About autosomal dominant long qt syndrome
What is autosomal dominant long qt syndrome?
Romano-Ward syndrome is an inherited heart (cardiac) disorder characterized by abnormalities affecting the electrical system of the heart. The severity of Romano-Ward syndrome varies greatly from case to case. Some individuals may have no apparent symptoms (asymptomatic); others may develop abnormally increased heartbeats (tachyarrhythmias) resulting in episodes of unconsciousness (syncope), cardiac arrest, and potentially sudden death. Romano-Ward syndrome is inherited as an autosomal dominant trait.
What are the symptoms for autosomal dominant long qt syndrome?
Many people who have long QT syndrome don't have any signs or symptoms. You might be aware of your condition only because of:
- Results of an electrocardiogram (ECG) done for an unrelated reason
- A family history of long QT syndrome
- Genetic testing results
Fainting is the most common sign of long QT syndrome.
Fainting (syncope) occurs when the heart temporarily beats in an unorganized way. You might faint when you're excited, angry or scared or during exercise. Things that startle you — for example, a telephone or an alarm clock — can cause you to lose consciousness. A Fainting spell from long QT syndrome can occur with little to no warning. Some people have a warning sign first, such as Lightheadedness, heart Palpitations, Weakness or Blurred vision.
Seizures also may occur in some people with LQTS.
Generally, the heart returns to its normal rhythm. If this doesn't happen by itself, or if an external defibrillator isn't used in time to set your heartbeat back to normal, sudden death will occur.
Most people with symptoms of long QT syndrome have their first episode by age 40. However, congenital long QT syndrome signs and symptoms can occur in babies during the first weeks to months after birth, or in childhood or later. Some people with congenital long QT syndrome never have signs or symptoms.
Signs and symptoms of long QT syndrome might occur during sleep.
What are the causes for autosomal dominant long qt syndrome?
Causes of congenital long QT syndrome
More than 17 genes have been linked to long QT syndrome so far, and researchers have identified hundreds of mutations within these genes.
Doctors have described two forms of congenital long QT syndrome:
- Romano-Ward syndrome (autosomal dominant form). This more common form occurs in people who inherit only a single gene variant from one parent.
- Jervell and Lange-Nielsen syndrome (autosomal recessive form). This rare form usually occurs earlier and is more severe. In this syndrome, children receive the faulty gene variants from both parents. The children are born with long QT syndrome and deafness.
Causes of acquired long QT syndrome
More than 100 medications — many of them common — can lengthen the QT interval in otherwise healthy people and cause acquired long QT syndrome.
Medications that can cause acquired long QT syndrome include:
- Certain common antibiotics, such as erythromycin (Eryc, Erythrocin, others), azithromycin (Zithromax, Zmax) and others
- Certain antifungal medications taken by mouth used to treat yeast infections
- Diuretics that cause an electrolyte imbalance (low potassium, most commonly)
- Heart rhythm drugs (especially anti-arrhythmic medications that lengthen the QT interval)
- Certain antidepressant and antipsychotic medications
- Some anti-nausea medications
If your condition is caused by a medication, it may be called drug-induced long QT syndrome. Always tell your doctor about all the medications you take, including those you buy without a prescription.
Other causes of acquired long QT syndrome include:
- Low potassium level (hypokalemia)
- Low calcium level (hypocalcemia)
- Low magnesium level (hypomagnesemia)
- COVID-19 infection
What are the treatments for autosomal dominant long qt syndrome?
Treatment is aimed at preventing symptoms such as syncope or cardiac arrest. Specific medications, avoidance of triggering events and QT prolonging medication, and certain medical devices may all be used to treat individuals with Long QT syndrome. Genetic counseling is of great benefit for affected individuals and their families to understand implications for family members, recurrence risk, family planning options, and psychological adjustment to disease and/or carrier status.
The treatment of choice for most affected individuals is drug therapy with beta-adrenergic blocking agents (beta blockers). Beta blockers prevent adrenergic stimulation of the heart via the beta-receptors and can be highly effective in treating long QT syndrome. Nadolol and propranolol are longer acting beta-blockers and the agents of choice in managing the condition. Even though many patients now diagnosed are asymptomatic due to better awareness of the condition and more effective family cascade testing (i.e. identifying family members who are at risk of also having long QT syndrome), beta-blockers are still recommended if any evidence of the condition can be elicited either at rest or with provocation such as exercise stress tests. Beta blockers need to be taken daily and the failure to do so (noncompliance) by affected individuals can lead to the development of symptoms including sudden death.
