Sick sinus syndrome
Sick sinus syndrome is a collection of heart rhythm disorders that include:
- Sinus bradycardia -- slow heart rates from the natural pacemaker of the heart
- Sinus pauses or arrest -- when the natural pacemaker of the heart stops working for periods of time
People with these disorders may also have other abnormal heart rhythms, such as:
- Atrial tachycardia -- fast heart rate that starts in the upper chambers of the heart (atria)
- Bradycardia-tachycardia -- alternating slow and fast heart rhythms
Bradycardia-tachycardia syndrome; Sinus node dysfunction
Causes, incidence, and risk factors
Sick sinus syndrome usually occurs in people older than 50. The cause is often scar-like damage to the heart's conduction system.
In children, a common cause of sick sinus syndrome is heart surgery, especially on the upper chambers.
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.
Tachycardias that start in the upper chambers of the heart may be part of the syndrome. These include atrial fibrillation, atrial flutter, and atrial tachycardia. A period of elevated heart rates is typically followed by very slow heart rates when the tachycardia ends.
Abnormal heart rhythms are often made worse by medications such as digitalis, calcium channel blockers, beta-blockers, and anti-arrhythmics.
Usually, no symptoms occur. Symptoms that do occur are may mimic those of other disorders.
Symptoms may include:
- Chest pain or angina
- Confusion or other changes in mental status
- Fainting or near-fainting
- Dizziness or light-headedness
- Sensation of feeling the heart beat (palpitations)
- Shortness of breath, possibly only with activity
Signs 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 occur 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 extremely slow heart rate 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 it may not be able to confirm the diagnosis.
Exercise testing has not been proven very effective as a screening tool.
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 medication 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).
A fast heart rate (tachycardia) may be treated with medications. Sometimes a procedure called radiofrequency ablation is used to cure tachycardia.
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.
- Decreased exercised capacity
- Fainting (syncope)
- Falls or injury caused by fainting
- Heart failure
- Poor heart pumping
Calling your health care provider
Call for an appointment with your health care provider if you experience spells of light-headedness, episodes of fainting, palpitations, or other symptoms.
Keeping your heart healthy by eating a well-balanced diet and exercising can prevent many types of heart disease.
It may help to treat related disorders. You may need to avoid some medications, based on your health care provider's advice.
Many times, the condition is not preventable.
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. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 64.
Last reviewed 6/4/2012 by David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Michael A. Chen, MD, PhD, Assistant Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.
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