Definition
Long QT syndrome is a disorder of the hearth rhythm. It causes very rapid heartbeats. These fast heartbeats can lead to fainting or seizures, or sometimes, when the heart beats erratically for a long period of time it can result in unexpected death.
A person can be born with genetic mutation that increases the risk of long QT syndrome. Also, some medical conditions and medicine can cause the long QT syndrome to occur.
The long QT syndrome can be treated by avoiding medications known to affect the heartbeat, taking medications that prevent rapid heartbeat, and limiting physical activity. Some cases of LQTS will have to be treated with surgery or medical device implantation.
Symptoms
Most of the long QT syndrome cases are discovered because of a genetic testing or ECG, as this syndrome usually doesn’t have any symptoms. However, when there are symptoms, they most common one is fainting. The fainting spells occur due to the erratic beating of the heart. They can occur when a person is excited, scared, angry or during exercising. A person that is about to faint may experience irregular heartbeat, weakness, lightheadedness and blurred vision. Anyway, people with long QT syndrome usually faint or lose consciousness unexpectedly without any warning. If the heartbeat isn’t temporarily, but continues to beat erratically for longer period of time, the brain will become deprived of oxygen what causes seizures. Generally, the heart reaffirms the normal beat rhythm, but if it doesn’t, spontaneously or with the help of external defibrillator, sudden, unexpected and quick death can happen.
The symptoms of long QT syndrome can appear at any age, early in life or during middle age, but usually the first episode of long QT syndrome happens by the age of 40.
There are rare cases of long QT syndrome symptoms that appeared during sleep or arousal from sleep.
If a person suddenly faints after excitement, while exercising or usa of new medications, it is advisable to see a doctor.
A person can also be tested for a long QT syndrome if there is a history of this syndrome in the family.
Causes
The long QT syndrome means that the heart muscles needs more time than normally to recharge between the beats. This disorder can be noticed on a ECG and it is called prolonged Q-T interval. The Q-T interval on the ECG shows how much time the heart needs to begin the next contraction. Measurement of this interval can tell whether the contractions happen in a normal period of time or it takes longer than normally.
The long QT syndrome can be a result of abnormalities in the heart’s electrical recharging system. The abnormalities can be inherited or can happen due to some underlying medical condition or certain medication.
Twelve genes that are associated with long QT syndrome and hundreds of mutations of these genes have been discovered until now. Almost 75% of the long QT syndrome cases occurred as a result of mutation in three genes. Two forms of inherited long QT syndrome exist: Romano-Ward syndrome and Jervell and Lang-Nielsen syndrome. The Romano-Ward type is more common, with less severe symptoms, and occurs in people that inherited one genetic variant from one parent. Jervell and Lange-Nielsen type occurs early in children (especially babies) that have inherited genetic variants from both parents. The symptoms of this type are usually severe.
The cause of long QT syndrome can also be a result of certain medications. There are around 50 medications that are known to prolong the Q-T interval in healthy people thus developing acquired QT syndrome also known as drug-induced long QT syndrome. Medications that are known to prolong the Q-T interval are: antibiotics, antidepressants, diuretics, heart medications, diabetes medicines, drugs that lower the cholesterol and some antifungal drugs.
Risk factors
The risk of long QT syndrome is higher for:
- Children, teenagers and young adults that have been fainting without any explicable reason, have experienced near drownings, accidents or seizures as well as their family members
- Close relatives of people with long QT syndrome
- People that are taking pills that are known to prolong the Q-T intervals
- People with anorexia nervosa
Complications
Sometimes, problems may never appear. However, the prolonged Q-T intervals can cause irregular heart rhythms i.e. arrhythmias that can lead to life-threatening situations. The arrhythmias that can happen are: twist of the points and ventricular fibrillation.
Treatment
The treatment for long QT syndrome can be with medications, medical devices, surgery or change of the lifestyle.
- Medications that can be used are: beta blockers, mexiletine, potassium and fish oil
- Medical devices and surgeries that are recommended are: a pacemaker or implantable cardioverter-defibrillator or left cardiac sympathetic denervation surgery
- Lifestyle changes that a person with long QT syndrome should make are: to avoid strenuous exercising or contact sports, to reduce very loud noise, to stay away from stressful situations or situations that can make a person excited or angry
Prevention
A person that has been diagnosed with long QT syndrome should carefully select medicine, avoid amphetamines, cocaine, or any kind of street drugs, seek medical help for conditions that cause diarrhea or too much vomiting as they could result in low blood-potassium levels and provoke an long QT syndrome episode in people at risk.
