Sick sinus syndrome
Sick Sinus Syndrome
Sick sinus syndrome is a type of arrhythmia. Symptoms ranging from dizziness to unconsciousness due to chaotic or absent atrial activity often with bradycardia alternating with tachycardia, recurring ectopic beats including escape beats, runs of supraventricular and ventricular arrhythmias, sinus arrest, and sinoatrial block.
Alternative Names: Sinus bradycardia, sinus node dysfunction, bradycardia-tachycardia syndrome.
Your heart is made up of four chambers — two atria and two ventricles. The rhythm of your heart is normally controlled by the sinoatrial node (SA node) — or sinus node — an area of specialized cells located in the right atrium. This natural pacemaker produces the electrical impulses that trigger each heartbeat. From the sinus node, electrical impulses travel across the atria to the ventricles, causing them to contract and pump blood out to your lungs and body.
A normal sinus node paces your resting heart between 60 and 100 beats a minute. If you have sick sinus syndrome, your sinus node isn't functioning properly, so your heart rate may be too slow (bradycardia) or too fast (tachycardia) or irregular.
Sick sinus syndrome is a generalized abnormality of cardiac impulse formation that may be caused by an intrinsic disease of the sinus node that makes it unable to perform its pacemaking function or by extrinsic causes. Abnormalities encompassed in this syndrome include sinus bradycardia, sinus arrest, combinations of sinoatrial and atrioventricular nodal conduction disturbances, and atrial tachyarrhythmias.
Sick sinus syndrome is not a specific disease, but a group of signs or symptoms that indicate the SA node is not functioning properly.
Sick sinus syndrome is characterized by sinus node dysfunction with an atrial rate inappropriate for physiologic requirements. Although the condition is most common in the elderly, it can occur in persons of all ages, including neonates. The mean age of patients with this condition is 68 years and both sexes are affected approximately equally.
The first sign an individual with SSS notices is a consistently slow heart rate or bradycardia. Often, the rate falls to 45 to 55 beats per minute or less before it is noticed.
Other symptoms may include:
Fatigue and weakness.
Shortness of breath.
Falls or injury caused by fainting.
Inadequate heart pumping.
Sick sinus syndrome may also be associated with tachycardias (fast heart rate) such as PSVT (paroxysmal supraventricular tachycardia) and atrial fibrillation. Tachycardias that occur with sick sinus syndrome are characterized by a long pause after the tachycardia. Abnormal rhythms are often caused or worsened by medications such as digitalis, calcium channel blockers, beta-blockers, sympatholytic medications, and antiarrhythmics.
Causes and Risk Factors:
Disorders that cause scarring, degeneration, or damage to the conduction system can cause sick sinus syndrome, including amyloidosis, sarcoidosis, Chagas' disease, and cardiomyopathies.
Sick sinus syndrome is more common in elderly adults, where the cause is often a nonspecific, scar-like degeneration of the conduction system.
Cardiac surgery, especially to the atria, is a common cause of sick sinus syndrome in children.
Coronary artery disease, high blood pressure, and aortic and mitral valve diseases may be associated with sick sinus syndrome, although this association may only be incidental.
Sick sinus syndrome can be hard to diagnose because you may not have many of the symptoms. Your doctor will take a medical history, ask about your symptoms, and listen to your heart with a stethoscope. Here is a list of other tests that your doctor may order.
A standard electrocardiogram (ECG or EKG), which is the best test for diagnosing arrhythmia. This test helps doctors analyze the electrical currents of your heart and determine the type of arrhythmia you have.
Holter monitoring, which gets a nonstop reading of your heart rate and rhythm over a 24-hour period. You wear a Holter monitor, which is connected to small metal disks called electrodes that are placed on your chest. With certain types of monitors, you can push a "record" button to capture a rhythm when you feel symptoms.
Event monitors, which are devices that record problems that may not be found within a 24-hour period. The devices used for this type of test are smaller than a Holter monitor. One such device is the size of a beeper, and another is worn like a wristwatch. As with Holter monitoring, you wear the recording device. When you feel the symptoms of an arrhythmia, you can telephone a monitoring station, where a record can be made. If you cannot get to a telephone during your symptoms, you can turn on the device's memory function. Later, you can send the recorded information to a monitoring station by using a telephone. These devices also work during episodes of fainting.
Electrophysiology studies (EPS), which are usually done in a cardiac catheterization laboratory. A long, thin tube called a catheter is inserted in an artery in your leg and guided to your heart. Electrical impulses from your heart are sent through the catheter and mapped out. This map helps doctors find out what kind of arrhythmia you have and whether it is caused by sick sinus syndrome.
Treatment for sick sinus syndrome focuses on eliminating or reducing unpleasant symptoms. In first step, your doctor may start by looking at your current medications to see if any of them could be interfering with the function of your sinus node. Medications used to treat high blood pressure or heart disease — such as beta blockers or calcium channel blockers — can worsen abnormal heart rhythms. In some cases, adjusting these medications can relieve symptoms. Anticoagulation will be needed for patients with atrial fibrillation.
Pacemaker therapy is the only effective surgical care for patients with chronic symptomatic Sick sinus syndrome. The major goal of pacemaker therapy in patients with SSS is to relieve symptoms. It is essential to document symptoms concurrent with the dysrhythmia when evaluating whether pacemaker placement will be beneficial. Artificial pacemakers are well tolerated in elderly patients.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
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