long Q-T syndrome

long Q-T syndrome

A condition that is most common in otherwise healthy young women, which is evoked by physical exercise (in particular swimming) or mental activity (e.g., severe fright or anger, stress), resulting in episodic syncope or, if stimulus is extreme, sudden death related to increased autonomic tone (e.g., while exercising on a hot day) accompanied by sudden onset of ventricular arrhythmia. Once diagnosed, all blood relatives should have an EKG since a prolonged Q-T interval due to delayed repolarisation increases the risk of re-entry phenomenon and malignant ventricular arrhythmia (e.g.,”torsades de points”).

Aetiology
Long Q-T syndrome may be induced by drugs (e.g., antiarrhythmics, phenothiazine, tricyclic antidepressants and lithium), metabolic and electrolyte imbalances, low-energy diets, CNS and autonomic nervous system disease, coronary artery disease, and mitral valve prolapse. Prolonged Q-T interval is also a symptom in Jervell-Lange-Nielsen syndrome, an autosomal recessive [MIM 220400] condition accompanied by deafness and Romano-Ward syndrome, an autosomal-dominant [MIM 192500] condition without deafness.
 
Clinical findings
Syncope, aborted cardiac arrest or sudden death.

Genetics
Often have a strong family history of sudden cardiac death at young age.

EKG
Long Q-T interval, right bundle branch block and elevated ST segment.

Management
Correct hypomagnesaemia and hypopotassaemia (hypokalaemia); beta blockers (propranolol, nadolol); implantable cardioverter-defibrillator; stellectomy.

long Q-T syndrome

Long Q-T interval syndrome Cardiology A clinical complex, most common in otherwise healthy young ♀, evoked by physical–eg, exercise or mental–eg, fright stress, resulting in episodic syncope or, if stimulus is extreme, sudden death related to ↑ autonomic tone–eg, while exercising on a hot day, accompanied by sudden onset of ventricular arrhythmia; once diagnosed, all blood relatives should have an EKG, as a prolonged Q-T interval is associated with ↑ malignant ventricular arrhythmia–eg, 'torsades de points'. See NKX2-5.
References in periodicals archive ?
Heart rhythm abnormalities such as long Q-T syndrome (diagnosed by ECG)
The statement suggests continuous ECG monitoring for at-risk patients, lists the drugs and drug combinations most likely to cause TdP, and provides guidance for managing drug-induced long Q-T syndrome and immediate treatment for TdP.
Medics believe the shock of the bell triggered a rare heart disorder, Long Q-T Syndrome.
Last night, a CRY spokesman said: 'Officially, it is said between four and eight people die of Long Q-T Syndrome a year, but we know that the figure is more than 400.
She concluded Mrs Morgan could have died from Long Q-T Syndrome - an hereditary disorder of the heart's electrical rhythm that can occur in otherwise healthy people.
LONG Q-T SYNDROME: n People with Long Q-T syndrome are susceptible to an abnormally rapid heart rhythm.