Long QT syndrome

The long QT syndrome is a rare hereditary disease? caused by genes that are transmitted to people by their parents - that causes changes in the conduction of electrical impulses in the heart.
The electrical activity of heart cells is controlled by a set of channels pumping ions such as sodium and potassium, into and out of cells. If a person inherits genes that cause changes in these channels, it can affect the action of cardiac cells.
Typically, an electrical impulse is initiated in the sinus node, situated in the upper chamber of the right heart (right atrium). This electrical impulse is transmitted subsequently to the lower chambers of the heart, called ventricles, leading to contraction of their muscle cells. This contraction causes blood to exit the heart through the aorta and toward the rest of the body.
Then, cardiac muscle cells relax. During the relaxation phase, the electric loads need to recover the cells.
There are normal durations for each phase of the heartbeat, called intervals. An examination as the electrocardiogram (ECG) can show how long it takes the pulse to pass through certain sections of the heart and how long it takes the heart muscle cells of the ventricles recover. The recovery time is known as "QT".
The QT interval lasts only a fraction of a second, normally taking about one third of the full heartbeat. In people with long QT syndrome, the interval lasts longer than normal, since the heart muscle cells are having trouble getting ready for the next contraction.
A prolonged QT interval does not cause symptoms. However, the delay in charging affect the electrical rhythm of the heart. This makes the heart more prone to develop abnormal heart rhythms, called arrhythmias. These arrhythmias can be dangerous or even fatal.
People with long QT syndrome may not always present an abnormally long QT interval on an ECG done at rest. Many different factors can influence the recovery time, even normal heart cells. Sometimes long QT intervals occur only during exercise, at times of intense emotion or after the individual has scared
The hereditary long QT syndrome is not as common as a prolonged QT interval as a result of a drug or an imbalance of certain minerals in the bloodstream. There are known more than 50 drugs that are capable of prolonging the QT interval and heart disrupt the rap.
The two syndromes hereditary long QT are better understood syndrome Romano-Ward syndrome and Jervell and Lange-Nielsen. Of the two, Romano-Ward syndrome is the most common. It is an autosomal dominant hereditary disease? which means that a person can have a long QT if inherit an abnormal gene from either parent. The syndrome of Jervell and Lange-Nielsen is rare. People with this syndrome may have a very long QT interval and are also deaf. The syndrome of Jervell and Lange-Nielsen is an autosomal recessive hereditary disease? which means that a person needs to inherit two abnormal genes, one from each parent, to present this syndrome.
Treatment
Treatment of individuals with an inherited long QT syndrome, generally, do not shorten the duration of the QT interval, but can greatly reduce the risk of potentially fatal abnormal heart rhythms and episodes of unconsciousness. Most people with a hereditary long QT syndrome taking beta-blockers, which prevent the heart to beat faster during exercise or stress-causing events.
If symptoms occur when a person engages in physical exercise or in a situation of stress, it is preferable to avoid the practice of strenuous exercise and keep stress under control. The breathing exercises, medication and yoga are activities that can help manage stress. The physician may also suggest food intake with a high content of potassium, such as bananas or ingestion of potassium supplements.
If a person has had a loss of consciousness or have developed dangerous heart rhythms due to long QT syndrome, presents a higher risk of serious complications of this syndrome. The doctor may advise the patient to perform a minor surgical procedure to implant a pacemaker or cardioverter-defibrillator. These devices monitor the heart rate and applies electrical currents to the heart when they detect the presence of an abnormal heart rhythm.
Another option consists in the surgical patient undergoing a procedure during which nerves are severed leading the heart to beat faster in response to physical or emotional stress. After surgery, the patient has much less likely to develop abnormal heart rhythms in response to stress or exercise.

Prevention
There is no way to prevent hereditary long QT syndrome. However, people with hereditary long QT syndrome should avoid taking medicines that can make Qt even longer than it is naturally. Food intake in sufficient quantity and the maintenance of a balanced diet can prevent dihydro-electrolyte imbalances that may increase the duration of the QT interval.
Anyone who starts a new medication should speak with the pharmacist or your doctor about potential interactions with current medication. This includes people who have no history of long QT intervals. Some drug combinations can significantly prolong the QT interval, which may increase the risk of an arrhythmia.