Long-QT syndrome is the name given to a heart condition that can be life-threatening. It involves an abnormally prolonged QT interval.
What is long-QT syndrome?
Long-QT syndrome is a life-threatening disease of the heart that is rare. It can be both hereditary and acquired during life. People whose hearts are otherwise healthy can suffer sudden cardiac death from long-QT syndrome. There are different congenital long-QT syndromes, which include Jervell and Lange Nielsen syndrome (JLNS) and Romano-Ward syndrome, most of which are inherited in an autosomal dominant manner. The term long-QT syndrome refers to a prolongation of the QT time on an ECG (electrocardiogram). In this case, the frequency-corrected QT time is more than 440 milliseconds. A typical feature of the heart disease is palpitations, which occur in fits and starts. Torsade de pointes tachycardia, which is considered life-threatening, is not uncommon. The cardiac arrhythmias threaten dizziness, abrupt loss of consciousness and ventricular fibrillation with cardiac arrest. In many cases, however, affected individuals do not suffer symptoms.
Causes
Long-QT syndrome is triggered by minor abnormalities in the electrical transmission of signals in the heart muscle cells. Delayed repolarization of the action potential occurs, affecting the plateau phase, which is also called phase 2. Due to abnormal properties of ion channels, prolongation of the plateau phase occurs in congenital (congenital) long-QT syndrome. In this case, ion transport of the potassium ion channel either decreases or there is increased transport of the sodium ion channel. The action potential forms an important basis for the excitation of the heart muscle cells. It is regulated by the interaction of ionic currents. Phase 0 of the action potential is considered to be the depolarization of the cardiac muscle cells, which occurs due to the influx of calcium and sodium ions. Repolarization is initiated by phase 1, which involves the outflow of potassium from the cell. Phase 1 is followed by phase 2 or the plateau phase, during which the prolonged influx of calcium ions occurs. The release of additional calcium ions from the sarcoplasmic reticulum is triggered by these ions. It takes approximately 100 milliseconds for the calcium channels to close again, for the calcium to exit the cell or return to storage, and for the slackening of the myocardium to begin. This is followed by phase 3, in which the membrane potential returns to its initial position. There it remains in a resting state until the next excitation occurs. Congenital long-QT syndrome is caused by an ion channel dysfunction that is mutation-related and results in a structural change of an ion channel. In addition to the congenital form, which results from a gene mutation, there are also acquired forms of the heart disease. They can be caused by inflammation of the heart muscle (myocarditis), circulatory disorders, electrolyte imbalances or the use of various drugs. The drugs responsible include primarily class I, II, and III antiarrhythmic drugs, psychotropic drugs, and various antibiotics that have an inhibitory effect on repolarization and cause drug-induced long-QT syndrome.
Symptoms, complaints, and signs
If symptoms occur as a result of long-QT syndrome, they are abrupt-onset torsades de pointes tachycardias. Ventricular tachycardia is noticeable by sweating, general malaise, chest tightness, and cardiac restlessness. In addition, circulatory collapse (syncope) may set in. Collapse and tachycardia occur predominantly in stressful situations or during physical exertion. If ventricular tachycardia is not treated medically, there is a risk of ventricular fibrillation, which results in permanent cardiac arrest and ends with the patient’s death.
Diagnosis and course of the disease
If long-QT syndrome is suspected, the treating physician performs a resting ECG. Occasionally, an exercise ECG may also be useful. If the QT interval lengthens during the resting ECG, this is considered a landmark indication of the syndrome. The frequency-corrected QT time (QTC) is 450 milliseconds in men, while it is 470 milliseconds in women.Because long-QT syndrome is usually inherited, family history is considered very important for diagnosis. In addition, molecular genetic mutation detection within the leukocyte DNA is possible. For this purpose, PCR amplification and sequencing of known risk genes are performed. Two to five milliliters of EDTA blood are used for the sample material. The course of the long-QT syndrome depends on whether symptoms occur or not. Thus, the prognosis is considered negative if symptoms appear and no treatment is given. However, in principle, it is possible to help most patients with appropriate therapy.
Complications
Long-QT syndrome is a very dangerous disease that, in the worst case, can lead to the death of the patient. For this reason, long-QT syndrome definitely requires treatment by a physician. As a rule, those affected suffer from heavy sweating and also a feeling of malaise. This significantly limits and reduces the quality of life. In the further course, the affected person can also suffer a circulatory collapse and lose consciousness. Loss of consciousness not infrequently also leads to injuries that can occur in the event of a fall. Especially in stressful situations, the long-QT syndrome leads to significant impairments. The resilience of the affected person is considerably reduced and fatigue and exhaustion occur. Strong stress can also lead to cardiac arrest and thus to death in the patient. As a rule, the symptoms of long-QT syndrome can be limited and treated with the help of medication. In general, no particular complications occur. In acute emergencies, however, the use of a defibrillator is necessary to revive the affected person. Life expectancy is limited and reduced by long-QT syndrome.
