What is Sick Sinus Syndrome?
Sick Sinus Syndrome is a disorder characterized by an abnormal heart rhythm that occurs due to sinus node dysfunction. The sinus node is a natural pacemaker located in the right chamber (atrium) of the heart. It is responsible for electrical impulse transmission to maintain the normal rhythm and functioning of the heart.
In sick sinus syndrome, the malfunctioning of the sinus node produces irregularly paced electrical signals that makes the heart beat too fast or too slow, or to be interrupted by long pauses or an alternating combination of these rhythm issues.
Causes of Sick Sinus Syndrome
There are two distinctive factors affecting sinus node function:
Intrinsic Factors- These are internal factors of the heart leading to sinus node dysfunction.
- Age-related degeneration of the SA node
- Congenital disorder
- Arrhythmias (abnormal heart beat)
- Infiltrative cardiomyopathy (deposition of abnormal substances within the heart tissue)
- History of cardiac surgery
- Heart failure
- Metastatic cancer
- Damage to SA node or the sinus nodal artery after cardiothoracic surgery
- Infections such as bacterial endocarditis
Extrinsic Factors-These are external factors that can affect the pacing function of the SA node.
- Conditions that cause abnormally increased vagal tone such as carotid sinus hypersensitivity and vasovagal syncope
- Metabolic disorders such as hypothyroidism, hyperkalemia, hypokalemia, hypocalcemia, hypoxia, and hypothermia
- Obstructive sleep apnea
- Increased intracranial pressure (Cushing’s reflex)
- Certain medications and toxic substances
Risk factors for Sick Sinus Syndrome
Sick sinus syndrome is relatively uncommon. This condition can be seen in any age, but it is most commonly seen in people in their 70’s or older. Other common factors which might increase the risk of sick sinus syndrome include:
- High blood pressure
- High cholesterol
- Obesity
- Type 2 diabetes
- Sedentary lifestyle
- Smoking
- Alcohol addiction
- Long term medications
- Stress
Symptoms of Sick Sinus Syndrome
Signs and symptoms of sick sinus syndrome may include:
- Palpitations (rapid and fluttering heartbeats)
- Chest pain or discomfort
- Confusion
- Dizziness
- Fainting
- Fatigue
- Shortness of breath
- Bradycardia (Slow pulse)
Diagnosis of Sick Sinus Syndrome
Sick sinus syndrome symptoms are similar to other heart diseases, so your healthcare provider may order tests to confirm your diagnosis based on your history such as:
- An electrocardiogram (ECG)
- Treadmill test (stress test)
- A Holter monitor, a recorder that you have to wear over 24-48 hours which continuously records heart activity
- An event recorder, a portable device that can be activated to record heart activity when you experience symptoms
- Electrophysiologic (EP) testing, a hospital procedure which involves threading catheters into your heart through a vein in your thigh
- An echocardiogram (ECHO)or an ultrasound of your heart, to rule out structural heart problems
Treatment of Sick Sinus Syndrome
If Sick Sinus Syndrome symptoms are mild or infrequent and are not affecting your quality of life, then your health care provider may simply recommend regular health checkups to monitor your condition. Most people with significant symptoms may require further interventions such as:
Medications
Your healthcare provider will review your regular medications, including those used to treat high blood pressure or heart disease, which may interfere with sinus node function and adjust them or prescribe different ones as needed. Your healthcare provider may also prescribe other medications that might be needed to prevent or to slow down fast heartbeats.
Surgical Interventions
Most people with sick sinus syndrome eventually need a permanent device to control the heart rhythm known as pacemaker. A pacemaker is a small, battery-powered device that can be implanted under the skin of the collarbone with a minor surgical procedure. The pacemaker stimulates (paces) the sinus node electrical impulses and heart coordination as required to keep the rhythm regular. Your healthcare provider may consider implanting a pacemaker for you depending on the results of electrocardiograms (ECGs), your overall health and the risk of complications.
The type of pacemaker that will be chosen for you by your doctor depends on the type of irregular heart rhythm you have. Generally, the various types of pacemakers include:
- Single chamber pacemaker- This type usually carries electrical signals to the right lower heart chamber (ventricle) of the heart.
- Dual chamber pacemaker- This type stimulates the right lower heart chamber (ventricle) and the right upper heart chamber (atrium) separately.
- Biventricular pacemaker-This type is for people who have heart failure and heartbeat problems. The pacemaker stimulates both lower heart chambers (the right and left ventricles) to make the heart beat more efficiently.
Cardiac Ablation
Cardiac ablation is a catheter-based procedure to correct or control the heart rhythm. In this procedure, heat or cold energy is used to create tiny scars in the heart to block faulty signals and restore a regular heartbeat. It's most often done using thin, flexible tubes called catheters inserted through the veins or arteries.
Complications of Sick Sinus Syndrome
Complications of sick sinus syndrome include:
- Atrial fibrillation (irregular rapid heartbeat)
- Heart failure
- Stroke
- Cardiac arrest
- Multiple organ failure
- Prevention of Sick Sinus syndrome
- Healthy lifestyle changes that may help to avoid sick sinus syndrome:
- Quit smoking and alcohol
- Keep cholesterol and blood pressure under control
- Eat a heart-healthy diet
- Maintain a healthy weight
- Exercise regularly
- Avoid stress
