(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 
.)
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 
, but they carry mutations in the genes that determine the make-up or the regulation of heart membrane pores (channels) and are predisposed to heart rhythm abnormalities.
The most common channelopathies cause
Other, more rare cardiac channelopathies include the following:
Short QT syndrome
J-wave syndrome
Catecholaminergic polymorphic ventricular tachycardia (CPVT)
Brugada syndrome
The electrical defects 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.
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 or some drugs, including some drugs used to treat abnormal heart rhythms and some antidepressants.
Diagnosis of Cardiac Channelopathies
Electrocardiography
Doctors consider a channelopathy in people who have family members who have a history of fainting or unexplained death due to a heart problem, especially if the death occurred at a young age.
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) is used to make the diagnosis. But sometimes the pattern of ECG abnormalities is less clear. In such cases, doctors may try to provoke the heart rhythm disturbance with a drug or with exercise, enabling doctors to make a diagnosis.
Treatment of Cardiac Channelopathies
Implantable cardioverter-defibrillator
Usually, an implantable cardioverter-defibrillator Restoring normal rhythm (ICD), a small device that can detect an abnormal heart rhythm and deliver a shock to correct it, is used. This procedure is similar to implantation of an artificial pacemaker.
More Information
The following is an English-language resource that 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
