a1 Pediatric Cardiology Unit, University Hospital of Nantes, Nantes, France
a2 Pediatric and Neonatal Intensive Care Unit, University Hospital of Nantes, Nantes, France
Background The association between long QT interval and sudden infant death syndrome has been clearly established. Several studies have been conducted to determine the evolution of the QT interval in childhood from birth, but only in full-term newborns. However, data on the QT interval in pre-term infants are extremely scarce. The objective was to describe the development of the QT interval in premature infants.
Material and methods In a prospective monocentric study in a neonatal intensive care unit, pre-term newborns born before 37 weeks of gestation without congenital heart disease, family history of long QT, unstable haemodynamic status, or administration of drugs inducing QT interval prolongation were included with parental consent. An electrocardiogram was recorded in similar conditions weekly until discharge in each child. The corrected QT was calculated with Bazett's formula.
Results In all, 309 echocardiograms were recorded in 87 children, with gestational age ranging from 24–36 weeks. QT first increased after birth in very premature infants – less than 30 weeks of gestation – and then started to decrease, whereas it only decreased in more mature infants. When plotted against postmenstrual age, QT first increased, and then decreased after 32 weeks.
Discussion Our data suggest that the QT interval varies with postmenstrual age in very premature infants, reaching a peak at 32 weeks. These developmental changes may induce specific vulnerability to QT-lengthening medications in premature infants. This study underlines the need for specific pharmacological studies in this population.
(Received June 15 2011)
(Accepted October 26 2011)
(Online publication December 19 2011)
c1 Correspondence to: Dr P.-E. Séguéla, Pediatric Cardiology Unit, Children's Hospital, Toulouse University Hospital, 330 Avenue de Grande-Bretagne, 31059 Toulouse Cedex 9, France. Tel: +33 234557459; Fax: +33 534558663; E-mail: email@example.com