When should you see a doctor?
If seizures or signs of arrhythmia occur, it is best to call 911. Symptoms of this type indicate a serious condition and, in the worst case, can lead to the patient’s death. If the affected person loses consciousness, the emergency physician must be called. In parallel, relatives should provide first aid and ensure that the affected person can breathe and has a pulse. Less serious symptoms that require clarification are shortness of breath, rapid exhaustion, and audible palpitations. Chest pain should also be clarified quickly by a medical professional. Patients at risk include people who regularly take medication or suffer from low serum potassium blood levels. A slow heart rhythm can also cause long-QT syndrome. Those who belong to the risk groups should pay close attention to any warning signs and, if in doubt, make an appointment with a doctor. The appropriate physician is the cardiologist. The individual symptom picture is treated by the family doctor and various specialists and specialists (such as neurologists or physiotherapists).
Treatment and therapy
The standard treatment of congenital long-QT syndrome is the administration of beta-receptor blockers. These are able to significantly reduce the severe arrhythmias. However, if syncope continues to occur, implantation of an implantable cardiac defibrillator (ICD) is advisable. Implantation should also take place after a survived cardiac arrest. If the long-QT syndrome is caused by taking certain medications, the triggering agent should be discontinued immediately. In contrast to the congenital form, the administration of beta-blockers is not advisable because of the risk of bradycardia, which in turn increases the risk of life-threatening cardiac arrhythmias. Magnesium supplementation, on the other hand, is considered a proven remedy. Physical stress is considered problematic in long-QT syndrome. This is especially true in the case of sudden onset or termination of stress, as well as in the case of pressure fluctuations and cold.
Outlook and prognosis
If left untreated, long-QT syndrome leads to circulatory collapse, loss of consciousness, and premature death in most cases. Because it is a life-threatening health development, acute action is required. Intensive medical care is necessary to prevent permanent damage and to ensure the survival of the affected person.Consultation with a physician should be sought already at the first irregularities in cardiac activity. If the diagnosis is made at an early stage, the further course of the disease is significantly improved and the probability of survival is increased. The affected person requires the implantation of a defibrillator. This will ensure sufficient cardiac activity in the long term and can regulate restrictions in cardiac activity. Although the surgical intervention is associated with risks, it is nevertheless a routine procedure. If no further complications occur, the patient can continue to live. However, the mental as well as physical strain must be adapted to the possibilities of the organism and must be reduced. In many cases, the restructuring of everyday life is necessary so that no disturbances occur and risk factors are minimized. In the long term, the affected person must undergo regular check-ups with a doctor so that irregularities can be detected and corrected at an early stage. This can lead to emotional states of stress. In addition, medication must be administered from the time the defibrillator is used. These are fraught with side effects.
Prevention
To prevent cardiac arrhythmias caused by long-QT syndrome, the practice of sports such as diving, swimming, surfing, tennis, weightlifting, and bodybuilding should be avoided. In contrast, moderate physical activities such as skating, walking, or jogging are considered reasonable.
Aftercare
Because self-healing cannot occur in long-QT syndrome, aftercare focuses primarily on relieving existing symptoms. Affected individuals suffer from severe pain in the heart and continue to experience persistent fatigue and lassitude. As a result, in most cases they are dependent on help from their social environment. Since the burden on all involved is sometimes very high, this can lead to depression and other psychological upsets. It is therefore advisable to seek professional, psychological help to make it easier to cope with the disease. A gentle mode in everyday life with many rest phases can help to compensate for the permanently existing, inner restlessness and possibly occurring sleep complaints. Since the further course of the disease strongly depends on the time of diagnosis, no general prediction can be made. In addition, the exchange with other sufferers of the long-QT syndrome can intercept the own helplessness and promote a more self-confident handling of the situation.
Here’s what you can do yourself
As a rule, the options for self-help in long-QT syndrome are severely limited. This is especially the case if the syndrome is not triggered by certain medications but is due to heart disease. However, if long-QT syndrome is triggered by taking medications, they must be discontinued immediately or replaced with other medications. Changing and discontinuing medications should always be done after consulting a physician. Furthermore, the symptoms of long-QT syndrome can be reduced by taking beta-blockers. In this case, the patient should ensure that he or she takes the medication regularly. Increased magnesium intake can also have a positive effect on the course of the disease and alleviate the symptoms. Magnesium can be taken either through supplements or through various foods, such as nuts or fish. Due to the long-QT syndrome, the affected person should continue to refrain from heavy physical exertion. This also includes refraining from strenuous sports. Above all, exertion should not start suddenly, as this places unnecessary strain on the heart. Likewise, the affected person should not spend too long in the cold and avoid pressure fluctuations, which can occur, for example, when flying or diving.
