title: Drug-induced QT-interval prolongation and recurrent torsade de pointes in a child with heterotaxy syndrome and KCNE1 D85N polymorphism.
abstract: We present a child case of heterotaxy syndrome (asplenia syndrome) after Fontan procedure that showed extreme prolongation of QT interval and torsade de pointes (TdP) after administration of sodium channel blockers for paroxysmal atrial tachycardia. Despite low serum concentration of the drugs, QT prolongation persisted and TdP attacks with unconsciousness recurred, possibly in association with junctional bradycardia and myocardial damage although he had never experienced QT prolongation during bradycardia before. Temporal cardiac pacing via a venous route to exclude possible implication of bradycardia in induction of TdP was difficult to apply due to total cavopulmonary connection (TCPC) circulation. Continuous intravenous administration of low-dose isoproterenol was started but an appropriate heart rate for prevention of TdP was difficult to obtain. Finally, we were urged to conduct implantation of a DDD pacemaker combined with ICD surgically with epicardial leads, resulting in successful suppression of TdP and syncope. Screening of the genotype disclosed the KCNE1 D85N polymorphism, which is known as one of the typical disease-causing gene variants in long-QT syndrome (LQTS).
authors.affiliation: Department of Child Health, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan. lishenglin5433@gmail.com
authors.forename: Lisheng
authors.initials: L
authors.lastname: Lin
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Horigome
authors.forename: Naoko
authors.initials: N
authors.lastname: Nishigami
authors.forename: Seiko
authors.initials: S
authors.lastname: Ohno
authors.forename: Minoru
authors.initials: M
authors.lastname: Horie
authors.forename: Ryo
authors.initials: R
authors.lastname: Sumazaki
mesh_terms: D000293:Adolescent; D059446:Heterotaxy Syndrome / Q000235:genetics*; D006801:Humans; D008133:Long QT Syndrome / Q000139:chemically induced* / Q000235:genetics*; D008297:Male; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D024642:Potassium Channels, Voltage-Gated / Q000235:genetics*; D055502:Secondary Prevention; D026941:Sodium Channel Blockers / Q000009:adverse effects*; D016171:Torsades de Pointes / Q000139:chemically induced* / Q000235:genetics*
chemical_list: C489622:KCNE1 protein, human; D024642:Potassium Channels, Voltage-Gated; D026941:Sodium Channel Blockers