The Beating Heart
Just about everyone experiences a skipped or extra beat now and again. And the symptoms that may accompany an extra beat, such as palpitations or dizziness, don't necessarily indicated the severity of the problem.
The heart is resilient. Yet the balance between the heart's electrical impulses, muscle contraction and blood flow is complex. Coronary artery disease, structural defects and other conditions can bring about an irregular heartbeat. Cardiac arrhythmias can make it difficult to enjoy life fully and can lead to heart attack, heart failure or sudden cardiac death.
Physicians who specialize in the treatment of cardiac rhythm disorders are called electrophysiologists.
The Heart's Electrical System
The sinus node is the heart's natural pacemaker, sending out 60 to 100 impulses a minute. The impulses spread through the upper chambers of the heart, causing them to contract. The impulse continues along a pathway to a second node that lies between the top and bottom halves of the heart. The AV node acts as a stop sign for the impulses, delaying them long enough for the lower chambers of the heart to fill with blood.
Once the lower chambers are full, the impulse travels to the bottom of the heart, across conducting fibers that branch left and right. Here they begin the contraction that propels blood from the lower chambers out to the body.
A failure anywhere along the electrical impulse's journey can result in an arrhythmia.
Diagnosing Heart Arrhythmias
The most common test used to detect cardiac arrhythmias is the EKG. This is a painless, non-invasive test in which electrodes are placed on the chest (and sometimes the back) to record the electrical activity of the heart as a series of wavy lines, or tracings. With their special knowledge and training, heart specialists are able to detect many rhythm abnormalities from these tracings.
Sometimes rhythm disturbances come and go and can't be picked up during a routine EKG. A Holter monitor can record the heartbeat for a specified period of time, increasing the likelihood of detecting the arrhythmia. Some patients may need to wear an event monitor for an extended period. Patients activate the recording device when they feel an arrhythmia.
An EP (electrophysiology) study is performed in a specially equipped cardiac catheterization lab by an electrophysiologist. During this study, the doctor maps the electrical pathways of the heart. As part of this study the physician may ablate (destroy) any abnormal pathways in order to relieve the arrhythmia.
Symptoms of Cardiac Arrhythmias
- Palpitations - described as missed beats, skips, thumps, butterflies, fluttering or racing.
- Dizziness - typically expressed as a sensation of falling rather than a sensation of spinning.
- Fainting or syncope - complete loss of consciousness with falling or physical collapse.
- Chest pain - often caused by the heart muscle growing tired after an extended period of rapid beating.
- Shortness of breath - the feeling of not being able to catch your breath.
One of the most commonly diagnosed cardiac arrhythmias is atrial fibrillation. Atrial fibrillation may be caused by a number of health conditions, most commonly high blood pressure, diabetes or coronary artery disease. It's also associated with heart failure, excessive alcohol use and lung disease. Occasionally, atrial fibrillation may occur following bypass surgery.
Atrial fibrillation by itself is not a"killer" disease, but its troublesome and sometimes frightening symptoms can interfere with a patient's quality of life. Because people with atrial fibrillation have a six-fold increase in the risk of stroke, it is important that those who are diagnosed, or at risk, of the disease, receive ongoing care and management.