long QT syndrome 12

What is Long QT Syndrome?

Long QT syndrome (LQTS) is a type of conduction disorder that affects the heart's electrical system, causing it to take longer than normal to recharge between heartbeats [1]. This can lead to potentially life-threatening arrhythmias, such as torsades de pointes [3].

Causes and Symptoms

Long QT syndrome is usually caused by a faulty gene inherited from parents, which affects the body's electrical system [9]. People with LQTS may experience fast, erratic heartbeats when exercising or experiencing emotional excitement, leading to symptoms like fainting or seizures [6]. In some cases, this can lead to sudden cardiac death [8].

Characteristics

The condition is characterized by a prolongation of the QT interval on electrocardiograms (ECGs) and a risk of syncope or cardiac arrest [5][7]. The symptoms of LQTS are due to the ventricular tachyarrhythmia torsade de pointes (TdP), which can be life-threatening if not treated promptly [8].

References

• [1] Long QT syndrome is a type of conduction disorder. A conduction disorder is a problem with the electrical system that controls your heartbeats.
• [3] Long QT syndrome (LQTS) is an abnormal feature of the heart's electrical system that can lead to a potentially life-threatening arrhythmia called torsades de pointes.
• [5] LQTS is typically characterized by a prolongation of the QT interval on the ECG and by the occurrence of syncope or cardiac arrest, mainly ...
• [6] A person with long QT syndrome may experience fast, erratic heartbeats when exercising, or at times of emotional excitement. This may cause fainting, seizures ...
• [7] Long QT syndrome (LQTS) is a congenital disorder characterized by a prolongation of the QT interval on electrocardiograms (ECGs) and a ...
• [8] The symptoms of LQTS are syncope and sudden cardiac death. These events are due to the ventricular tachyarrhythmia torsade de pointes (TdP), Figure 3. Most ...
• [9] LQTS is usually caused by a faulty gene inherited from your parents. Genes decide how the body works and what parts of you are like, such as eye colour or hair ...

Symptoms of Long QT Syndrome

Long QT syndrome can cause unusual heart rhythms, which may not always be accompanied by symptoms. However, when symptoms do occur, they can be quite distressing.

• Fainting: One of the most common symptoms of long QT syndrome is fainting, especially in response to acute emotions such as anger or surprise, exercise, menstruation, or swimming in cold water [12].
• Abnormal heart rhythms: Long QT syndrome can cause irregular electrical activity in the heart, leading to abnormal heart rhythms [11].
• Palpitations: Some people with long QT syndrome may experience fast, erratic heartbeats when exercising or experiencing emotional excitement [9].

It's essential to note that not everyone with long QT syndrome will exhibit symptoms. In some cases, the condition may only be detected through an electrocardiogram (ECG) for another reason.

References: [12] Long QT Syndrome is a condition that can cause unusual heart rhythms. ... While LQTS doesn’t always cause symptoms, ... If you experiencing fainting or other signs of an abnormal heart rhythm, ... [9] A person with long QT syndrome may experience fast, erratic heartbeats when exercising, or at times of emotional excitement. This may cause fainting, seizures ... [11] Long QT syndrome type 1: Potassium ion channels (receptors in the heart) do not properly work, which causes irregular electrical heart activity. Torsades de pointes, a potentially fatal heart arrhythmia, is more common in this subtype, but the arrhythmia is more likely to stop without treatment, making it less fatal.Long QT syndrome type 1 is most commonly triggered by exercise.

Diagnostic Tests for Long QT Syndrome

Long QT syndrome (LQTS) can be diagnosed through a combination of clinical criteria and electrocardiogram (ECG) testing. Sometimes, additional tests such as exercise and/or provocative testing may be required to confirm the diagnosis.

• Clinical Criteria: The diagnosis of LQTS is based on a set of clinical criteria that take into account the patient's medical history, family history, symptoms, and physical examination.
• Electrocardiogram (ECG): An ECG is the most common test used to diagnose LQTS. It records the electrical activity of the heart and can show abnormalities in the QT interval, which is a key feature of LQTS.
• Exercise and/or Provocative Testing: In some cases, additional testing may be required to confirm the diagnosis of LQTS. This can include exercise tests or provocative tests that stimulate the heart to beat faster.

Treatment

Once diagnosed, treatment for LQTS typically involves avoiding triggers that can cause abnormal heart rhythms, taking beta-blockers to slow down the heart rate, and in some cases, implanting an implantable cardioverter-defibrillator (ICD) to prevent life-threatening arrhythmias.

Treatment Options for Long QT Syndrome

Long QT syndrome (LQTS) can be treated with various medications to manage the condition and prevent life-threatening complications.

• Beta blockers: These are the most commonly prescribed medications for LQTS. They work by slowing down the heart rate and reducing the risk of abnormal heartbeats.
• Magnesium therapy: In some cases, magnesium may be administered through a needle in a vein to help regulate the heartbeat.
• Other pharmacologic therapies: Depending on the individual case, other medications such as potassium, spironolactone, mexiletine, and left cardiac sympathetic denervation (LCSD) may be considered.

Medications that can cause LQTS

Certain medications can trigger acquired long QT syndrome, including:

• Some antibiotics like erythromycin and azithromycin
• Antidepressants such as amitriptyline
• Other classes of therapeutic agents

It's essential to note that treatment for people with inherited long QT syndrome generally doesn't shorten the length of the QT interval but can greatly reduce the risk of life-threatening abnormal heartbeats and fainting spells.

References

[12] Long QT syndrome (LQTS) is characterized by inherited or acquired prolonged QT interval on the surface electrocardiogram. ... Transvenous pacing was the appropriate treatment until the QT c normalized . ... The example of drug-induced long QT syndrome. Drug Saf. 2001;24(8):575–585. doi: 10.2165/00002018-200124080-00002. [Google Scholar] 10

[14] If a medicine causes acquired long QT syndrome, the disorder may be called drug-induced long QT syndrome. More than 100 medicines can cause prolonged QT intervals in otherwise healthy people. Medicines that can cause LQTS include: Some antibiotics, such as erythromycin (Eryc, Erythrocin, others), azithromycin (Zithromax) and others.

[15] Treatment for people with inherited long QT syndrome generally doesn't shorten the length of the QT interval. But it can greatly reduce the risk of life-threatening abnormal heartbeats and fainting spells. Most people with inherited long QT syndrome take beta blockers, which prevent the heart from beating fast during exercise or stressful events.

Differential Diagnosis of Long QT Syndrome

Long QT syndrome (LQTS) is a congenital disorder characterized by a prolongation of the QT interval on electrocardiograms (ECGs) and a propensity to ventricular tachyarrhythmias, which may lead to syncope, cardiac arrest, or sudden death. The differential diagnosis for LQTS includes various conditions that can mimic its symptoms.

Conditions to Consider

• Brugada Syndrome: A genetic disorder that affects the heart's electrical system, leading to abnormal ECG readings and an increased risk of sudden cardiac death.
• Short QT Syndrome: A rare condition characterized by a shortened QT interval on ECGs, which can increase the risk of arrhythmias and sudden cardiac death.
• Epilepsy: A neurological disorder that can cause seizures, some of which may be mistaken for LQTS symptoms.
• Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT): A rare genetic disorder that affects the heart's electrical system, leading to abnormal heart rhythms and an increased risk of sudden cardiac death.

Prenatal Diagnosis

In some cases, prenatal diagnosis may be considered when one or both parents have a history of LQTS. This can help identify potential carriers and allow for early intervention if necessary.

References

• [12] Long QT Syndrome/QT prolongation; Brugada Syndrome · Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)