QT interval prolongation may be congenital or acquired .


About the congenital Long QT Interval Syndrome (LQTS)

  This genetically determined disease has an incidence of 1:2000 in the general population.

  May result in
ventricular arrhythmias and sudden cardiac death, especially in the young.

  May be autosomal dominant or autosomal recessive.

  The disease is caused by mutations in the genes encoding the
potassium, sodium or calcium channels

      of the cellular membrane (
ion channelopathy).

  At least 12 different types of mutations have been described.

  The efficacy of prophylactic beta blocker therapy is not the same in all types.

 
Romano-Ward Syndrome (RWS): Autosomal dominant form.

      It is the more common type.

 
Jervell Lange-Nielsen Syndrome (JLNS): Autosomal recessive form.

      Sensorineural hearing loss may accompany.

      It is the less common type.

  The subjects do not necessarily have accompanying structural heart disease:

      echocardiography and coronary arteriography may be normal.




Clinical significance

  Prolonged QT interval may result in ventricular arrhythmias (especially Torsades de Pointes) or

      sudden cardiac death.

 
Physical or emotional stress may trigger the onset of ventricular arrhythmias resulting in syncope or

     
sudden cardiac death. These patients are advised to avoid competitive sports.

  These patients have frequent
sudden cardiac death among the history of their family members.

  Ventricular arrhythmias are more commonly observed
in women.

 
Some drugs have been reported to increase the risk of potentially fatal ventricular arrhythmias and

      sudden cardiac death in subjects with LQTS.



References (some with links to free full-text and sample ECGs)

  J Med Case Rep 2017;11(1):88.

  Singapore Med J 2014;55(12):607-611.

  Anatol J Cardiol 2015;15(8):672-4.

  Korean J Intern Med 2011;26(1):99-102.

  J Am Coll Cardiol 2007;49(3):320-328.

  Clin Cardiol 1997;20(3):285-290.

  J Am Coll Cardiol 1993;21(7):1652-1656.

  J Am Coll Cardiol 1984;3(6):1556-61.

  J Am Coll Cardiol 1984;4(2):398-413.

  Ulster Med J 1978;47(2):115-133.





ECG 1a. The limb leads of a patient with long QT syndrome is seen above.

This ECG was donated by Dr. Rainer Schimpf (rainer.schimpf@umm.de) to our website.

Click here for a more detailed ECG




ECG 1b. The precordial leads of the same patient with long QT interval is seen.

This ECG was donated by Dr. Rainer Schimpf (rainer.schimpf@umm.de) to our website.

Click here for a more detailed ECG






ECG 2. LQT1. Long QT Syndrome Type 1.

Dr. Raffaella Bloise and Prof. Silvia Priori have donated this ECG to our website.

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ECG 3. LQT2. Long QT Syndrome Type 2.

Dr. Raffaella Bloise and Prof. Silvia Priori have donated this ECG to our website.

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ECG 4. LQT3. Long QT Syndrome Type 3.

Dr. Carlo Napolitano and Prof. Silvia Priori have donated this ECG to our website.

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ECG 5. Acquired long QT interval in a patient who experienced acute anterior myocardial infarction 1 day ago.

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ECG 6. Long QT interval in a patient with hypothyroidism.

Prof. Dr. Haldun Muderrisoglu has donated this ECG to our website.

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ECG 7. Frequent VPCs in a patient with prolonged QT interval.

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ECG 8a. QT interval prolongation due to SSRI use. Limb leads are seen above.

Dr. Peter Kukla has donated the above ECG to our website.

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ECG 8b. Chest leads of the same patient.

Dr. Peter Kukla has donated the above ECG to our website.

Click here for a more detailed ECG





ECG 9. The above ECG belongs to a patient taking amiodarone. He also has hypokalemia (potassium level 2.9 mmol/L).
The ECG shows QT interval prolongation and macro alternance of the T wave.

Dr. Peter Kukla has donated the above ECG to our website.

Click here for a more detailed ECG





ECG 10. The above ECG belongs to a 11 years-old boy with LQTS. He is receiving Propranolol 20mg three times daily.

Pediatric cardiologist Dr. Mahmut Gokdemir has donated this ECG to our website.

Click here for a more detailed ECG




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