Arrhythmia is an irregular heartbeat. It may be too fast, too slow, or out of rhythm. It occurs when the electrical signals that control the heartbeat are delayed or blocked. This may occur because the specialized cells that produce the signal are not working properly. It might also occur if the signal does not travel through the heart normally. This could be the result of scar tissue or an alteration in the structure of the heart. An arrhythmia can also occur if some other part of the heart starts to produce electrical signals.
A properly functioning heart has clear pathways along which uninterrupted electrical impulses travel from the sinus node to the ventricles. If there is a disruption along the pathways or a problem with the tissues that create the impulses, the heart may not beat correctly. This can cause an arrhythmia.
Conditions that may block the pathways, interrupt electrical impulses, or otherwise cause a heart not to function properly include:
- heart disease
- heart failure
- high blood pressure (hypertension)
- an overactive or underactive thyroid gland
- rheumatic heart disease
- scarring of the heart muscle, for example from a heart attack
An arrhythmia can develop if the heart’s physiology has been changed. The change may be caused by reduced blood supply or damage to heart tissue. If the heart does not receive an adequate supply of blood, its cells and tissues may be starved of oxygen and unable to properly conduct electrical impulses. If a heart’s tissues have been damaged or destroyed, the electrical impulses may not be able to travel properly. Conditions that may change the heart’s structure include:
Coronary Artery Disease (CAD)
CAD is a condition in which the arteries in the heart become narrow. This often leads to a heart attack. In a heart attack, part of the heart muscle dies due to lack of oxygen. This causes scarring, which can interfere with the movement of electrical impulses through the heart. This may cause the heart to beat too fast (tachycardia), too slow (bradycardia) or erratically (fibrillation).
Cardiomyopathy is disease of the heart muscle. This may cause expansion or stretching of the walls of the ventricles. It may thicken and constrict the wall of the left ventricle. This affects the way blood is pumped through the heart and may damage heart tissue.
Valvular Heart Diseases
The heart valves can become narrow and/or leak. This may cause sections of the heart muscle to stretch and thicken in some parts and thin in other ones.
In some cases, such as Wolff-Parkinson-White syndrome or Brugada syndrome, the cause of an arrhythmia is a congenital heart defect or a genetic defect—meaning it is present from birth. In other cases, a cause may not be found.
Many factors increase the risk of arrhythmia. Some you can control; others you cannot. Eliminating as many of these factors as you can through lifestyle and dietary changes will improve your chances of living a long healthy life.
The risk of arrhythmia increases with age. This can be due to many factors including structural heart disease, drug use, and heart attack. In addition, there are normal changes that occur as the heart ages. These may decrease the conductivity of electrical impulses.
Consuming large amounts of alcohol can affect the electrical impulses in your heart in a variety of ways. Multiple studies demonstrate that moderate to heavy alcohol consumption significantly increases the risk of developing atrial fibrillation. Chronic alcohol abuse may lead to cardiomyopathy that causes your heart to beat less effectively.
Nicotine or Caffeine
Caffeine, nicotine, and other stimulants accelerate your heart rate. Long-term, frequent use of these stimulants—particularly nicotine—may lead to more serious arrhythmias or heart diseases that can cause arrhythmias.
A person with uncontrolled diabetes is at an increased risk of developing coronary artery disease and high blood pressure. Uncontrolled diabetes also increases the chances of heart attack compared to a person whose diabetes is controlled.
Some over-the-counter and prescription medicines—such as cough suppressants and cold medications—contain pseudoephedrine. This may speed up your heart rate, increase blood pressure, and enhance an arrhythmia. Some cardiac medications, including those used to treat arrhythmia, can paradoxically cause an arrhythmia.
Some herbs have been associated with arrhythmias. These include creatine, guarana, cola nut, and ephedra.
Electrolytes, such as potassium, sodium, calcium, and magnesium, are essential for maintaining proper conduction of electricity between cells. Electrolyte levels that are either too high or too low can affect electrical impulses and may result in an arrhythmia.
Congenital heart defects—problems that are present at birth—can affect the heart’s structure and its ability to function properly.
High Blood Pressure
High blood pressure (hypertension) increases your risk of developing coronary artery disease or experiencing heart failure. It may also cause the walls of your heart to become thicker, which can change how electrical impulses circulate in your heart.
Amphetamines and cocaine profoundly affect the heart, possibly causing any number of arrhythmias. They might also cause ventricular fibrillation, which can lead to sudden death.
Endocarditis or pericarditis—which can be caused by viral infections—can weaken the heart muscle and the sac around the heart. This makes transmission of electrical impulses and contractions more difficult.
Obesity is a risk factor for coronary heart disease, diabetes, cancer, cardiovascular disease, heart disease, and arrhythmia.
Obstructive Sleep Apnea
People with obstructive sleep apnea often experience bradycardia or atrial fibrillation. Sleep apnea can also deprive your body of oxygen, which places even more stress on the heart.
Previous Heart Surgery
Heart surgery may damage heart muscle, making electrical conduction and contraction more difficult.
An overactive or underactive thyroid increases your chances of developing an arrhythmia. Whether it is releasing too many hormones or not enough, your thyroid gland can affect your heartbeat, which may lead to a too-fast or too-slow heart rate.