| Long
QT Syndrome (LQTS)
Click here to learn
about:
What
is LQTS?
- LQTS is a
disorder of the heart’s electrical system.
- The electrical
activity of the heart is produced by the flow of ions (electrically
charged particles of sodium, calcium, potassium, and chloride) in and
out of the cells of the heart. Tiny ion channels control this flow.
-
 |
| Normal
QT interval |
 |
| Long
QT interval |
The QT interval
is the section on the electrocardiogram
(ECG) that represents the time it takes for the electrical system
to fire an impulse through the ventricles and then recharge. It is translated
to the time it takes for the heart muscle to contract and then recover.
- LQTS is a
defect in the ion channels, causing a delay in the time it takes for
the electrical system to recharge after each heartbeat. When the QT
interval is longer than normal, it increases the risk for torsade de
pointes, a life-threatening form of ventricular tachycardia.
- LQTS is rare.
The prevalence is about 1 in 5,000 persons in the Untied States.
What
causes LQTS?
Long QT syndrome can
be aquired or congenital:
Acquired LQTS
is caused by many medications. Sensitivity to these medications may be
related to genetic causes. See medications to avoid.
Congenital
LQTS is usually inherited. It is caused by
an abnormality in the gene that forms the ion channels, slowing the recovery
phase of the heartbeat. Forms of inherited LQTS include:
- Recent
Classifications – LQT1, LQT2, LQT3, LQT4, LQT5; these are classified
by the type of channel which causes the LQTS. The type of LQTS classification
is related to the risk of future cardiac events, those with LQT3 having
the highest risk of life-threatening arrhythmias.
- Jervell,
Lange-Nielsen Syndrome – both parents are carriers of the abnormal
gene, but they do not have LQTS. Each child has a 25-percent chance
of inheriting LQTS. This syndrome is associated with deafness at birth
and is extremely rare, as there is a small chance that both parents
would carry the LQTS gene.
- Romano-Ward
Syndrome – one parent has LQTS and the other parent does not. Each
child has a 50-percent chance of inheriting the abnormal gene. In this
syndrome, hearing is normal; however the likelihood that children in
this family would have LQTS is greater. The gene may be present in all
the couple’s children, some of them or none at all.
Those at risk for
LQTS include:
- children
who are deaf at birth
- children
and young adults who have unexplained sudden death or syncope in family
members
- blood relatives
of family members with LQTS
- those taking
certain medications known to increase the risk for LQTS. See medications
to avoid
What
are the symptoms?
The most common symptoms
include:
- syncope
- seizures
- sudden death
The symptoms of LQTS
are related to torsade de pointes. During this arrhythmia, the ventricle
beats very fast and irregularly. The heart is unable to pump blood effectively
to the body. If the brain does not receive an adequate blood supply, syncope
(fainting) and seizure-like activity will occur. If the arrhythmia continues,
sudden death will occur. If the heart rhythm returns to normal, symptoms
will stop.
Symptoms are most
common during:
- exercise
(or within a few minutes after)
- emotional
excitement, especially being startled
- during sleep
or upon waking suddenly
Some people with congenital
LQTS never have symptoms. The diagnosis is made during a routine ECG or
during an evaluation because a family member has it. Symptoms usually
first appear during the early teen years.
How
is LQTS diagnosed?
LQTS is usually diagnosed
by measuring the QT interval on the ECG. Other testing may
include:
Your doctor will also
ask you if you have a:
- family history
of LQTS
- family history
of unexplained fainting, seizures, or cardiac arrest
- history of
fainting, seizures or cardiac arrest, especially with exercise
How
is it treated?
Treatment is aimed
at preventing sudden death and controlling symptoms. Treatment includes:
Medications
Most patients (even
those without symptoms) are treated with a beta-blocker. Other
medications may be used to shorten the QT interval. Your doctor will discuss
what medications are best for you. Check the drug
search
to find out more about your medications. It
is important to know:
- the names
of your medications
- what they
are for
- how often
and at what times to take them
Medications
to avoid
There are many medications
that can prolong the QT interval. Those with LQTS may be more prone to
the effects of these medications. If you have LQTS, you should:
- Avoid all over-the-counter
medications (except for plain aspirin or acetaminophen)
- Tell all your health
care professionals you have LQTS, and there are many drugs you cannot
take
- Talk
to your doctor before taking any medications prescribed for any other
medical condition. The following types of medications may affect you
if you have LQTS:
- antihistamines
- antidepressants,
mental illness medications
- heart
medications
- antibiotics,
antifungals, antivirals
- intestinal
medications
- anticonvulsants
- diuretics
- antihypertensives
- migraine
medications
- cholesterol
lowering medications
| For a complete,
updated list of medications, contact the SADS Foundation at www.sads.org* |
Devices
- Patients who have
a history of cardiac arrest or symptoms, in spite of beta-blocker therapy,
may receive an implantable
cardioverter defibrillator (ICD). This device detects life-threatening
arrhythmias and automatically shocks the heart to prevent sudden death.
- Patients who have
an abnormally slow heart rate may receive a pacemaker.
Lifestyle
changes
- Family
testing
All
first-line relatives (brothers, sisters, parents and children) should
have EKG testing. Any other family members who have a history of seizures
or fainting should also undergo testing.
- Exercise
If
you have LQTS, sometimes, fatal arrhythmias occur with exercise. So,
ask your cardiologist if you are able to exercise. Competitive sports
are NOT recommended.
- Buddy
system
Your
family and friends should be told you have LQTS. They should be told
to call for emergency help (911) if you begin to have symptoms or faint.
Future
treatments will be geared toward more gene specific therapies. For
example, certain types of LQTS are more likely to initiate events during
exercise, while others are more related to startling or emotional distress.
Your doctor will be able to give you activity guidelines based on the
specific type of LQTS gene you carry. Therapies may be directed to treat
the specific gene, rather than prevention of future complications.
How to find a doctor
if you have Long QT Syndrome (LQTS)
Adult
LQTS: Click
here to find a Cleveland Clinic Heart Center Cardiologist who treats Abnormal
Heart Rhythms
Pediatrics: Dr.
Richard Sterba
Resources:
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© Copyright 2002- 2006 The Cleveland Clinic Foundation. All
rights reserved, reviewed 10/06 |
