. The condition should be treated as soon as possible, as severe cases can lead to complications such as heart failure and stroke. It is always advisable to consult your physician in case of any change in the heart rate, so that proper diagnosis and treatment can be done at the right time. Even after treatment, if the symptoms of this condition persists, then he/she should report to the concerned physician for immediate medical attention.