Sick Sinus Syndrome

Reference –

U.S. National Library of Medicine

July 18, 2016

Sick sinus syndrome

Sick sinus syndrome is a group of heart rhythm disorders that include:
  • Sinus bradycardia: This occurs when the natural pacemaker of the heart does not send out a signal telling the heart to beat often enough. The heart beat rate is slow.
  • Sinus pauses or arrest: This occurs when the natural pacemaker of the heart stops sending out signals telling to heart to beat for periods of time.

People with these disorders may also have other abnormal heart rhythms, such as:

  • Supraventricular tachycardia: This is a fast heart rate that starts in the upper chambers of the heart (atria).
  • Bradycardia-tachycardia: This is a pattern of alternating slow and fast heart rhythms (sometimes called “tachy-brady syndrome”).


Sick sinus syndrome most often occurs in people older than 50. It is often due to scar-like damage to electrical pathways in the heart muscle tissue.

In children, heart surgery on the upper chambers is a common cause of sick sinus syndrome.

Coronary artery disease, high blood pressure, and aortic and mitral valve diseases may occur with sick sinus syndrome, although these diseases may have nothing to do with the syndrome.

Sick sinus syndrome is uncommon. Sinus bradycardia occurs more often than the other types of the condition.

Tachycardias that start in the upper chambers of the heart may be part of the syndrome. These include atrial fibrillation, atrial flutter, atrial tachycardia, and other types of fast heart rates. A period of fast heart rates is often followed by very slow heart rates immediately after the tachycardia ends.

Some medicines can make abnormal heart rhythms worse. These include digitalis, calcium channel blockers, beta-blockers, and anti-arrhythmics.


Most of the time, there are not symptoms.

Symptoms that do occur may mimic those of other disorders.

Symptoms may include:

Exams and Tests

The heart rate may be very slow at any time. Blood pressure may be normal or low.

Sick sinus syndrome may cause symptoms of heart failure to start or get worse. Sick sinus syndrome is diagnosed when the symptoms occur only during episodes of arrhythmia. However, this is often hard to prove.

An ECG may show abnormal heart rhythms related to this syndrome.

Holter monitoring is an effective tool for diagnosing sick sinus syndrome. It may pick up very slow heart rates and long pauses, along with episodes of atrial tachycardias. Other forms of long-term electrical monitoring may also be useful.

An intracardiac electrophysiology study (EPS) is a very specific test for this disorder. However, it is not often needed and may not confirm the diagnosis.

Exercise testing has not been shown to work well to detect the problem.


You may not need treatment if you do not have any symptoms. Your doctor will review the medicines you take to make sure they are not making your condition worse. Do not stop taking any of your medicines unless your doctor tells you to do so.

You may need a permanent implanted pacemaker if your symptoms are related to bradycardia (slow heart rate).

PacemakerA fast heart rate (tachycardia) may be treated with medicine. Sometimes, a procedure called radiofrequency ablation is used to cure tachycardia.

In some cases, medicines used to control periods of fast heart rate are combined with use of a pacemaker, which guards against periods of slow heart rate.

Outlook (Prognosis)

The syndrome is progressive, which means it usually gets worse over time.

The long-term outlook is excellent for people who have a permanent pacemaker implanted.

Possible Complications

  • Angina
  • Decreased exercise capacity
  • Fainting (syncope)
  • Falls or injury caused by fainting
  • Heart failure
  • Poor heart pumping

When to Contact a Medical Professional

Call your health care provider if you have:

  • Light-headedness
  • Fainting
  • Palpitations
  • Other symptoms of the condition


Keeping your heart healthy by eating a well-balanced diet and exercising can prevent many types of heart disease.

You may need to avoid some types of medicines. Many times, the condition is not preventable.

Alternative Names

Bradycardia-tachycardia syndrome; Sinus node dysfunction


Olgin JE, Zipes DP. In: Specific arrhythmias: diagnosis and treatment. In: Bonow RO, Mann DL, Zipes DP, Libby P, Braunwald E, eds. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. St. Louis, MO: WB Saunders; 2011:chap. 39.

Zimetbaum P. Cardiac arrhythmias with supraventricular origin. In: Goldman L, Schafer AI, eds. Goldman’s Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 64.

Update Date 5/13/2014

Updated by: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

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About Dr Bode

Retired anesthesiologist. Little league shortstop and team MVP 1956, Newspaper delivery boy of the year at Long Beach Press Telegram 1959. St. Anthony High School Valedictorian 1964. Long Beach State University, Certificate of Excellence in General Chemistry. Long Beach State golf team 1967 - 1968. Graduate, UCLA School of Medicine 1972. Club Champion at Stevens Point Country Club, Wisconsin 1977. Chairman Department of Anesthesia, St. Michael's Hospital, Stevens Point, WI. Certified ACLS Instructor. President, Mendocino Lake County Medical Society 2002 - 2003. Disabled due to phlebitis with palpitations and arrhythmias 2005. Cardiovascular research 2005 to present. Member, American Heart Association, Heart Rhythm Society, California Society of Anesthesiologist, American Society of Anesthesiologists. President Willits Garden Club 2013 - 2015, Director, 2015 - 2017 Mendo-Lake District Garden Clubs

One thought on “Sick Sinus Syndrome

  1. The sick sinus syndrome involves a malfunction of the pacemaker of the heart, which is the SA node located inside the right atrium.

    Blood clots called venous thromboembolism (VTE) are the culprits that cause pacemaker malfunction when they get stuck in the tricuspid or pulmonary valves. VTE in the heart valves cause premature atrial or ventricular contractions depending on which valve is congested.

    Moreover, clots cause palpitations with different sensations as they pass through these dofferent valves.

    First, clots cause fast fluttering jugular pulsations in the neck veins when they go through the tricuspid valve. Next, they cause slow flip-flop sensations inside the heart when they go through the pulmonary valve.

    This is complicated physiology, and it will melt your brain if you think of everything at the same time. So look at one thing and take your time. Next, study something else. Gradually see the whole picture, which is the Gestalt.

    Try to connect the bloody dots that explain how tiny clots inside different heart valves cause tachycardia or bradycardia.

    Thanks for your interest in thrombophysiology, which explains how blood clots in the heart congests the valves and cause malfunction of the pacemaker. Clots speed up or slows down the heart depending on whether the clots clog up the tricuspid or pulmonary valve.

    All truths are easy to understand once they are discovered; the point is to discover them.

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