LONG QT SYNDROME
Long QT
syndrome is a rare problem with the heart's electrical system. It is
estimated to affect 1 in 5,000 people and result in 3,000 deaths within
the United States each year. As the heart pumps blood, its electrical
system needs to recharge between beats. In people with Long QT syndrome,
the heart's electrical system takes too long to recharge. This makes the
heart susceptible to problematic rhythms, often referred to as arrithymias which can cause the heart to stop pumping blood throughout
the body. If the heart enters into one of these problematic rhythms it
may cause a person to become lightheaded or faint. If the heart does not
return to its normal rhythm, it may lead to death.
Long QT
syndrome is caused by a defect in a set of very small channels (ion
channels) within the heart. These channels allow extremely small,
electrically charged particles (ions) to move in and out of the heart's
cells. The movement of these electrically charged particles is
responsible for both generating and recharging the heart's electrical
signals. In people with Long QT syndrome, as the heart recharges, the
small channels in the heart's cells don't open and close properly to let
the particles move at the correct times. Researchers are still not
certain how these channels are connected to the dangerous heart rhythms
associated with Long QT syndrome, but it is known that the defective
channels make the heart's electrical system unstable as it recharges. When the heart is unstable, it can enter into a problematic heart
rhythm.
Problematic heart rhythms come about when the electrical signals in the
heart become disorganized and cause the heart to pump blood
inefficiently. A few heart rhythms often associated with Long QT
syndrome are Torsades de Pointes, ventricular fibrillation, and
ventricular tachycardia. If the heart falls into any of these three
rhythms death can occur within only a few minutes.
Events
that spark the body to release adrenaline are often cited as events that
may cause people with Long QT syndrome to experience life-threatening
heart rhythms. Terefore, it is usually recommended that people with
Long QT syndrome avoid high intensity physical activities and try to
remain calm during highly emotional events.
Symptoms:
About
half those with long QT syndrome don't have any signs or symptoms.
For
people who do experience signs and symptoms of long QT syndrome, the
most common symptoms include:
Fainting. This is the most common sign of long QT syndrome. In
people with long QT syndrome, fainting spells (syncope) are caused by
the heart temporarily beating in an erratic way. These fainting spells
may happen when you're excited, angry, scared, or during exercise. Fainting in people with long QT syndrome can occur without warning, such
as losing consciousness after being startled by a ringing telephone.
Signs and
symptoms that you're about to faint include lightheadedness, heart
palpitations or irregular heartbeat, weakness and blurred vision. If you
think you're about to faint, sit or lie down and tell someone near you
about your symptoms. However, in long QT syndrome, such warning signs
before fainting are unusual.
Seizures. If the heart continues to beat erratically, the brain
becomes increasingly deprived of oxygen. This can then cause generalized
seizures. In fact, some people with long QT syndrome have been
misdiagnosed as having a seizure disorder and have even been treated
with anti-epileptic medications.
Sudden
death. Normally, the heart returns to its normal rhythm. If this
doesn't happen spontaneously and paramedics don't arrive in time to
convert the rhythm back to normal with an external defibrillator, sudden
death will occur.
Signs and
symptoms of inherited long QT syndrome may start during the first months
of life, or as late as middle age. Most people who experience signs or
symptoms from long QT syndrome have their first episode by the time
they're age 40. Most LQTS-related deaths occur in people ages 11 to 30.
Rarely, signs and symptoms of long QT syndrome may occur during sleep or
arousal from sleep. Some doctors believe that inherited LQTS-causing
mutations likely explain about 10 percent to 15 percent of sudden infant
death syndrome (SIDS).
For
Additional information:
Sudden
Arrithymia Death Syndrome Foundation
www.sads.org
Long QT Syndrome.com
www.long-qt-syndrome.com
