(See also Overview of Abnormal Heart Rhythms Overview of Abnormal Heart Rhythms Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more 
.)
A channelopathy is a defect in one or more of the microscopic channels in the walls of heart cells through which electrolytes Overview of Electrolytes More than half of a person's body weight is water. Doctors think about water in the body as being restricted to various spaces, called fluid compartments. The three main compartments are Fluid... read more such as sodium, potassium, and calcium enter and leave the cells. It is this flow of electrolytes that is responsible for the normal electrical activity Normal electrical pathway Abnormal heart rhythms (arrhythmias) are sequences of heartbeats that are irregular, too fast, too slow, or conducted via an abnormal electrical pathway through the heart. Heart disorders are... read more of the heart. There are several different types of channel, and a defect in one of them can interfere with the heart's ability to maintain a steady rhythm. The heart may suddenly go too fast or too slow or even stop completely (cardiac arrest Cardiac Arrest and CPR Cardiac arrest is when the heart stops pumping blood and oxygen to the brain and other organs and tissues. Sometimes a person can be revived after cardiac arrest, particularly if treatment is... read more 
).
Channelopathies are usually caused by a disorder in which there is a mutation in one of the genes that determine the make up of heart cell channels. However, some people develop a channelopathy as a complication of certain autoimmune or inflammatory disorders, such as systemic lupus erythematosus Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic autoimmune inflammatory connective tissue disorder that can involve joints, kidneys, skin, mucous membranes, and blood vessel walls. Problems in the... read more 
or Sjogren syndrome Sjögren Syndrome Sjögren syndrome is a common autoimmune connective tissue disorder and is characterized by excessive dryness of the eyes, mouth, and other mucous membranes. White blood cells can infiltrate... read more 
.
Most people who have cardiac channelopathies have no other heart disease, such as a heart attack Acute Coronary Syndromes (Heart Attack; Myocardial Infarction; Unstable Angina) Acute coronary syndromes result from a sudden blockage in a coronary artery. This blockage causes unstable angina or a heart attack (myocardial infarction), depending on the location and amount... read more 
or a heart valve disorder Overview of Heart Valve Disorders Heart valves regulate the flow of blood through the heart's four chambers—two small, round upper chambers (atria) and two larger, cone-shaped lower chambers (ventricles). Each ventricle has... read more 
.
The most common channelopathies cause
Other, more rare cardiac channelopathies include the following:
Short QT syndrome
Early repolarization syndrome
Catecholaminergic polymorphic ventricular tachycardia (CPVT)
Brugada syndrome
Isolated progressive cardiac conduction disease
The electrical defects in the channelopathies sometimes cause ventricular tachycardia Ventricular Tachycardia Ventricular tachycardia is a heart rhythm that originates in the ventricles (lower chambers of the heart) and produces a heart rate of at least 120 beats per minute (the normal heart rate is... read more 
, a dangerously rapid heart rhythm, or ventricular fibrillation Ventricular Fibrillation Ventricular fibrillation is a potentially fatal, uncoordinated series of very rapid, ineffective contractions of the ventricles (lower chambers of the heart) caused by many chaotic electrical... read more 
, in which the heart does not beat at all. Channelopathies are more common than doctors previously thought and may be the cause of about 10% of sudden cardiac deaths.
Symptoms of Cardiac Channelopathies
Some people never have any symptoms, but many people have fainting because of ventricular tachycardia. Those who have ventricular fibrillation have sudden cardiac arrest Cardiac Arrest and CPR Cardiac arrest is when the heart stops pumping blood and oxygen to the brain and other organs and tissues. Sometimes a person can be revived after cardiac arrest, particularly if treatment is... read more .
Symptoms may be triggered by fever, exercise, or some drugs, including some drugs used to treat abnormal heart rhythms and some antidepressants.
Diagnosis of Cardiac Channelopathies
Electrocardiography
Doctors consider a channelopathy when people or their family members have a history of fainting or cardiac arrest without an obvious cause (such as a known heart problem), especially if the cardiac arrest occurred at a young age.
If doctors suspect a channelopathy, they do electrocardiography Electrocardiography Electrocardiography (ECG) is a quick, simple, painless procedure in which the heart’s electrical impulses are amplified and recorded. This record, the electrocardiogram (also known as an ECG)... read more 
(ECG), continuous ambulatory heart monitoring Continuous Ambulatory Electrocardiography A standard electrocardiograph (ECG) records the heart's electrical activity for only a few seconds. This can detect abnormalities that are constant; however, sometimes abnormal heart rhythms... read more , and usually cardiac stress testing Stress Testing Stressing the heart (by exercise or by use of stimulant drugs to make the heart beat faster and more forcibly) can help identify coronary artery disease. In coronary artery disease, blood flow... read more 
. Genetic testing is sometimes done. If a channelopathy is confirmed, people should have regular follow up with ECG and ambulatory heart monitoring to look for asymptomatic heart rhythm disturbances. .
Because channelopathies are usually a genetic disorder, family members of people with a channelopathy are at risk. Close family members should be evaluated by a doctor, including with ECG and ambulatory heart monitoring.
Treatment of Cardiac Channelopathies
Implantable cardioverter-defibrillator
Usually, an implantable cardioverter-defibrillator Implantable Cardioverter-Defibrillator (ICD) There are many causes of abnormal heart rhythms (arrhythmias). Some arrhythmias are harmless and do not need treatment. Sometimes arrhythmias stop on their own or with changes in lifestyle,... read more (ICD), a small device that can detect a dangerously abnormal heart rhythm and deliver a shock to correct it, is used. This procedure is similar to implantation of an artificial pacemaker Artificial Pacemakers There are many causes of abnormal heart rhythms (arrhythmias). Some arrhythmias are harmless and do not need treatment. Sometimes arrhythmias stop on their own or with changes in lifestyle,... read more 
. People should avoid things that might trigger an abnormal heart rhythm.
More Information
The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
American Heart Association: Arrhythmia: Information to help people understand their risks of arrhythmias as well as information on diagnosis and treatment
