Long QT syndrome factsheet
Introduction
Long QT syndrome (LQTS) is a heart rhythm disorder that can cause abnormally fast or erratic heartbeats, known as arrhythmias.
A QT interval is the time it takes the heart muscle to contract and then recover during a heartbeat. If another electrical impulse arrives during a QT interval that is longer than normal, it can cause arrhythmia.
When arrhythmia happens, less blood is pumped from the heart, which can cause oxygen supply to the brain and body to drop. This can cause fainting or loss of consciousness. LQTS can be life-threatening if not treated quickly.
Signs and symptoms
LQTS is a condition that people are born with, but it is usually only picked up in older children and young adults.
The most common symptoms of LQTS are:
- fast or irregular heartbeats
- fainting or collapsing.
These symptoms, or episodes, can happen when your child is doing activities that increase their heart rate.
This can include:
- exercise like swimming
- emotional situations
- responding to sudden loud noises.
Diagnosis
Diagnosing LQTS can be challenging as many children don't show symptoms early on. A heart specialist or cardiologist can use tests like an electrocardiogram (ECG) to check for abnormal heart rhythms.
Treatment
Treatment focuses on reducing the risk of arrhythmias and includes:
Medications
Beta-blocker medications can help control irregular heartbeats and slow the heart rate.
Lifestyle modifications
Most children will need to avoid activities and sports that put a lot of stress on the body, like swimming. Some children will also need to avoid loud noises and environments where they might be startled or woken up suddenly.
Implantable cardioverter defibrillator
In severe cases, your child may need an implantable cardioverter defibrillator (ICD) inserted.
An ICD is a device that delivers an electrical shock if it senses that the heart is beating in a potentially dangerous rhythm. This shock can help return the heart to normal rhythm and get it pumping again.
Automatic External Defibrillator
An Automatic External Defibrillator (AED) is a portable device that gives an electric shock to get the heart beating normally again. They are programmed to automatically analyse your child’s heartbeat and give an appropriate shock.
AEDs are commonly found in public places like:
- shopping centres
- airports
- workplaces
- parks
- community centres.
Speak to your child’s cardiologist about whether this device is recommended.
Management
Medication to avoid
Some medications can make LQTS worse or increase the risk of fast heart rhythms. Check with your child’s doctor or cardiologist before starting new medications.
Genetic testing
If your child is diagnosed with LQTS, immediate family members, like parents and siblings, should be tested to see if they are also at risk.
Genetic testing is done to see if family members carry a similar or changed gene.
LQTS can affect family members differently. Some family members with LQTS may never have any symptoms, while others might be more severe.
Resources and more information
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The Heart Centre for Children at Westmead
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Supporting Young Hearts
