Sudden Arrhythmic Death Syndrome
Dr. Simon Modi – Consultant Cardiologist/Electrophysiologist, Dr. Robert Cooper –
Cardiology Specialist Registrar, Suzanne Kelly – Heart Rhythm Specialist Nurse
Liverpool Heart and Chest Hospital
Long QT syndrome:
Long QT syndrome is a purely electrical disorder of the heart. It does not show up on heart
scans as the heart size and structure is normal. An ECG is the only way this abnormality can
be can be picked up. Sometimes ECG monitoring for 24 hours, or during periods of exercise
or adrenaline surges are required to diagnose the condition. Under certain circumstances it
can cause a fatal disturbance of the heart’s rhythm. Exercise, swimming, startling noises,
emotion, certain medication, body mineral upsets (e.g. blood potassium levels) and (in
women) the period after childbirth are all known triggers for rhythm disturbance in the long
QT syndrome. Most long QT syndrome is inherited and screening for a family history of
‘events’ is important. People with long QT syndrome generally feel well but may have noted
prior dizzy spells or faints on exertion.
ECG showing the long QT syndrome
Left = normal ECG and QT interval (distance between arrows). Right = Long QT syndrome