Arrhythmogenic Right Ventricular Dysplasia (ARVD)
ARVD is a genetic heart condition in which the muscle of the right ventricle is replaced by fat and fibrosis, which causes abnormal heart rhythms. ARVD is estimated to affect one in 5,000 people. The disease can affect both men and women. Although it is a relatively uncommon cause of sudden cardiac death, it accounts for up to one fifth of sudden cardiac death in people under 35 years of age.
Atrial Septal Defect (ASD)
ASD is a congenital heart defect in which the wall that separates the upper heart chambers (atria) does not close completely. Congenital means the defect is present at birth.
In fetal circulation, there is normally an opening between the two atria (the upper chambers of the heart) to allow blood to bypass the lungs. This opening usually closes around the time the baby is born.
If the ASD is persistent, blood continues to flow from the left to the right atria. This is called a shunt. If too much blood moves to the right side of the heart, pressures in the lungs build up. The shunt can be reversed so that blood flows from right to left. Many problems can occur if the shunt is large, but small atrial septal defects often cause very few problems and may be found much later in life.
ASD is not very common. When the person has no other congenital defect, symptoms may be absent, particularly in children. Symptoms may begin any time after birth through childhood.
Atrial fibrillation/flutter is a heart rhythm disorder (arrhythmia). It usually involves a rapid heart rate, in which the upper heart chambers (atria) are stimulated to contract in a very disorganized and abnormal manner.
Arrhythmias are caused by a disruption of the normal electrical conduction system of the heart.
In atrial fibrillation, the atria are stimulated to contract very quickly and differently from the normal pattern. The impulses are sent to the ventricles in an irregular pattern. Some impulses fail to be transmitted. This makes the ventricles beat abnormally, leading to an irregular (and usually fast) pulse.
Atrial fibrillation can affect both men and women. It becomes more common with increasing age.
Brugada Syndrome is a condition that causes a disruption of the heart’s normal rhythm. Specifically, this disorder can lead to uncoordinated electrical activity in the heart’s lower chambers (ventricles), an abnormality called ventricular arrhythmia. If untreated, the irregular heartbeats can cause fainting (syncope), seizures, difficulty breathing, or sudden death. These complications typically occur when an affected person is resting or asleep. Brugada syndrome usually becomes apparent in adulthood, although signs and symptoms, including sudden death, can occur any time from early infancy to old age.
Electrocardiogram (ECG) (EKG)
An electrocardiogram is a simple, painless, non-invasive test that records the heart’s electrical activity.
Long QT Syndrome
Long QT Syndrome is an infrequent, hereditary disorder of the heart’s electrical rhythm that can occur in otherwise healthy people. It usually affects children or young adults.
When the heart contracts, it emits an electrical signal. This signal can be recorded on an electrocardiogram (ECG) and produces a characteristic waveform. The different parts of this waveform are designated by letters — P, Q, R, S and T. The Q-T interval represents the time for electrical activation and inactivation of the ventricles, the lower chambers of the heart. A doctor can measure the time it takes for the Q-T interval to occur (in fractions of a second), and can tell if it occurs in a normal amount of time. If it takes longer than normal, it’s called a prolonged Q-T interval.
Hypertrophic Cardiomyopathy (HCM)
HCM is a condition in which the heart muscle becomes thick. The thickening makes it harder for blood to leave the heart, forcing the heart to work harder to pump blood.
Hypertrophic cardiomyopathy is often asymmetrical, meaning one part of the heart is thicker than the other parts. The condition is usually passed down through families (inherited). It is believed to be a result of several problems (defects) with the genes that control heart muscle growth.
Younger people are likely to have a more severe form of hypertrophic cardiomopathy. However, the condition is seen in people of all ages.
Wolff-Parkinson White Syndrome (WPW)
WPW is a heart condition in which there is an extra electrical pathway (circuit) in the heart. The condition can lead to episodes of rapid heart rate (tachycardia).
Wolff-Parkinson-White is one of the most common causes of fast heart rate disorders in infants and children.
Normally, electrical signals in the heart go through a pathway that helps the heart beat regularly. The wiring of the heart prevents extra beats from occurring and keeps the next beat from happening too soon.
In people with Wolff-Parkinson-White syndrome, there is an extra, or accessory, pathway that may cause a very rapid heart rate. This is called supraventricular tachycardia.
Sources: American Heart Association, MedlinePlus, Johns Hopkins