Short QT syndrome

What is short QT syndrome?

Short QT syndrome is a condition that causes a disruption of the heart's normal rhythm (arrhythmia). In people with this condition, the heart (cardiac) muscle takes less time than usual to recharge between beats. If untreated, the irregular heartbeats can lead to a spectrum of signs and symptoms, from dizziness and fainting (syncope) to cardiac arrest and sudden death.

The signs and symptoms of short QT syndrome, including sudden death, can occur any time from early infancy to old age. This condition may explain some cases of sudden infant death syndrome (SIDS), which is a major cause of unexplained death in babies younger than one year. Other people with short QT syndrome never experience any health problems associated with the condition.

How common is short QT syndrome?

Fewer than 30 cases of short QT syndrome have been identified since this condition was discovered in 2000.

What genes are related to short QT syndrome?

Mutations in the KCNH2, KCNJ2, and KCNQ1 genes cause short QT syndrome.

The KCNH2, KCNJ2, and KCNQ1 genes provide instructions for making proteins that act as channels across the cell membrane. These channels transport positively charged atoms (ions) of potassium into and out of cells. In cardiac muscle, these ion channels play critical roles in maintaining the heart's normal rhythm. Mutations in the KCNH2, KCNJ2, or KCNQ1 gene increase the activity of the channels, which changes the flow of potassium ions between cells. This disruption in ion transport alters the way the heart beats, leading to the abnormal heart rhythm characteristic of short QT syndrome.

How do people inherit short QT syndrome?

Short QT syndrome appears to have an autosomal dominant pattern of inheritance, which means one copy of the altered gene in each cell is sufficient to cause the disorder. Some affected individuals have a family history of heart problems and sudden cardiac death. Other cases are classified as sporadic and occur in people with no apparent history of short QT syndrome in their family.

Short QT Syndrome on Wikipedia

'''Short QT syndrome''' is a genetic disease of the electrical system of the heart. It is made up of a constellation of signs and symptoms, made up of a short QT interval interval on EKG (≤ 300 millisecond ) that doesn't significantly change with heart rate, tall and peaked T waves, and a structurally normal heart. Short QT syndrome appears to be inherited in an autosomal dominant pattern, and a few affected families have been identified.

Symptoms and signs

Individuals with short QT syndrome frequently complain of palpitations and may have syncope (loss of consciousness) that is unexplained. Due to the autosomal dominant inheritance pattern, most individuals will have family members with a history of unexplained or sudden death at a young age (even in infancy), palpitations, or atrial fibrillation. Short QT syndrome is associated with an increased risk of sudden cardiac death, most likely due to ventricular fibrillation.

Diagnosis

The diagnosis of short QT syndrome is made up of characteristic history and findings on EKG and electrophysiologic testing. There are currently no set guidelines for the diagnosis of short QT syndrome.

Electrocardiogam

The characteristic findings of short QT syndrome on EKG are a short QT interval, typically ≤ 300 millisecond , that doesn't significantly change with the heart rate. Tall, peaked T waves may also be noted. Individuals may also have an underlying atrium (anatomy) rhythm of atrial fibrillation.

Electrophysiologic Studies

In the electrophysiology lab, individuals with short QT syndrome are noted to have short refractory periods, both in the atrium (anatomy) as well as in the Ventricle (heart). Also, ventricular fibrillation is frequently induced on programmed stimulation.

Etiology

The etiology of short QT syndrome is unclear at this time. A current hypothesis is that ... [ Read More ]

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