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Sick Sinus Syndrome

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Last updated January 14, 2021

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Sick sinus syndrome is a condition in which the normal pacemaker of the heart is unable to keep the heart beating at a normal rate to deliver blood to the body.

What is sick sinus syndrome?

Sick sinus syndrome is a condition in which the normal pacemaker of the heart is unable to keep the heart beating at a normal rate or rhythm to deliver blood to the body. Causes include replacement of pacemaker cells with aging, heart disease or heart attack, inflammation or infiltration of the heart, trauma, medications, toxins, abnormal electrolyte levels, and mutations in certain genes.

Symptoms include feeling lightheaded or passing out, fatigue, chest discomfort, a sensation of rapid or skipped beats, shortness of breath, sudden-onset numbness or weakness, and confusion or loss of consciousness.

The diagnosis is made by electrocardiography (EKG) or cardiac monitoring.

The best long-term treatment is implantation of an artificial pacemaker. Other treatments include medications to temporarily increase the pacing of the heart and medications to reduce the risk of developing a blood clot.

You should visit your primary care physician, where an ECG can measure the electrical rhythms of the heart and potentially identify Sick Sinus Syndrome. Otherwise, your doctor may use a longer term monitoring device. Treatment is only for severe cases and involves a pacemaker.

Sick sinus syndrome symptoms

Sick sinus syndrome can present with a few main symptoms and others that only occur in some people or very severe cases.

Main symptoms

The more common symptoms of sick sinus syndrome include:

  • Feeling lightheaded or about to pass out: This is the most common symptom in which you feel as though you may faint, also called syncope. This occurs in about 50 percent of patients. This happens when the heart is not beating fast enough to provide blood to the brain.
  • Feeling more tired than usual: This happens because your heart is not beating fast enough to provide blood to the rest of your body.
  • Chest discomfort: This can also be described as pain, and may be infrequent. It can eventually become more frequent and severe.

Other symptoms

Other symptoms of sick sinus syndrome that may be experienced include:

  • Rapid or "skipped" beats: This can be described as occasional feelings of a fluttering of the chest or a feeling of a skipped beat (palpitations). This occurs because the heart is not beating normally, and in some cases, sick sinus syndrome can be associated with other abnormal heart rhythms.
  • Shortness of breath, especially when active: During exercise or activity your body needs even more blood that the heart is not supplying fast enough.
  • Sudden-onset numbness or weakness: Some people can develop heart rhythm abnormalities that increase the risk of developing a blood clot in the heart, which can then travel to the brain and cause a stroke. This can cause sudden-onset numbness or weakness, usually on one side of the body.
  • Confusion or loss of consciousness: In severe cases, people with sick sinus syndrome can experience confusion or loss of consciousness. This occurs when the heart rate is too slow for a long period of time such that the brain is at risk of becoming damaged.

What causes sick sinus syndrome?

Sick sinus syndrome can involve abnormally slow heart rates, abnormally fast heart rates, or alternating fast and slow heart rates, known as "tachy-brady syndrome." Sick sinus syndrome usually affects older adults, with an average age of 68 years; sick sinus syndrome affects one in every 600 cardiac patients 65 years or older. Causes include a development of scar tissue in the heart, heart disease or heart attacks, disorders in heart function or heart trauma, certain medications, toxins or abnormal electrolyte levels, and genetic mutations.

Development of scar tissue

The most common cause of sick sinus syndrome is replacement of the normal pacemaker cells with scar tissue. This process can occur with aging, or after damage to the heart such as a heart attack.

Heart disease or heart attack

Heart disease or a heart attack (myocardial infarction) that affects the blood vessels bringing blood to the pacemaker cells can cause sick sinus syndrome. This will damage the pacemaker cells by not delivering enough oxygenated blood to them. This has been associated with up to 33 percent of cases of sick sinus syndrome.

Disorders in heart function or heart trauma

This includes inflammation of the heart, substances infiltrating the heart, and trauma to the heart that can all cause damage and lead to sick sinus syndrome.

  • Inflammation of the heart: This can be caused by diseases or various infections, such as rheumatic fever. This can happen after you get a strep throat infection that is not properly treated.
  • Substances infiltrating the heart: Some diseases involve abnormal substances that infiltrate the heart tissue and interfere with normal conduction. These include hemochromatosis, sarcoidosis, amyloidosis, and various autoimmune diseases.
  • Trauma to the heart: This can occur through an external injury or during the course of heart surgery.


