What is an Arrhythmia?
Heart rhythm problems (heart arrhythmias) occur when the electrical impulses that coordinate your heartbeats don’t work properly, causing your heart to beat too fast, too slow, or irregularly.
Types of arrhythmias
Doctors classify arrhythmias not only by where they originate (atria or ventricles) but also by the speed of heart rate they cause:
- Tachycardia This refers to a fast heartbeat — a resting heart rate greater than 100 beats a minute.
- Bradycardia 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 a fast heartbeat as the heart speeds up to provide your tissues with more oxygen-rich blood. During sleep or times of deep relaxation, it’s not unusual for the heartbeat to be slower.
Tachycardias originating in the atria include:
- Atrial fibrillation. Atrial fibrillation is a rapid heart rate caused by chaotic electrical impulses in the atria. These signals result in rapid, uncoordinated, weak contractions of the atria.
The chaotic electrical signals bombard the AV node, usually resulting in an irregular, rapid rhythm of the ventricles. Atrial fibrillation may be temporary, but some episodes won’t end unless treated.
Atrial fibrillation is associated with serious complications such as stroke.
- Atrial flutter. Atrial flutter is similar to atrial fibrillation. The heartbeats in atrial flutter are more-organized and more-rhythmic electrical impulses than in atrial fibrillation. Atrial flutter may also lead to serious complications such as stroke.
- Supraventricular tachycardia. Supraventricular tachycardia is a broad term that includes many forms of arrhythmia originating above the ventricles (supraventricular) in the atria or AV node. These types of arrhythmias seem to cause sudden episodes of palpitations that begin and end abruptly.
- Wolff-Parkinson-White syndrome. In Wolff-Parkinson-White syndrome, a type of supraventricular tachycardia, there is an extra electrical pathway between the atria and the ventricles, which is present at birth. However, you may not experience symptoms until you’re an adult. This pathway may allow electrical signals to pass between the atria and the ventricles without passing through the AV node, leading to short circuits and rapid heartbeats.
Tachycardias occurring in the ventricles include:
- Ventricular tachycardia. Ventricular tachycardia is a rapid, regular heart rate that originates with abnormal electrical signals in the ventricles. The rapid heart rate doesn’t allow the ventricles to fill and contract efficiently to pump enough blood to the body. Ventricular tachycardia may not cause serious problems if you have an otherwise healthy heart, but it can be a medical emergency that requires prompt medical treatment if you have heart disease or a weak heart.
- Ventricular fibrillation. Ventricular fibrillation occurs when rapid, chaotic electrical impulses cause the ventricles to quiver ineffectively instead of pumping necessary blood to the body. This serious problem is fatal if the heart isn’t restored to a normal rhythm within minutes.
Most people who experience ventricular fibrillation have underlying heart disease or have experienced serious trauma.
- Long QT syndrome. Long QT syndrome is a heart disorder that carries an increased risk of fast, chaotic heartbeats. The rapid heartbeats, caused by changes in the electrical system of your heart, may lead to fainting, and can be life-threatening. In some cases, your heart’s rhythm may be so erratic that it can cause sudden death.
You can be born with a genetic mutation that puts you at risk of long QT syndrome. In addition, several medications may cause long QT syndrome. Some medical conditions, such as congenital heart defects, may also cause long QT syndrome.
Bradycardia A slow heartbeat :
Although a heart rate below 60 beats a minute while at rest is considered bradycardia, a low resting heart rate doesn’t always signal a problem. If you’re physically fit, you may have an efficient heart capable of pumping an adequate supply of blood with fewer than 60 beats a minute at rest.
In addition, certain medications used to treat other conditions, such as high blood pressure, may lower your heart rate. However, if you have a slow heart rate and your heart isn’t pumping enough blood, you may have one of several bradycardias, including:
- Sick sinus syndrome. If your sinus node, which is responsible for setting the pace of your heart, isn’t sending impulses properly, your heart rate may alternate between too slow (bradycardia) and too fast (tachycardia). Sick sinus syndrome can also be caused by scarring near the sinus node that’s slowing, disrupting or blocking the travel of impulses. Sick sinus syndrome is most common among older adults.
- Conduction block. A block of your heart’s electrical pathways can occur in or near the AV node, which lies on the pathway between your atria and your ventricles. A block can also occur along other pathways to each ventricle.
