eart rhythm problems or heart arrhythmias, occur when the electrical impulses in your heart that coordinate your heartbeats don’t function properly, causing your heart to beat too fast, too slow or irregularly. Heart arrhythmias are common and usually harmless. Most people have occasional, irregular heartbeats that may feel like a fluttering or racing heart.
Doctors classify arrhythmias not only by where they originate (atria or ventricles) but also by the speed of heart rate they cause:
- Tachycardia (tak-ih-KAHR-de-uh). This refers to a fast heartbeat — a resting heart rate greater than 100 beats a minute.
- Bradycardia (brad-e-KAHR-de-uh). This refers to a slow heartbeat — a resting heart rate less than 60 beats a minute.
Not all tachycardias or bradycardias mean you have heart disease. For example, during exercise it’s normal to develop tachycardia as the heart speeds up to provide your tissues with more oxygen-rich blood.
Heart arrhythmias causes
Many things can lead to, or cause, an arrhythmia, including:
- Scarring of heart tissue (such as from a heart attack)
- Heart disease
- High blood pressure
- Overactive thyroid gland (hyperthyroidism)
- Excessive alcohol or caffeine intake
- Drug abuse
- Dietary supplements and herbal treatments
In a healthy person with a normal, healthy heart, it’s unlikely for a long-lasting arrhythmia to develop without some outside trigger, such as an electrical shock or the use of illicit drugs. That’s primarily because a healthy person’s heart is free from any conditions that cause an arrhythmia, such as an area of scarred tissue.
However, in a diseased or deformed heart, the heart’s electrical impulses may not travel through the heart properly, making arrhythmias more likely to develop.
Any heart condition that’s changed the structure of your heart can lead to arrhythmia development due to:
- An inadequate amount of blood. If blood supply to the heart is somehow reduced, this can alter the ability of heart tissue — including the cells that conduct electrical impulses — to function properly.
- Damage to or death of heart tissue. This can affect the way electrical impulses spread in the heart.
Changes in the structure of the heart may come from:
- Coronary artery disease (CAD). CAD causes the arteries in your heart to narrow, which can eventually cause a portion of the heart to die from a lack of blood flow (heart attack). A heart attack causes scarring of the heart tissue, which may make it so electrical impulses can’t travel normally through your heart to make it beat. This can cause the heart to beat dangerously fast (ventricular tachycardia) or to quiver (ventricular fibrillation).
- Cardiomyopathy. This occurs primarily when the walls in the lower half of your heart (ventricles) stretch and enlarge (dilated cardiomyopathy) or when the left ventricle wall thickens and constricts (hypertrophic cardiomyopathy). In either case, cardiomyopathy decreases your heart’s blood-pumping efficiency and often leads to heart tissue damage.
- Valvular heart diseases. Leaking or narrowing of your heart valves can lead to stretching and thickening of your heart muscle. When the chambers become enlarged or weakened due to the added stress caused by the tight or leaking valve, there’s an increased risk of developing an arrhythmia.
Certain factors may increase your risk of developing an arrhythmia. These include:
Age. With age, your heart muscle naturally weakens and loses some of its flexibility. This may affect how electrical impulses are conducted.
Genetics. Being born with a heart abnormality may affect your heart’s rhythm.
Thyroid problems. Your metabolism speeds up when your thyroid gland releases too many hormones. This may cause fast or irregular heartbeats and may be linked to atrial fibrillation. Your metabolism slows when your thyroid gland doesn’t release enough hormones, which may cause a bradycardia.
Drugs and supplements. Over-the-counter cough and cold medicines containing pseudoephedrine and certain prescription drugs may contribute to arrhythmia development.
High blood pressure. This increases your risk of developing coronary artery disease. It may also cause the walls of your left ventricle to thicken, which can change how electrical impulses travel through your heart.
Obesity. Along with being a risk factor for coronary artery disease, obesity may increase your risk of developing an arrhythmia.
Diabetes. Your risk of developing coronary artery disease and high blood pressure greatly increases with uncontrolled diabetes. In addition, episodes of low blood sugar (hypoglycemia) can trigger an arrhythmia.
Obstructive sleep apnea. This disorder, in which your breathing is interrupted during sleep, can cause bradycardia and bursts of atrial fibrillation.
