Feb 11, 2011 Jennifer Houlahan
Sick Sinus Syndrome Overview: Symptoms, Risk Factors and Treatment – wpclipart.comHave you been diagnosed with sick sinus syndrome? Read on to learn more about the disease, treatment options, and hear a real patient’s perspective. 
Introduction to Sick Sinus Syndrome and Anatomy of the Heart
Sick sinus syndrome is a collection of heart rhythm disorders including unnaturally slow heart rates – known as bradycardia, unnaturally fast heart rates – known as tachycardia, and alternating slow and fast heart rates – known as bradycardia-tachycardia (1). these rhythm disorders are caused by a defect in the sinoatrial (SA) node of the heart. the SA node is located in the upper right chamber (atrium) of the heart and is composed of specialized pacemaker cells that allow it to set the inherent rhythm of the heart’s contractions or beats.
Every normal heart is composed of four chambers – two upper (the atria) and two lower (the ventricles). As previously stated, the rhythm of the heartbeat is controlled by the SA node which produces electrical signals that trigger the initiation of each heartbeat. after reaching the SA node, these electrical impulses continue across the atria to the ventricles, causing the heart to pump blood to your lungs and the rest of your body. Typically a healthy resting heart rate is between 60 and 100 beats per minute.
There are three types of sick sinus syndrome:
- Sinoatrial block occurs when electrical signals move too slowly through the sinus node causing bradycardia (heart rate below 60 beats per minute).
- Sinus arrest occurs when the electrical conduction activity of the sinus node pauses.
- Bradycardia-tachycardia syndrome occurs when the heart rate alternates between abnormally fast and slow rhythms, often pausing between heart beats.
Risk Factors
Sick sinus syndrome is relatively uncommon and although it can affect individuals of all ages, it typically manifests in older adults. the syndrome may be caused by one or more of the following factors:
- Chronic conditions affecting the heart muscle (myocardium) such as coronary artery disease, high blood pressure, heart valve disease, and muscular dystrophy.
- Diseases that cause scarring or other damage to the heart’s electrical conduction system.
- Medications such as calcium channel blockers or beta blockers often used to treat high blood pressure or other heart conditions.
Despite the aforementioned risk factors, sick sinus syndrome is most often caused by simple wear and tear to the heart muscle that may occur over time (2).
Symptoms
Some individuals with sick sinus syndrome are asymptomatic and do not experience any symptoms. others may experience nonspecific indicators that mimic other disorders (3). the key to identifying sick sinus syndrome is that bodily symptoms occur only when the heart is beating abnormally. Symptoms include:
- Chest pain or angina
- Confusion
- Fainting
- Dizziness
- Heart palpitations
- Shortness of breath
Complications
When the SA node is malfunctioning, it may lead to a dangerously slow heart rate that can cause fainting (syncope). Though it is uncommon, long periods of very slow or very fast heartbeats prevent the heart from providing bodily tissues with sufficient volumes of blood which in turn may result in heart failure. Individuals with bradycardia-tachycardia syndrome may be at an increased risk of developing blood clots within the heart that may migrate and cause a stroke. these blood clots develop because bradycardia-tachycardia syndrome is often accompanied by atrial fibrillation (quivering) which allows blood to pool within the chambers (4). Aspirin or Coumadin (Warfarin) are often prescribed to such patients in order to thin the blood and prevent blood clot formation thereby lowering the risk of stroke.
Tests and Diagnosis
In order to diagnose sick sinus syndrome, it is essential to establish a link between bodily symptoms and an abnormal heart rhythm. the most common and accurate test of heart function is the electrocardiogram (ECG). Typically physicians will first test patients on the standard ECG. however, as the standard ECG test lasts less than a minute, sick sinus syndrome symptoms may not be detected. Therefore, patients are often sent home with a Holter monitor ECG or event recorder ECG.