Depending on the location and type of block, the impulses between the upper and lower halves of your heart may be slowed or blocked. If the signal is completely blocked, certain cells in the AV node or ventricles can make a steady, although usually slower, heartbeat.
Some blocks may cause no signs or symptoms, and others may cause skipped beats or bradycardia.
Although it often feels like a skipped heartbeat, a premature heartbeat is actually an extra beat. Even though you may feel an occasional premature beat, it seldom means you have a more serious problem. Still, a premature beat can trigger a longer-lasting arrhythmia especially in people with heart disease. Frequent premature beats that last for several years may lead to a weak heart.
Premature heartbeats may occur when you’re resting or may sometimes be caused by stress, strenuous exercise, or stimulants, such as caffeine or nicotine.
Certain conditions can lead to, or cause, an arrhythmia, including:
- A heart attack that’s occurring right now
- Scarring of heart tissue from a prior heart attack
- Changes to your heart’s structure, such as from cardiomyopathy
- Blocked arteries in your heart (coronary artery disease)
- High blood pressure
- Overactive thyroid gland (hyperthyroidism)
- Underactive thyroid gland (hypothyroidism)
- Sleep apnoea
- Infection with COVID-19
Other things that can cause an arrhythmia to include:
- Drinking too much alcohol or caffeine
- Drug abuse
- Stress or anxiety
- Certain medications and supplements, including over-the-counter cold and allergy drugs and nutritional supplements
Arrhythmias may not cause any signs or symptoms. In fact, your doctor might find you have arrhythmia before you do, during a routine examination. Noticeable signs and symptoms don’t necessarily mean you have a serious problem, however.
Noticeable arrhythmia symptoms may include:
- A fluttering in your chest
- A racing heartbeat (tachycardia)
- A slow heartbeat (bradycardia)
- Chest pain
- Shortness of breath
Other symptoms may include:
- Light-headedness or dizziness
- Fainting (syncope) or near fainting
Certain conditions may increase your risk of developing arrhythmia. These include:
- Coronary artery disease, other heart problems and previous heart surgery. Narrowed heart arteries, a heart attack, abnormal heart valves, prior heart surgery, heart failure, cardiomyopathy and other heart damage are risk factors for almost any kind of arrhythmia.
- High blood pressure. This increases your risk of developing coronary artery disease. It may also cause the walls of your left ventricle to become stiff and thick, which can change how electrical impulses travel through your heart.
- Congenital heart disease. Being born with a heart abnormality may affect your heart’s rhythm.
- Thyroid problems. Having an overactive or underactive thyroid gland can raise your risk of arrhythmias.
- Diabetes. Your risk of developing coronary artery disease and high blood pressure greatly increases with uncontrolled diabetes.
- Obstructive sleep apnoea. This disorder, in which your breathing is interrupted during sleep, can increase your risk of bradycardia, atrial fibrillation and other arrhythmias.
- 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.
Other factors that may put you at higher risk of developing an arrhythmia include:
- Drugs and supplements. Certain over-the-counter cough and cold medicines and certain prescription drugs may contribute to arrhythmia development.
- Drinking too much alcohol. Drinking too much alcohol can affect the electrical impulses in your heart and can increase the chance of developing atrial fibrillation.
- Caffeine, nicotine or illegal drug use. Caffeine, nicotine and other stimulants can cause your heart to beat faster and may contribute to the development of more-serious arrhythmias. Illegal 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.
To diagnose a heart arrhythmia, your doctor will review your symptoms and your medical history and conduct a physical examination. Your doctor may ask about or test for conditions that may trigger your arrhythmias, such as heart disease or a problem with your thyroid gland. Your doctor may also perform heart-monitoring tests specific to arrhythmias. These 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 recorder. For sporadic arrhythmias, you keep this portable ECG device available, attaching it to your body and pressing a button when you have symptoms. This lets your doctor check your heart rhythm at the time of your symptoms.
- Echocardiogram. In this non-invasive test, a hand-held device (transducer) placed on your chest uses sound waves to produce images of your heart’s size, structure and motion.
- Implantable loop recorder. If your symptoms are very infrequent, an event recorder may be implanted under your skin in the chest area to continually record your heart’s electrical activity and detect abnormal heart rhythms.
