Prenatal findings in patients with prolonged QT interval in the neonatal period.

Abstract

Objective-To describe prenatal abnormalities of cardiac rhythm in patients with prolonged QT interval in the neonatal period. Design-A retrospective analysis of the results of fetal echocardiography and the outcome in patients with prolonged QT interval in the neonatal period who had been referred for prenatal evaluation. Setting-Two university hospitals. Patients-Nine patients with prolonged QT interval in the neonatal period who had been referred for prenatal evaluation. Fetal echocardiograms were obtained from 24 to 40 weeks of gestation. Indications were fetal bradycardia (five patients), a family history of long QT syndrome (two patients), and complex arrhythmias (two patients). Results-Seven fetuses had persistent sinus bradycardia without ventricular arrhythmias (heart rates 70-120 beats/ min). Five patients were treated with propranolol, after the diagnosis had been established by postnatal electrocardiogram (ECG). One of these patients died suddenly at the age of 3 weeks, after the treatment had been stopped because of profound bradycardia. One of the remaining two patients who did not receive propranolol had a syncope at the age of 6 weeks. Two fetuses presented with frequent runs of ventricular tachycardia and intermittent bradycardia caused by intermittent, functional second degree atrioventricular block. Both patients died on the first day of life despite treatment with propranolol and transvenous temporary pacing. Conclusions-Sinus bradycardia in an otherwise normal fetus may be a symptom of long QT syndrome. Postnatal ECGs and a family emination are strongly recommended in these children. In fetuses with frequent runs ofventricular tachycardia and intermittent second degree atrioventricular block long QT syndrome should be suspected prenatally. These high risk patients should be delivered in centres with a paediatric cardiology unit.

Clinical Characteristics and Genetic Background of Congenital Long-QT Syndrome Diagnosed in Fetal, Neonatal, and Infantile Life

“…Sinus bradycardia has been considered a significant presentation of LQTS, especially in the fetal-neonatal period, 3,19,20 and is often a clue to the diagnosis of LQTS. The present study verified that sinus bradycardia is common among all types of LQTS in this age group, especially in fetal-neonatal periods.…”

“…suggest that the latter cases are at higher risk of development of life-threatening arrhythmias necessitating emergency treatment [3][4][5] and show higher mortality rates than the former age groups. 3,[5][6][7][8][9][10][11] For example, recent progress in molecular biology has clarified that LQTS partly contributes to sudden infant death syndrome (SIDS).…”

“…3,[5][6][7][8][9][10][11] For example, recent progress in molecular biology has clarified that LQTS partly contributes to sudden infant death syndrome (SIDS). 12,13 Unfortunately, prenatal diagnosis of LQTS has been extremely difficult to confirm except for a limited number of cases for which prenatal gene screening 14 or fetal magnetocardiography (fMCG) [15][16][17] was applied.…”

De Novo Mutation in the SCN5A Gene Associated With Early Onset of Sudden Infant Death

“…34 Genetic analysis of the LQTS genes in neonates is therefore recommended in those cases in whom the suspicion of LQTS is made by family history or ECG findings including QTc at birth Ͼ500 ms 1/2 or prenatal sinus bradycardia. 35,36 Sporadic cases escape early diagnosis and treatment until the infant has the first symptoms or is discovered by other medical investigations by chance.…”

Extended Fetal Bradycardia

“…Usually, an etiological factor cannot be found in sinus bradycardia cases. Prolonged fetal bradycardia may develop because of maternal drug use, which can cause fetal stress, acidosis, hypoxia, and long QT and sick sinus syndromes (6). Reported cases in the literature showed that maternal hypothermia and hypoglycemia may also cause fetal bradycardia.…”