What is Sick Sinus Syndrome?

Sick sinus syndrome is the term used to describe arrhythmic disorders caused by sinus node dysfunction. Considered a rare diagnosis, sick sinus syndrome adversely affects the electrical activity necessary for maintaining a normal heart rhythm. Depending on condition severity, treatment can range from a wait and monitor approach to the use of medication to manage one’s symptoms. Those whose condition proves unmanageable with medication or worsens may require a pacemaker. To ensure good prognosis, a timely diagnosis and appropriate treatment are essential.

A diagnosis of sick sinus syndrome is usually made once other conditions have been discounted. Establishing a correlation between symptoms and the type of arrhythmic episode is essential in making an accurate diagnosis. Tests designed to evaluate cardiovascular function, such as an electrocardiogram (ECG), are used to detect the presence and severity of an arrhythmia. If the arrhythmia is episodic, a portable monitor may be used to record the heart's rhythm, over a period of 24-48 hours, for analysis. Given they remain asymptomatic, meaning they experiences no symptoms, individuals with sick sinus syndrome are usually monitored over the long term.

Positioned in the upper atrium, the sinoatrial node (SA), or sinus node, functions to set the pace of one's heart rhythm. Most diagnoses of sick sinus syndrome are associated with the natural deterioration of the heart muscle that occurs with age. Medication use that may impair the heart's electrical conductivity over the long term can also contribute to the development of sick sinus syndrome. Other factors that may trigger symptoms include certain chronic conditions, including heart disease, and injury to the heart muscle as may be sustained during a heart attack or surgery.

How the sinus node misfires will determine the impact on one’s heart rhythm. A hypersensitive electrical impulse will generally induce an elevated heart rate, whereas a delayed impulse will trigger a slowed heart rate. A temporary disruption in electrical impulse delivery can cause a hesitation in one’s heartbeat, a condition known as sinus arrest. Those who demonstrate a delayed heart rate that is very pronounced are considered at greatest risk for sinus arrest.

Individuals with sick sinus syndrome will generally experience a gradual onset of signs and symptoms. Frequently, one will become easily fatigued or feel faint with minimal activity. Others may experience impaired cognition that may or may not be accompanied by heart palpitations and shortness of breath. If sick sinus syndrome remains undiagnosed, one’s chance for complications increases significantly. An irregular rhythm can place unnecessary stress on the heart, contributing to blood clot formation, stroke and heart failure.

Treatment approach is generally determined by the type and severity of one’s condition. Anti-arrhythmia medications may be used to re-establish and maintain a regular heart rhythm in individuals with an elevated heart rate, or tachycardia. If medications do not suffice in controlling one's tachycardia, additional treatment options may be explored, including pacemaker implantation.

Symptom progression associated with a decreased heart rate, known as bradycardia, often necessitates the implantation of a synthetic pacemaker to prevent heart failure. Condition severity will generally dictate the type of pacemaker implanted. Performed as a minimally invasive procedure, the pacemaker is positioned near the clavicle, or collarbone, and synched to support a normal rhythm. Risks associated with pacemaker placement can include infection, excessive bleeding, and nerve damage.