- 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. If doctors are evaluating you to determine if coronary artery disease may be causing the arrhythmia, and you have difficulty exercising, then 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.
- Electrophysiological testing and mapping. In this test, doctors’ thread thin, flexible tubes (catheters) tipped with electrodes 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, what may be causing it and what treatments may help. Your doctor may also use this test to assess the likelihood that you will develop an arrhythmia if you have certain conditions that increase your risk.
To prevent heart arrhythmia, it’s important to live a heart-healthy lifestyle to reduce your risk of heart disease. A heart-healthy lifestyle may include:
- Eating a heart-healthy diet
- Staying physically active and keeping a healthy weight
- Avoiding smoking
- Limiting or avoiding caffeine and alcohol
- Reducing stress, as intense stress and anger can cause heart rhythm problems
- Using over-the-counter medications with caution, as some cold and cough medications contain stimulants that may trigger a rapid heartbeat
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 more serious arrhythmia or arrhythmia complications.
Treating slow heartbeats:
If slow heartbeats (bradycardias) don’t have a cause that can be corrected, doctors often treat them with a pacemaker because there aren’t any medications that can reliably speed up the heart.
A pacemaker is a small 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 rate.
For fast heartbeats (tachycardia’s) 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) by using particular maneuvers that include holding your breath and straining, dunking your face in ice water, or coughing.
These maneuvers affect the nervous system that controls your heartbeat (vagus nerves), often causing your heart rate to slow. However, vagal maneuvers don’t work for all types of arrhythmias.
- Medications. For many types of tachycardia, you may be prescribed medication to control your heart rate or restore a normal heart rhythm. It’s very important to take any anti-arrhythmic medication exactly as directed by your doctor in order to minimize complications.
If you have atrial fibrillation, your doctor may prescribe blood-thinning medications to help keep dangerous blood clots from forming.
- Cardioversion. If you have a certain type of arrhythmia, such as atrial fibrillation, your doctor may use cardioversion, which can be conducted as a procedure or by using medications.
In the procedure, a shock is delivered to your heart through paddles or patches on your chest. The current affects the electrical impulses in your heart and can restore a normal rhythm.
- Catheter ablation. In this procedure, your doctor threads one or more catheters through your blood vessels to your heart. Electrodes at the catheter tips can use heat, extreme cold or radiofrequency energy to damage (ablate) a small spot of heart tissue and create an electrical block along the pathway that’s causing your arrhythmia.
Treatment for heart arrhythmias also may involve the use of an implantable device:
- Pacemaker. A pacemaker is an implantable device that helps control abnormal heart rhythms. A small device is placed under the skin near the collarbone in a minor surgical procedure. An insulated wire extends from the device to the heart, where it’s permanently anchored.
If a pacemaker detects an abnormal heart rate, it emits electrical impulses that stimulate your heart to beat at a normal rate.
- Implantable cardioverter – defibrillator (ICD). Your doctor may recommend this device if you’re at high risk of developing a dangerously fast or irregular heartbeat in the lower half of your heart (ventricular tachycardia or ventricular fibrillation). If you have had sudden cardiac arrest or have certain heart conditions that increase your risk of sudden cardiac arrest, your doctor may also recommend an ICD.
An ICD is a battery-powered unit that’s implanted under the skin near the collarbone similar to a pacemaker. 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 an abnormal heart rhythm, it sends out low- or high-energy shocks to reset the heart to a normal rhythm. An ICD doesn’t prevent an abnormal heart rhythm from occurring, but it treats it if it occurs.
Surgery or other procedures:
In some cases, surgery may be the recommended treatment for heart arrhythmias:
- Maze procedure. In the maze procedure, a surgeon makes a series of surgical incisions in the heart tissue in the upper half of your heart (atria) to create a pattern or maze of scar tissue. Because scar tissue doesn’t conduct electricity, it interferes with stray electrical impulses that cause some types of arrhythmias.
The procedure is effective, but because it requires surgery, it’s usually reserved for people who don’t respond to other treatments or for those who are having heart surgery for other reasons.Coronary bypass surgery. If you have severe coronary artery disease in addition to arrhythmias, your doctor may perform coronary bypass surgery. This procedure may improve the blood flow to your heart.