Individuals for whom beta blockers are unsuccessful or contraindicated may be treated by a surgical procedure in which the autonomic nerves supplying the heart are interrupted (left cardiac sympathetic denervation or sympathectomy). The autonomic nerves release catecholamines which stimulate the heart via the beta-receptors, so this can be considered another form of anti-adrenergic therapy. The heart rhythm is controlled by the sympathetic nervous system, which controls many of the involuntary actions of the body. These nerves work to regulate the heart rhythm and this procedure can significantly reduce the frequency of arrhythmic events. During the procedure, a small cut (incision) is made in the chest wall and specific autonomic nerves supplying the heart are cut. Left cardiac sympathetic denervation is usually reserved for individuals who are considered high risk, develop symptoms despite beta blocker therapy, or are contraindicated to or cannot tolerate beta blocker therapy.
For affected individuals who have been resuscitated from cardiac arrest (whether on or off beta blockers), treatment with an implantable automatic cardioverter-defibrillator or ICD should be considered. These small devices are implanted under the skin of the chest, and wires are passed down into the heart to monitor the heart rhythm on a beat by beat basis. The device detects episodes of torsades de pointes automatically and delivers an electrical shock to restore normal cardiac rhythm. ICDs are also considered for individuals who experience recurrent syncopal events despite therapy with beta blockers. ICDs do not prevent the occurrence of torsade de pointes and, therefore, are used in conjunction with beta blockers and/or cardiac sympathectomy. An ICD is a therapy that carries significant medical and psychological complications, especially in younger individuals, and should be undertaken only after detailed consultation with appropriate medical personnel experienced in the management of LQTS and a careful consideration of the risks and benefits. Specific therapeutic procedures and interventions may vary, depending upon numerous factors, such as specific subtype; effectiveness of medications; an individual’s previous history, age and general health; and/or other elements. Decisions concerning the use of particular drug regimens and/or other treatments should be made by physicians and other members of the healthcare team in careful consultation with the patient based upon the specifics of his or her case; a thorough discussion of the potential benefits and risks, including possible side effects and long-term effects; patient preference; and other appropriate factors.
Some individuals with long QT syndrome are encouraged to avoid potential triggering events such as jumping into cold water or amusement park rides. Individuals with Long QT syndrome who wish to participate in competitive sports should be referred to a clinical expert for evaluation of risk. Affected individuals need to avoid drugs that prolong the QT interval, a full list of such drugs can be found at www.crediblemeds.org.
What are the risk factors for autosomal dominant long qt syndrome?
The following things may increase your risk of developing congenital or acquired long QT syndrome or its symptoms:
- A history of cardiac arrest
- Having a first-degree relative (parent, sibling) with long QT syndrome
- Using medications known to cause prolonged QT intervals
- Being female and on heart medication
- Excessive vomiting or diarrhea
- Eating disorders, such as anorexia nervosa, which cause electrolyte imbalances
Sexual intercourse doesn't appear to be high risk for patients with long QT syndrome. Pregnancy and delivery aren't associated with an increased risk of symptoms in women diagnosed with long QT syndrome. However, if you have the condition and are pregnant, your doctor will want to carefully monitor you during and after pregnancy.
Is there a cure/medications for autosomal dominant long qt syndrome?
Autosomal dominant long QT syndrome is caused by abnormalities of the heart’s electrical conduction system. LQTS occurs if there is any defect in the ion channels, causing a delay in the time it takes for the electrical system to recharge after each heartbeat.
- Treatment is aimed at preventing symptoms such as syncope or cardiac arrest.
- For most individuals affected by Autosomal dominant long QT syndrome, the treatment of choice is drug therapy with beta-adrenergic blocking agents (beta-blockers). Beta-blockers prevent adrenergic stimulation of the heart via the beta-receptors and can be highly effective in treating long QT syndrome.
- If in case beat blockers are unsuccessful, surgical procedures where the autonomic nerves supplying the heart are interrupted.
- There are also specific therapeutic procedures and interventions that vary, depending on factors such as specific subtype, the effectiveness of medications, an individual’s previous history, age, and general health; and/or other elements.
- Other medications may be used to shorten the Q-T interval.
- Decisions regarding the use of particular drugs and/or other treatments for Autosomal dominant long QT syndrome should be made by physicians and other members of the healthcare team.
List of symptoms
Palpitations,Presyncope and syncope,Exertion,Excitement,Stress
List of conditions
Hypokalemia,Certain neurologic conditions including subarachnoid bleed,Structural heart disease
List of Drugs
Beta-adrenergic blocking agents (beta blockers)