Amuse-Bouche at today’s morning report was prolonged QT interval on the ECG. This conditions is associated with an increased risk of torsades de pointes, which is a life threatening polymorphic ventricular tachycardia.
Long QT can be genetic or acquired. Drugs are a common cause of prolonged QT. Among them are:
• Antiarrhythmic drugs such as sotolol, amiodarone, quinidine, procainamide
• Macrolide and floquinolone antibiotics
• Certain psychotropic medications like TCAs, haloperidol, methadone
Drug-induced prolonged QT is an idiosyncratic event, but there are some identified risk factors.
• Rapid IV infusion of the drug
• Electrolyte abnormalities (hypokalemia, hypocalcemia or hypomagnesemia)
• Use of other drugs known to prolong the QT interval
• Congenital long QT syndrome
• Underlying cardiac abnormalities
• Hypothyroidism
• Females
• Patients with stroke
Here is a review article on the topic.
Long QT syndrome: diagnosis and management. Khan IA. Am Heart J. 2002 Jan;143(1):7-14
http://www.ncbi.nlm.nih.gov/pubmed/11773906
* The term “torsade de pointes” means “twisting around the points in ballet where the dancer rotates around an imaginary axis. On the ECG, the QRS complex appears to twist around the electrical baseline with a continuously changing point of origin, reminiscent of the ballet movement.
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