A Holter monitor ECG is a portable device that is carried in a pocket, attached to a belt, or linked to a shoulder strap. it records continuous heart activity for a minimum of twenty-four hours and up to two or more weeks, providing physicians with a complete picture of the patient’s heart rhythms. an event recorder ECG is also a portable device worn for variable amounts of time; however, it does not record continuously (5). Instead, the patient activates the recorder with the push of a button when he or she is experiencing symptoms. the event recorder is particularly helpful in assisting physicians with a proper diagnosis of sick sinus syndrome.
Treatment
The purpose of sick sinus syndrome treatment is to eliminate or reduce bothersome and/or life-threatening symptoms. As some individuals experience only minor symptoms, they may feel comfortable forgoing treatment while under routine doctor supervision. others who are bothered by their symptoms are typically treated with medication, implanted electronic pacemakers, or a combination of the two.
As previously stated, certain medications used to treat cardiovascular conditions such as high blood pressure or heart disease may exacerbate the symptoms of sick sinus syndrome. Therefore, a physician will perform a thorough evaluation of all current medications to determine whether any of them, particularly beta blockers and calcium channel blockers, are having a negative effect on the rhythm of the heart.
Surprisingly, these medications are also prescribed to treat the symptoms of sick sinus syndrome when patients suffer from dangerous periods of tachycardia. As previously mentioned, it is also standard practice for many patients to take some form of blood thinner, typically Aspirin or Coumadin (Warfarin), in order to reduce the risk of stroke from blood pooling during atrial fibrillation (quivering).
Most individuals with sick sinus syndrome will eventually require an internally implanted electronic pacemaker which is a small battery-powered device that assists the heart in maintaining a normal heart rhythm. Pacemaker implantation is a relatively simple outpatient procedure in which a doctor inserts the small device underneath the skin near the collarbone.
A Patient’s Perspective
61-year-old Judy Miller was first diagnosed with sick sinus syndrome in April of 2009. she had experienced occasional symptoms over the years prior to her diagnosis but hadn’t thought much of it. Then on a routine visit to the National Institutes of Health to donate platelets, the intake nurse noted her irregular heartbeat and recommended that she seek an emergency medical evaluation to determine the cause.
After a short hospitalization, much testing, and doctor supervised medication adjustment, Judy says that she “feels almost like her old self again”. currently she is being treated with a low-dose beta blocker and prophylactic aspirin. As she suffers from bradycardia-tachycardia syndrome, her symptoms typically “feel like racing heart beats interspersed with long pauses”. during these spells she often experiences fatigue and mental distraction, and occasionally feels faint.
Thanks to her medication, Judy’s symptomatic spells have reduced from as many as 10-15 a month down to 1-3. Though the beta blocker medication causes notable fatigue, she continues to lead an active life working, socializing with friends, taking frequent walks, biking long distances, and doing work around her house. Judy and her cardiologist have discussed the likelihood that she will need an implanted pacemaker later in life and she feels comfortable with this prospect provided it allows her to maintain her high quality of life.
(1) National Center for Biotechnology Information. “Sick sinus syndrome: Bradycardia-Tachycardia Syndrome; Sinus Node Dysfunction,” last reviewed: May 4, 2010. ncbi.nlm.nih.gov/pubmedhealth/PMH0001214.
(2) Mayo Clinic. "Sick Sinus Syndrome: Risk Factors," last modified November 5, 2010. mayoclinic.com/health/sick-sinus-syndrome/DS00930/DSECTION=risk-factors.
(3) National Institutes of Health. “Sick Sinus Syndrome,” Lat modified January 25, 2011.
nlm.nih.gov/medlineplus/ency/article/000161.htm.
(4) Mayo Clinic. “Sick Sinus Syndrome: Complications,” last modified May 23, 2009. mayoclinic.com/health/sick-sinus-syndrome/DS00930/DSECTION=complications.
(5) Mayo Clinic. “Sick Sinus Syndrome: Tests and Diagnosis,” last modified May 23, 2009. mayoclinic.com/health/sick-sinus-syndrome/DS00930/DSECTION=tests%2Dand%2Ddiagnosis.
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Sick Sinus Syndrome Overview: Symptoms, Risk Factors and Treatment – wpclipart.com