Changing Lifestyles, Changing Habits: What’s a Heart Arrhythmia?
Typically, the heart beats very regularly and steadily by contracting and relaxing. The heart has four chambers—two atria on the top and two ventricles on the bottom. In a normal situation, each heartbeat starts in the right atrium, where a bundle of cells called the “sinus node” send out an electrical signal. (The sinus node is often called the heart’s “natural pacemaker.”) This signal spreads to the area below the atria, called the AV node, and then to the ventricles below.
This electrical signal traveling through the heart is what causes the heart to beat. First the atria, the chambers on top, contract, pumping blood into the ventricles. Then the ventricles contract, pumping blood throughout the body. For most people, the whole heart contracts 60 to 100 times per minute. Each contraction equals one heartbeat. The average heart beats 100,000 times per day and pumps about 2,000 gallons daily.
But sometimes, the heartbeat becomes irregular. The beat may begin in a place in the heart other than the sinus node. The sinus node itself may develop an abnormal rhythm. Or the heart itself may have a block that makes the rhythm irregular. Situations like these are called “arrhythmias.”
Heart rhythms that are too fast are called “tachycardias.” Rhythms that are too slow are called “bradychardias.”
Symptoms and causes of arrhythmias
Symptoms of arrhythmia include
- Palpitations or rapid thumping in the chest
- Feeling tired or light-headed
- Passing out
- Shortness of breath
- Chest pain
It’s not always clear what the cause of an arrhythmia is. But possible causes include
- Heart disease
- Diet pills
- Cough and cold medicine
The American Heart Association notes that as people get older, their chances of experiencing arrhythmic beating of the heart increase.
Are arrhythmias serious?
Many arrhythmias are not serious. Sometimes, an arrhythmia happens once and never again. Other times, you can stop the behavior that causes the arrhythmia, such as coffee drinking, and that’s enough to stop the arrhythmia.
But there are some arrhythmias that can be very serious, even life-threatening. The most common serious arrhythmia is called “atrial fibrillation,” or AF. About 2 million Americans have this condition.
In cases of AF, the two small upper chambers of the heart, the atria, quiver instead of beating effectively. Blood is not pumped completely out of the atria when the heart beats. The heart beats too quickly or too slowly, and the beat is irregular. Blood that is left in the atria sometimes forms clots, which can cause a stroke by blocking blood flow to the brain. If you have AF, your chances of having a stroke are five times higher than someone who doesn’t have it.
If AF is severe enough and it isn’t treated, it can lead to chronic fatigue, congestive heart failure and other rhythm problems, in addition to stroke.
The most serious arrhythmia is called “ventricular fibrillation,” of VF. The ventricles quiver and cannot pump any blood. VF is a medical emergency. If it’s not treated immediately with electrical shock, death is almost certain.
Treatment for arrhythmias
Treatment for arrhythmias depends on the causes and the severity of the condition. It’s important for patients to work with their doctors and other members of their healthcare team to determine what changes they need to make in terms of nutrition, exercise and caffeine and alcohol intake. Frequently, medications are necessary too. And in some cases, pacemakers and other electrical devices are needed.
Read “The High Tech Heart” article in this month’s issue to find out what’s involved when you get a pacemaker.
The American Heart Association, Heart and Stroke A to Z Guide. National Heart Lung and Blood Institute of the National Institutes of Health
American College of Cardiology