- Diseases, Disorders & Conditions
Heart Condition – Long QT Syndrome
Long QT Syndrome (LQTS)
The long QT syndrome is a serious heart condition that is usually acquired through a genetic mutation; therefore, twins are particularly vulnerable. It also occurs to closely related family members. There are also cases of this disease occurring due to certain medications and medical conditions. This is a rare disorder and experts believe approximately one in 7000 people have LQTS, but they also know it goes undiagnosed quite often. In addition, this disorder causes about 3000 to 4000 sudden deaths in children and young adults annually.
The first abnormal heart rhythm usually occurs by the time an individual is 12 years old and 90% occur by the time the individual is 40 years old. It is rarely diagnosed after 40. It often goes undiagnosed.
This disorder is more common in women than men, and boys often return to normal after puberty. Women are more likely to faint or die suddenly from this disorder during menstruation and shortly after giving birth. Children who are born deaf are also at increased risk.
Heart Normal Electrical Rhythm
What is Long QT Syndrome?
Long QT syndrome is a disorder of the heart’s electrical system. The heart may suddenly have an uncontrollable, dangerous arrhythmia, which is usually in response to stress or vigorous exercise. The heart arrhythmia will be a problem if the heart rate or the normal rhythm changes into a potentially lethal one
The Normal Heart Rhythm
The ECG measures the electrical impulses as five distinct waves, using P, Q, R, S and T. While the P initiates the heart rate, the space between the start of the Q wave to the end of the T wave equals the time it takes for the heart to contract and refill with blood before the next contraction. Doctors measure the Q–T interval to find out if it occurs in a normal amount of time. The upper time limit of the QT interval accounts for age, sex, regularity and speed of the heart rate.
At this 12 genes associated with LQTS have been discovered so far, but hundreds of mutations within these genes have been identified also. These mutations account for approximately 70 to 75 percent of LQTS cases. Obviously there is much research to be done to fully understand this disorder.
Unfortunately, my nephew’s finance, who is a twin, has recently been diagnosed with this genetic disease and is currently being evaluated. In her case, she has had no symptoms, but her sister has had fainting spells and is being actively treated as they both wait for DNA results.
If you have the genetic version of LQTS, you will have this disorder throughout your life. Not everyone has symptoms, while others are very symptomatic or experience sudden death. There are seven types of this inherited disorder. DNA studies always accompany this diagnosis as it may be inherited from one parent or from both. Obviously if you’ve inherited from both parents the probability of symptoms is greater.
The most common inherited LQTS are called one, two and three. In LQTS 1 exercise, particularly swimming, and emotional stress can trigger arrhythmias. In LQTS2 the extreme emotions, such as a sudden surprise, can also trigger arrhythmias. In LQTS 3 a slow heart rate can trigger arrhythmias, which occurs during sleep.
Normal versus Ventricular Rhythm
Medication-Induced and Diseases
There are more than 15 medicines that have been found to cause this disorder. Some of the most common medicines include:
- Decongestants and antihistamines
- Antidepressants and antipsychotic medications
- Cholesterol-lowering medications
- Some diabetes medications
Other causes of this syndrome include; severe vomiting or diarrhea due to the major loss of sodium or potassium in ions from the bloodstream. The disorder will only last until these ion levels normal. Anorexia nervosa, bulimia and some thyroid disorders can also cause a drop in potassium ion levels in the blood.
Lethal Ventricular Rhythm
Heart Problem Symptoms
Many people with LQTS do not have symptoms of heart problems, but for those that do the most common is fainting spells, which can occur when you’re very excited, angry, scared or exercising. Some signs that you’re about to faint include lightheadedness, heart palpitations, irregular heartbeat, weakness and blurred vision, however, warning signs are unusual for these patients.
If the heart rhythm remains erratic the brain becomes deprived of oxygen, so seizures are a symptom. If the heart rhythm does not return to normal and there is no medical intervention accessible, than sudden-death will occur.
What is Long QT Syndrome?
Patients diagnosed with this disorder will have to make lifestyle changes so they can avoid anything that may trigger an abnormal heart rhythm. Medications that link them the QT interval or lower the potassium blood level are forbidden. Patients are asked to add or potassium to their diets by eating foods, such as bananas or taking a potassium supplement.
As my niece goes through the diagnostic phase, she is only allowed to take ibuprofen for pain, and there is only one antibiotic that will be allowed if necessary. She has to change her lifestyle completely as she was a runner. She can;t ride on roller coasters or get overly stressed. Her sister has had an implanted heart monitor, so the doctor can be informed if her heart rate becomes to irregular or beats too fast.
Treatment of LQTS
The treatment will depend on the type of LQTS symptoms for each patient. Most medications are limited for these patients as many tend to lengthen the QT interval.
There are some specific medications to avoid once the type of LQTS is verified, such as for patients who have LQTS3. They are usually prescribed a sodium channel blocker medicine, but this is not used for any other types of this disorder. Beta blocker medications are sometimes used to prevent cardiac events for some patients also.
If the doctor finds the patient is at risk for more complications, they will use more aggressive treatments. This might include an implanted device, such as a pacemaker or a cardioverter defibrillator as they control abnormal heart rhythms. Sometimes surgeries are done on the nerves that regulate the heartbeat.
This is obviously a rather frightening disease for anyone as you may have no symptoms at all, then suddenly go into a lethal rhythm and die. As research progresses we certainly hope that patients can be diagnosed prior to having any symptoms, and new treatments will also be developed.
© 2014 Pamela Oglesby