Electrolyte imbalance. Substances in your blood called electrolytes, such as potassium, sodium, calcium and magnesium, help trigger and conduct the electrical impulses in your heart. Electrolyte levels that are too high or too low can affect your heart’s electrical impulses and contribute to arrhythmia development.
Alcohol consumption. Drinking too much alcohol can affect the electrical impulses in your heart or increase the chance of developing atrial fibrillation. In fact, development of atrial fibrillation after an episode of heavy alcohol intake is sometimes called “holiday heart syndrome.” Chronic alcohol abuse may cause your heart to beat less effectively and can lead to cardiomyopathy.
Caffeine or nicotine use. Caffeine, nicotine and other stimulants can cause your heart to beat faster and may contribute to the development of more serious arrhythmias. Illicit drugs such as amphetamines and cocaine may profoundly affect the heart and lead to many types of arrhythmias or to sudden death due to ventricular fibrillation.
Arrhythmias signs and symptoms
Some people do have noticeable arrhythmia symptoms, which may include:
- A fluttering in your chest
- A racing heartbeat (tachycardia)
- A slow heartbeat (bradycardia)
- Chest pain
- Shortness of breath
- Fainting (syncope) or near fainting
Noticeable signs and symptoms don’t always indicate a serious problem. Some people who feel arrhythmias don’t have a serious problem, while others who have life-threatening arrhythmias have no symptoms at all. Arrhythmias may cause you to feel premature heartbeats, or you may feel that your heart is racing or beating too slowly. Other signs and symptoms may be related to reduced blood output from your heart. These include shortness of breath or wheezing, weakness, dizziness, lightheadedness, fainting or near fainting, and chest pain or discomfort. Seek urgent medical care if you suddenly or frequently experience any of these signs and symptoms at a time when you wouldn’t expect to feel them.
Heart arrhythmia diagnosis
Heart monitoring tests specific to arrhythmias may include:
- Electrocardiogram (ECG). During an ECG, sensors (electrodes) that can detect the electrical activity of your heart are attached to your chest and sometimes to your limbs. An ECG measures the timing and duration of each electrical phase in your heartbeat.
- Holter monitor. This portable ECG device can be worn for a day or more to record your heart’s activity as you go about your routine.
- Event monitor. For sporadic arrhythmias, you keep this portable ECG device at home, attaching it to your body and using it only when you have symptoms of an arrhythmia. This lets your doctor check your heart rhythm at the time of your symptoms.
- Echocardiogram. In this noninvasive test, a hand-held device (transducer) placed on your chest uses sound waves to produce images of your heart’s size, structure and motion.
- Cardiac computerized tomography (CT) or magnetic resonance imaging (MRI). Although more commonly used to check for heart failure, these tests can be used to diagnose heart problems and to detect heart arrhythmias. In a cardiac CT scan, you lie on a table inside a doughnut-shaped machine. An X-ray tube inside the machine rotates around your body and collects images of your heart and chest.
- Stress test. Some arrhythmias are triggered or worsened by exercise. During a stress test, you’ll be asked to exercise on a treadmill or stationary bicycle while your heart activity is monitored by an ECG. If you have difficulty exercising, your doctor may use a drug to stimulate your heart in a way that’s similar to exercise.
- Tilt table test. Your doctor may recommend this test if you’ve had fainting spells. Your heart rate and blood pressure are monitored as you lie flat on a table. The table is then tilted as if you were standing up. Your doctor observes how your heart and the nervous system that controls it respond to the change in angle.
- Electrophysiologic testing and mapping. In this test, thin, flexible tubes (catheters) tipped with electrodes are threaded through your blood vessels to a variety of spots within your heart. Once in place, the electrodes can map the spread of electrical impulses through your heart. In addition, your cardiologist can use the electrodes to stimulate your heart to beat at rates that may trigger — or halt — an arrhythmia. This allows your doctor to see the location of the arrhythmia and what may be causing it.
If you have an arrhythmia, treatment may or may not be necessary. Usually it’s required only if the arrhythmia is causing significant symptoms or if it’s putting you at risk of a more serious arrhythmia or arrhythmia complication. If slow heartbeats (bradycardias) don’t have a cause that can be corrected — such as low thyroid hormone levels or a drug side effect — doctors often treat them with a pacemaker. A pacemaker is a small, battery-powered device that’s usually implanted near your collarbone. One or more electrode-tipped wires run from the pacemaker through your blood vessels to your inner heart. If your heart rate is too slow or if it stops, the pacemaker sends out electrical impulses that stimulate your heart to beat at a steady, proper rate.
