Arrhythmias

How Arrhythmias Develop

The heart’s beating becomes irregular when the sinus node—the group of heart cells that generate the electrical signal that triggers the heart’s contraction—malfunctions or the signal is disrupted before it makes its way through the heart muscle. Arrhythmias can also occur when another group of cells takes over the function of the sinus node. Arrhythmias can affect both the upper chambers, or atria, and the lower chambers, or ventricles.

Types of Arrhythmias

There are various types of arrhythmias, which range from benign to those that can have serious consequences. Symptoms of each type are similar, and can include palpitations, rapid irregular heart rate, chest pain, shortness of breath, fatigue, lightheadedness and fainting. Any intense or persistent symptoms warrant medical attention.

• Atrial fibrillation is the most common type of arrhythmia, affecting nearly two million Americans. In atrial fibrillation, the atria beat in a rapid, unorganized rhythm. The heart can beat out of control at a rate of 150 to 200 beats per minute—well above the normal heart rate range of 60 to 100 beats per minute. Atrial fibrillation isn’t life-threatening, but it can lead to other health problems, including chronic fatigue and congestive heart failure. Sometimes a clot forms from blood that pools in the left atrium due to the atrium’s inability to empty blood completely into the left ventricle. If this clot enters the bloodstream and travels to the brain, it can block an artery and cause a stroke. People with atrial fibrillation have an increased risk of stroke.
• Atrial flutter is a fast heartbeat that originates most commonly in the upper right atrium. The condition is the result of an abnormality with the heart’s electrical pumping system. During atrial flutter, electrical activity doesn’t start with the sinus node as it should, but rather begins in another large circuit. This causes the atria to beat very rapidly—at a regular rate of 150 to 300 beats per minute.
• Supraventricular tachycardia refers to a fast, abnormal heart rhythm that involves both the atria and ventricles of the heart. The electrical problem originates either in the atria or an area in the middle region of the heart.
• Bradycardia is an abnormally slow heartbeat, usually less than the normal range of 60 to 100 beats per minute, resulting from an abnormality in the heart’s electrical pumping system.
• Ventricular tachycardia is characterized by a fast, steady abnormal heart rhythm coming from one of the ventricles. It is more serious than supraventricular tachycardia and can be life-threatening.
• Ventricular fibrillation is characterized by an irregular, fast heartbeat coming from one of the two ventricles. It is extremely serious. Because it prevents the heart from functioning and pumping adequately, it can lead to sudden death without emergency medical attention.
• Heart block is a term for a group of abnormally slow heart rhythms caused by different degrees of blockage as the electrical signal travels from the atrium to the ventricle. In first-degree heart block, the signal takes a little longer that average, producing a slower than average heartbeat. In second-degree heart block, the signal travels even more slowly, resulting in an even slower beat while in a third-degree heart block, the signal does not reach the ventricle at all. While a first-degree heart block may not cause symptoms, a second-degree block may produce troubling symptoms, and a third-degree heart block can be life-threatening.

Diagnosing Arrhythmias

Tests used to diagnose arrhythmias include:

• Electrocardiogram (ECG or EKG), either a standard ECG or a Holter monitor
• Stress test
• Electrophysiology studies (EPS)

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Treating Arrhythmias

Because arrhythmias usually cause few, if any, problems, they may not require treatment. However, when an arrhythmia causes symptoms, cardiologists may decide on one of the following options for treatment, based on the type of arrhythmia, the severity of symptoms and the presence of other medical conditions that can affect the course of the treatment.

• Lifestyle modification. Eliminating caffeine, alcohol or other substances believed to be causing the problem may relieve an arrhythmia. Stress-reduction measures such as meditation, stress-management classes, exercise programs or psychotherapy may also help.
• Medication. There are various types of drugs that may be used to treat arrhythmias. The choice of medication will be based on the type of arrhythmia, other conditions that may be present and other medicines the patient may be taking.
• Cardioversion. In this procedure, an electrical shock is delivered to the heart through the chest to stop very fast arrhythmias such as atrial fibrillation, supraventricular tachycardia or atrial flutter. The patient is connected to an ECG monitor that is also connected to the defibrillator. The electrical shock is delivered at a precise point during the ECG cycle to convert the rhythm to a normal one.
• Ablation. This procedure is performed in an operating-room environment. A catheter is inserted into a vessel in the groin and guided to the region of the heart from which the arrhythmia originates. Then high-frequency radio waves are focused through the catheter, destroying the heart cells responsible for the arrhythmia.
• Pacemaker. A permanent pacemaker is a small device that is implanted under the skin, usually in the shoulder area just under the collarbone, and sends electrical signals to start or regulate a slow heartbeat. A permanent pacemaker may be used to help the heart beat normally if the sinus node is not functioning properly or if electrical pathways are blocked. Pacemakers are typically used for slow arrhythmias such as bradycardia or heart block.
• Implantable cardioverter defibrillator. An implantable cardioverter defibrillator (ICD) is a small device, similar to a pacemaker, that is implanted under the skin, most often in the shoulder area just under the collarbone. An ICD senses the rate of the heartbeat. When the heart rate exceeds a rate programmed into the device, it delivers a small electrical shock to the heart to slow the heart rate. Many newer ICDs are combined with a pacemaker to deliver an electrical signal to regulate a heart rate that is too slow. ICDs are used for fast arrhythmias such as ventricular tachycardia or ventricular fibrillation.
• Surgery. Surgical treatment for arrhythmias is usually done only when all other appropriate options have failed. Surgical ablation is a major surgical procedure requiring general anesthesia. The chest is opened, exposing the heart. The site of the arrhythmia is located, and the tissue is destroyed or removed in order to eliminate the source of the arrhythmia.

Nutrition and Prevention

Reference these links for information on how to prevent heart disease and how to live a healthy lifestyle.

• Lifestyle Changes
• Exercise
• Healthy Diet
• Reduce Stress
• Stop Smoking
• Healthy Cholesterol Levels
• Reduce Sodium