Optimal administration dosage of magnesium sulfate for torsades de pointes in children with long QT syndrome.
BACKGROUND
Intravenous administration of magnesium sulphate (MgSO(4)) is a very effective and safe treatment for torsades de pointes (TdP) associated with acquired long QT syndrome (LQTS) in adults. Discussed here is the efficacy of MgSO(4) for TdP in children with congenital and acquired LQTS.


METHODS
The optimal MgSO(4) dosage and serum magnesium (SMg) was determined in six consecutive children with TdP; four had congenital LQTS and two had acquired LQTS. A bolus injection of MgSO(4) was given intravenously over 1 to 2 minutes followed by continuous infusion for the next 2 to 7 days.


RESULTS
Of the six patients, five responded completely to the initial bolus of 6.1 +/- 4.2 mg/kg (range, 2.3-12 mg/kg). One (a neonate with congenital LQTS) required a total of 30 mg/kg until complete TdP elimination. Continuous infusion was given at rates of 0.3 to 1.0 mg/kg/hr with no recurrence of TdP. SMg concentration was 3.9 +/- 1.0 mg/dL (2.9-5.4 mg/dL) immediately after bolus injection.


CONCLUSIONS
Intravenous MgSO(4) infusion effectively treated TdP in children with LQTS. Optimal bolus dosage, infusion rates and SMg concentration were 3 to 12 mg/kg, 0.5 to 1.0 mg/kg/hr and 3 to 5 mg/dL, respectively.
Hoshino
Kenji
K
Pediatric Cardiology, Saitama Children's Medical Center, 2100 Magome, Iwatsuki City, Saitama 339-8551, Japan. a0182608@pref.saitama.jp
Ogawa
Kiyoshi
K
Hishitani
Takashi
T
Isobe
Takeshi
T
Eto
Yoshikatsu
Y
D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007262:Infusions, Intravenous; D007275:Injections, Intravenous; D008274:Magnesium / Q000097:blood*; D008278:Magnesium Sulfate / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D016171:Torsades de Pointes / Q000097:blood / Q000151:congenital / Q000188:drug therapy*; D016896:Treatment Outcome
D000889:Anti-Arrhythmia Agents; D008278:Magnesium Sulfate; D008274:Magnesium