Case Report

A heart stopping performance

BMJ 2012; 345 doi: http://dx.doi.org/10.1136/bmj.e6076 (Published 20 September 2012)
Cite this as: BMJ 2012;345:e6076

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  1. Joyee Basu, foundation year 2 trainee1,
  2. Timothy Betts, consultant cardiologist 2
  1. 1Stoke Mandeville Hospital, Aylesbury HP21 8AL, UK
  2. 2John Radcliffe Hospital, Oxford, UK
  1. Correspondence to: J Basu joyeebasu11{at}yahoo.co.uk

After a show jumping round at a local horse show, a 23 year old woman who had been competing slumped and fell from her horse. An onsite paramedic immediately administered basic life support. An ambulance crew arrived shortly afterwards and performed electrocardiography (ECG), which showed ventricular fibrillation. A single shock was administered before the return of spontaneous circulation.

On arrival at the intensive care unit, she was intubated and ventilated. She was cooled for 24 hours and given inotropic support. On clinical examination she was unresponsive, tachycardic, and hypotensive. There were no other positive findings on clinical examination. Blood results (including calcium, magnesium, potassium, and troponin measurements), toxicology screen, septic screen, and computed tomography of the head were negative. She was taking no regular drugs and had no history of cardiac problems or a family history of cardiac arrest or sudden death. ECG performed before cooling and on discharge from intensive care confirmed the diagnosis of long QT syndrome. An echocardiogram showed a structurally normal heart. She later had a dual chamber implantable cardioverter defibrillator fitted and was treated with an oral β blocker.

Questions

  • 1 What is the definition of a long QT interval?

  • 2 What are the common causes of long QT syndrome?

  • 3 Which clinical criteria are used to diagnose long QT syndrome?

  • 4 What is the risk of sudden cardiac death with long QT syndrome?

  • 5 What is the treatment strategy for long QT syndrome?

  • 6 What advice would you give a patient with newly diagnosed long QT syndrome?

Answers

1 What is the definition of a long QT interval?

Short answer

When corrected for rate, a QT interval of greater than 450 ms in males and greater than 460 ms in females is considered abnormal.1 The average corrected QT interval in patients with genetically confirmed long QT syndrome is 490 ms. The QT interval is best measured in …

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