image by: Rachel's Long QT Foundation
On August 30th, 1997, my seemingly healthy 22 -year-old daughter, Emilie, died suddenly in her sleep from sudden cardiac arrest (SCA). How could a beautiful, healthy young woman just go to bed and die in such a mysterious manner? It’s an understatement to say we were in shock, or grief-stricken. Losing a child was the hardest thing I’ve ever faced.
An autopsy showed only “Acute Cardiac Arrhythmia.” Emilie’s toxicology report was totally negative and the Medical Examiner offered our family no other information about the cause of death.
We had only a few clues. On Emilie’s second day of life she had been observed having a “seizure,” and a nurse told us she appeared somewhat…
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This CredibleMeds Mobile App supports the CredibleMeds.org website which maintains and posts lists of drugs in categories that reflect their ability to prolong the QT interval on the electrocardiogram and/or cause the life-threatening heart arrhythmia, torsades de pointes (TdP).
Shocking news—unless you are a physician or know healthcare—that commonly used antibiotics can cause death!
The authors point out that “nearly one in five patients treated with these antidepressants who underwent electrocardiography had QT intervals which would be considered abnormal” although they stress that the clinical significance of this is unknown.
Working with the UA College of Medicine – Phoenix and Banner University Medical Center – Phoenix and in collaboration with investigators in the Center for Applied Genetics and Genomic Medicine, Dr. Woosley and his team developed a system that calculates each patient’s specific risk of drug-induced long QT syndrome. When the program finds a patient with a high risk of prolonged QT interval, it alerts the prescribing doctor, steering the health-care team toward a different medication or helping to ensure safe use of the medication. The system is helping physicians better manage their patients care.
To diagnose LQTS, we should first know how long a QT interval is too long. Since the QT interval varies with heart rate, we must use the rate-corrected QT (QTc) interval calculated using the Bazett formula (QTc = QT/square root of the R-R interval in seconds). The latest American Heart Association/American College of Cardiology Foundation/Heart Rhythm Society Scientific Statement for interpretation of ECG in 2009 defines prolonged QT as follows: women, QTc lasts for 460 ms or longer men, QTc lasts longer than 450 ms.
My experience with Long QT Syndrome began at about age 7, or at least I think it did. One of the funny things about this condition is you don’t know for sure if it caused you to lose consciousness if you don’t have an EKG or some other kind of heart monitor hooked up to you.
The QT interval is a fluid measurement that is influenced by the physiological and metabolic state of the patient at the time of the ECG. Owing to multiple variables interacting at any given time, patients may have different QT intervals during subsequent ECG examinations. The full extent of personal variability of the QT interval is currently unknown.
Long QT syndrome is believed to be a common cause of unexplained sudden deaths among school athletes, as well as the probable cause of many unexplained drownings.
The SADS Foundation emphasizes that any young person who experiences fainting episodes or seizures should be tested for long QT syndrome. Anyone who suffers an unexplained loss of consciousness should have an electrocardiogram done. So should anyone with a family history of unexplained fainting or sudden death in young people. Because one-third of people with this syndrome have no symptoms, it is not safe to assume that a person without symptoms has not inherited the syndrome. A symptom-free person with long QT syndrome is no less susceptible to sudden death.
Most people with congenital LQTS can be treated effectively with daily beta-blocker medication, which slows the heart rate and diminishes the risk of dangerous heart rhythms. Some people with mild LQTS may only need to take preventive measures.
A variety of ECG findings can be witnessed in LQTS patients. Although the majority of patients have a QTc >440 ms, approximately one-third have a QTc ≤460 ms, and about 10% have normal QTc intervals. Other ECG abnormalities include notched, biphasic, or prolonged T-waves, and the presence of U-waves.
Jackie Todd is 27 years old, with sly eyes, a laugh that seems to come from deep in her belly, and thick, dirty-blond hair that she dyes a fiery copper hue. She also has a small computer inside of her chest. It’s constantly collecting information; it’s a diary of dates, times, and events. In a sense, Jackie’s whole life is archived in a code that she can’t interpret. She jokes that she’s part cyborg, but it’s not entirely a gag: a $50,000 machine is keeping her alive. “This device will do everything it can to prevent my heart from stopping,” she says.
A young woman presented with intermittent shocks from her implantable defibrillator. She was intermittently unconscious and unable to give history. The monitor showed intermittent polymorphic ventricular tachycardia.