Certain medications or toxins can decrease the activity of the pacemaker cells, including:

  • Calcium channel blockers: For high blood pressure
  • Beta blockers or digoxin: For heart disease
  • donepezil or rivastigmine: For Alzheimer's disease

Toxins and abnormal electrolyte levels

The presence or lack of the following in adequate levels can cause sick sinus syndrome.

  • Toxins: These include a toxin produced by some plants and found in certain types of honey.
  • Electrolyte abnormalities: This commonly includes high or low levels of potassium and low levels of calcium.

Genetic mutations

Rare mutations in certain genes can cause infants to be born with sick sinus syndrome. In these cases, sick sinus syndrome and other heart diseases usually run in the family. One example is a condition called Brugada syndrome, which can cause sudden cardiac death.

Treatment options and prevention for sick sinus syndrome

Sick sinus syndrome is a chronic condition that usually cannot be completely treated unless you undergo surgery to implant a permanent pacemaker. Therefore, initial treatments are focused on controlling and reducing symptoms. Treatment options include medication changes, additional prescriptions, or a pacemaker implant.

Medication changes

Your physician will review your medications to see if any of them could be causing or worsening your sick sinus syndrome. He or she may stop or reduce the dose of those medications to see if that improves your symptoms.

Medication to reduce the risk of developing a blood clot

Some people with sick sinus syndrome have associated heart rhythm abnormalities that increase their risk of developing a blood clot in the heart, which can then travel to the brain and cause a stroke. This occurs in more than 50 percent of patients. Your physician will review your risk of developing a blood clot and determine if you would benefit from taking a blood thinner such as warfarin (Coumadin) long-term to reduce your risk of developing a blood clot.

Medication to increase the pacing rate of the heart

Your physician or emergency responders can give a medication called atropine (Atropen) intravenously that temporarily increases the pacing rate of the heart if:

  • Your symptoms are prolonged or severe: Such as lightheadedness, confusion, loss of consciousness, chest pain, or shortness of breath.
  • It is an emergency situation: This medication is temporary until surgery can be done to implant an artificial pacemaker.

Procedure to implant an artificial pacemaker

The best long-term way to treat sick sinus syndrome that causes a slow heart rate is surgery involving the implant of an artificial pacemaker into the heart.

  • Details: An artificial pacemaker will be implanted into the heart. This device will take over as the pacemaker for the heart, in place of the improperly functioning natural pacemaker cells.
  • Efficacy: This will restore a normal rhythm to the heart and relieve most or all of the symptoms. Historically, sick sinus syndrome accounted for one-half of all pacemaker implantations.

When to seek further consultation for sick sinus syndrome

You should seek care from a physician if you suspect you have sick sinus syndrome or any time you lose consciousness for an unknown reason.

If you experience any symptoms of Sick Sinus Syndrome

You should see your physician if you experience chest discomfort or shortness of breath. Your physician can evaluate your medications to see if any of them might be causing sick sinus syndrome, as well as evaluate if you would benefit from receiving an artificial pacemaker.

If you feel confused or lose consciousness

Experiencing confusion or loss of consciousness may indicate that you are experiencing severe sick sinus syndrome that may put your brain at risk of being damaged. You should go to the emergency room or call an ambulance to potentially receive medications or a pacemaker to improve your heart rate.

Questions your doctor may ask to determine sick sinus syndrome

  • Any fever today or during the last week?
  • Have you ever been diagnosed with diabetes?
  • Do you have trouble sleeping?
  • Have you been feeling more tired than usual, lethargic or fatigued despite sleeping a normal amount?
  • Have you lost your appetite recently?

Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.

Hear what 1 other is saying
Foolish ManPosted January 23, 2020 by R.
Male 84, At 70 years old I retired to a 55+ community where I played pickle ball. Three or four times on my way home in my golf cart I felt dizzy and pulled over and passed out for a few seconds and didn’t tell anybody. My wife and I were on our way home from Michigan when I passed out at the wheel while on cruise control doing 75 mph. My wife held me up with her left hand and steered with her right hand until I woke up eight or nine seconds later and I pulled over. I found out my pulse rate was 42 and a pacemaker was implanted and it raised my rate to 60 bpm granting me more time with my loved ones. Oh foolish man that I was.

Dr. Liu received his medical degree from the University of Pennsylvania Perelman School of Medicine and is pursuing a career in ophthalmology. He graduated Phi Beta Kappa from Swarthmore College with a BA in biology. He has published research in multiple ophthalmology and healthcare journals and has received awards from Research to Prevent Blindness. In his free time, he enjoys running, biking, and spending time with his friends and family.

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