Torsades de pointes risk factors
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Long QT syndrome is a risk factor for developing torsades de pointes, and can either be inherited as congenital mutations of ion channels carrying the cardiac impulse/action potential, or acquired as a result of drugs that block these cardiac ion currents. Other risk factors include electrolyte abnormalities, heart failure, left ventricular hypertrophy, female gender or renal and liver failure. Being on certain medications also pose a risk for developing torsades de pointes.
Risk Factors
Factors that are associated with an increased tendency toward torsades de pointes include:
- Familial long QT syndrome
- Class IA antiarrhythmics
- Hypomagnesemia
- Hypokalemia
- Hypoxia
- Acidosis
- Heart failure
- Left ventricular hypertrophy
- Slow heart rate
- Female gender
- Baseline electrocardiographic abnormalities
- Renal failure or liver failure
Clinical Correlation
- Drugs: quinidine, PCA, norpace, amiodarone, phenothiazines, tricyclic antidepressants, pentamidine.
- with quinidine majority of the cases occur within one week of initiation, and with therapeutic levels
- Electrolyte imbalances: hypokalemia, hypomagnesemia, hypocalcemia
- CAD
- MVP
- Variant angina
- Myocarditis
- Subarachnoid hemorrhage
- Congenital QT prolongation
- Liquid protein diets
- Hypothyroidism
- because of bradycardia and a prolonged QT syndrome
- Organophosphate poisoning [1] [2]