Long QT Syndrome (LQTS)

---

Description

Long QT syndrome (LQTS) is a heart condition characterized by prolonged electrical activity in the heart, potentially leading to fast, irregular heartbeats (arrhythmias) and, in severe cases, fainting or sudden cardiac arrest. This article will provide a comprehensive overview of LQTS, covering its causes, symptoms, diagnosis, management, and strategies for thriving with the condition.

Genes Involved

LQTS is primarily caused by genetic mutations in genes responsible for regulating the heart‘s electrical activity. Some of the most commonly involved genes include:

• KCNQ1: This gene encodes for a potassium channel protein that helps control the heart‘s rhythm.
• KCNH2: This gene encodes for another potassium channel protein critical for heart function.
• SCN5A: This gene encodes for a sodium channel protein involved in the electrical signals that trigger heart contractions.
• AKAP9: This gene plays a role in anchoring and regulating ion channels in the heart.
• KCNE1: This gene encodes a protein that interacts with the KCNQ1 protein to regulate potassium channels.
• SCN4B: This gene encodes a protein that helps regulate sodium channels in the heart.

Recognizing the Signs and Symptoms

Recognizing the signs and symptoms of LQTS is crucial for prompt diagnosis and treatment. Common symptoms include:

• Fainting or near-fainting (syncope): This is often triggered by physical activity, stress, or emotional excitement.
• Palpitations: A feeling of rapid or irregular heartbeat.
• Dizziness or lightheadedness: This may occur before, during, or after fainting episodes.
• Seizure-like episodes: In some cases, LQTS can cause episodes that resemble seizures.
• Sudden cardiac arrest: This is a life-threatening condition that occurs when the heart suddenly stops beating.

Causes

LQTS can be caused by a variety of factors, including:

• Genetic mutations: As mentioned, mutations in certain genes can lead to LQTS. These mutations are often inherited from a parent, but they can also occur spontaneously.
• Medications: Some medications, such as certain antibiotics and anti-arrhythmics, can prolong the QT interval and increase the risk of LQTS.
• Electrolyte imbalances: Low levels of potassium, magnesium, or calcium in the blood can contribute to LQTS.
• Other medical conditions: Conditions such as hypothyroidism, diabetes, and heart failure can increase the risk of LQTS.
• Environmental factors: Stress, sleep deprivation, and extreme temperatures can also trigger LQTS symptoms in individuals with the condition.

Inheritance/recurrence risk

LQTS is typically an inherited condition, meaning it is passed down through families. The inheritance pattern varies depending on the specific gene involved. The risk of inheriting LQTS depends on the family history and the specific gene mutation. If one parent has LQTS, each child has a 50% chance of inheriting the condition. In some cases, LQTS can occur spontaneously due to new mutations, meaning the condition is not inherited from a parent.