For fast heartbeats (tachycardias), treatments may include one or more of the following:
Vagal maneuvers. You may be able to stop an arrhythmia that begins above the lower half of your heart (supraventricular tachycardia, or SVT) by using particular maneuvers that include holding your breath and straining, dunking your face in ice water, or coughing. Your doctor may be able to recommend other maneuvers to halt a fast heartbeat. These maneuvers affect the nervous system that controls your heartbeat (vagal nerves), often causing your heart rate to slow.
Medications. Many types of tachycardias respond well to anti-arrhythmic medications. Though they don’t cure the problem, they can reduce episodes of tachycardia or slow down the heart when an episode occurs. Some medications can slow down your heart so much that you may need a pacemaker. It’s very important to take any anti-arrhythmic medication exactly as directed by your doctor, in order to avoid complications.
Cardioversion. If you have a tachycardia that starts in the top half of your heart (atria), including atrial fibrillation, your doctor may use cardioversion, which is an electrical shock used to reset your heart to its regular rhythm. Usually this is done externally in a monitored setting, and you’re given medication to relax you during the procedure, so there’s no pain involved.
Ablation Therapy. In this procedure, one or more catheters are threaded through your blood vessels to your inner heart. They’re positioned on areas of your heart that your doctor believes are the sources of your arrhythmia. Electrodes at the catheter tips are heated with radiofrequency energy. Another method involves cooling the tips of the catheters, which freezes the problem tissue. Either method destroys (ablates) a small spot of heart tissue and creates an electrical block along the pathway that’s causing your arrhythmia. Usually this stops your arrhythmia.
Treatment for heart arrhythmias also may involve use of an implantable device:
Pacemaker. A pacemaker is an implantable device that helps regulate slow heartbeats (bradycardia). A small battery-driven device is placed under the skin near the collarbone in a minor surgical procedure. An insulated wire extends from the device to the right side of the heart, where it’s permanently anchored.
If a pacemaker detects a heart rate that’s too slow or no heartbeat at all, it emits electrical impulses that stimulate your heart to speed up or begin beating again. Most pacemakers have a sensing device that turns them off when your heartbeat is above a certain level. It turns back on when your heartbeat is too slow. Most people stay in the hospital one to two days after a pacemaker is implanted.
Implantable cardioverter-defibrillator (ICD). Your doctor may recommend this device if you’re at high risk of developing a dangerously fast or quivering heartbeat in the lower half of your heart (ventricular tachycardia or ventricle fibrillation). Implantable defibrillator units designed to treat quivering in the upper half of your heart (atrial fibrillation) also are available.
An ICD is a battery-powered unit that’s implanted near the left collarbone. One or more electrode-tipped wires from the ICD run through veins to the heart. The ICD continuously monitors your heart rhythm. If it detects a rhythm that’s too slow, it paces the heart as a pacemaker would. If it detects VT or VF, it sends out low- or high-energy shocks to reset the heart to a normal rhythm. An ICD may lessen your chance of having a fatal arrhythmia, compared with the use of medications.
In some cases, surgery may be the recommended treatment for heart arrhythmias:
Maze procedure. This involves making a series of surgical incisions in the upper half of your heart (atria). These heal into carefully placed scars in the atria that form boundaries that force electrical impulses in your heart to travel properly to cause the heart to beat efficiently. The procedure has a high success rate, but because it requires open-heart surgery, it’s usually reserved for people who don’t respond to other treatments. The surgeon may use a cryoprobe — an instrument for applying extreme cold to tissue — or a hand-held radiofrequency probe, rather than a scalpel, to create the scars.
Ventricular aneurysm surgery. In some cases, a bulge (aneurysm) in a blood vessel leading to the heart is the cause of an arrhythmia. If catheter ablation and implanted ICD don’t work, you may need this surgery. It involves removing the aneurysm that’s causing your arrhythmia. By removing the source of the abnormal impulses, the arrhythmia often can be eliminated.
Coronary bypass surgery. If you have severe coronary artery disease in addition to frequent ventricular tachycardia, your doctor may recommend coronary bypass surgery. This may improve the blood supply to your heart and reduce the frequency of your ventricular tachycardia.