Congenital long QT syndrome (LQTS) is one of the most common cardiac channelopathies and is characterized by prolonged ventricular repolarization and life-threatening arrhythmias. The mortality is high among untreated patients.
The congenital long-QT syndrome (LQTS) is a life-threatening cardiac arrhythmia syndrome that represents a leading cause of sudden death in the young. LQTS is typically characterized by a prolongation of the QT interval on the ECG and by the occurrence of syncope or cardiac arrest, mainly precipitated by emotional or physical stress.
Long QT syndrome (LQTS) is an inherited channelopathy which exposes athletes to a risk of sudden cardiac death. Diagnosis is more difficult in this population because: the QT interval is prolonged by training; and the extreme bradycardia frequently observed in athletes makes the QT correction formula less accurate.
At the age of 15, already an elite swimmer, Ms. Vollmer, from Granbury, Tex., was taken to a local doctor after experiencing dizzy spells while training. Doctors discovered she had an abnormal heartbeat and set up a procedure to correct it. But they then discovered she had a genetic cardiac electrical disorder called long QT syndrome, which could lead at any moment to sudden cardiac arrest.
Our understanding of this genetic “channelopathy” has increased dramatically from electro-cardiographic depictions of marked QT interval prolongation and torsades de pointes and clinical descriptions of people experiencing syncope and sudden death to molecular revelations in the 1990s of perturbed ion channel genes.
“Dr. Moss is a pioneer in long QT syndrome and one of the most influential scholars in the fields of electrophysiology and cardiology,”
Emilie saw cardiologists. Her tests were interpreted as normal. The cardiologist’s explanation was that she was tall and thin, and that she was just feeling irregular heartbeats that we all have at times (but which are not clinically significant and which we may not feel).
Unfortunately, we accepted this diagnosis. We now know that she should have seen a pediatric cardiologist, even in 9th grade.
Long QT syndrome is usually diagnosed after a person has a cardiac event (eg, syncope, cardiac arrest). In some situations, this condition is diagnosed after a family member suddenly dies. In some individuals, the diagnosis is made when an electrocardiogram shows QT prolongation.
A history of cardiac events is the most typical clinical presentation in patients with LQTS.
RhythmFirstTM and RhythmNextTM are multi-gene panels for patients with long QT syndrome (LQTS) that can be ordered individually or on a reflex basis.
LQTS may be genetically inherited, but it can also be caused by certain medications you may be taking for other medical conditions.
There are two types of LQTS. In most cases, the condition delays the flow of potassium ions out of heart muscle cells. However, for a small number of people, the sodium channels are affected and too many sodium ions are allowed into the cells.
Safe drug use and the Brugada syndrome
If you have LQTS, your heart’s structure is perfectly normal, but you may have fast, chaotic heartbeats. The fast heartbeats may cause a sudden fainting spell or a seizure. In some cases, the heart can stop and cause sudden death. Long QT is treatable.
LQTS is a disturbance of the heart’s electrical system. It is caused by abnormalities of microscopic pores (proteins) in the heart cells called ion channels.
Nearly half of patients with LQTS NEVER have a symptom!
normal QT = < 440ms (two large squares) – prolonged QT > 450ms produces prolonged ventricular repolarisation -> predisposes to malignant ventricular arrhythmias
You can be born with a genetic mutation that puts you at risk of long QT syndrome. In addition, certain medications and medical conditions might cause long QT syndrome.
Long QT syndrome is treatable.
Long QT syndrome causes problems with the electrical activity of the heart. It's uncommon, occurring in around 1 in every 2,000 people.
Long QT syndrome is often the result of a faulty gene that's inherited from one of your parents. The abnormal gene causes an imbalance in the chemicals that create the electric impulses in your heart.
The syndrome can also be caused by medicines for other conditions.
Beta blockers are medicines that prevent the heart from beating faster in response to physical or emotional stress. Most people who have LQTS are treated with beta blockers.
Doctors may suggest that people who have LQTS 3 take sodium channel blockers, such as mexiletine. These medicines make sodium ion channels less active.
The causes of QT interval prolongation can be divided into congenital or acquired. Congenital causes are usually a result of mutations in ion channels (potassium, calcium, or sodium) with more than 15 identified mutations. In contrast, acquired QT interval prolongation may be a result of electrolyte abnormalities, and/or drugs that affect those ion channels.