Cardiac Channelopathies
(See also Overview of Abnormal Heart Rhythms.)
Most people who have cardiac channelopathies have no other heart disease, such as a heart attack or a heart valve disorder, 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:
The electrical defects sometimes cause ventricular tachycardia, a dangerously rapid heart rhythm, or ventricular fibrillation, in which the heart does not beat at all.
Symptoms
Some people never have any symptoms, but many people have fainting because of ventricular tachycardia. Those who have ventricular fibrillation have sudden cardiac arrest.
Symptoms may be triggered by fever or some drugs, including some drugs used to treat abnormal heart rhythms and some antidepressants.
Diagnosis
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 (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
Usually, an implantable cardioverter-defibrillator (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.
