Fetal Presentation of Congenital Long QT Syndrome

Abstract

Thirty-two-week prenatal ultrasound revealed a fetal heart rate of 100 bpm with decreased variability on the heart rate tracing. Echocardiogram documented normal anatomy and sinus bradycardia. Newborn electrocardiogram revealed sinus rhythm at 100 bpm with a QTc of 0.657. Follow-up electrocardiogram revealed a QTc interval of 0.568, 2:1 atrioventricular block with a ventricular rate of 60 bpm, and ventricular ectopy. The infant received a pacemaker and beta-blocker therapy. Long QT syndrome should be in the differential diagnosis of the fetus with bradycardia and decreased heart rate variability in the absence of distress. Early diagnosis allowed for preventative care in the infant and identification of family members at risk.

Prenatal diagnosis of sustained bradycardia with 1 : 1 atrioventricular conduction

“…Wandering pacemaker was another cause of this type of fetal bradycardia. Although we did not experience this in our study, a recent report showed that some neonates with long QT syndrome had had bradycardia with 1 : 1 atrioventricular conduction during the prenatal period15, 16.…”

Fetal Presentation of Long QT Syndrome – Evaluation of Prenatal Risk Factors: A Systematic Review

“…In particular, attention should be paid to fetuses with a slightly reduced FHR of 110–120 bpm as well as fetuses with bradycardia <110 bpm, tachyarrhythmias or clinical signs of heart failure, such as pleural effusion and hydrops. As shown in cases 6, 9, 10 and 11 in table 1, some fetuses with LQTS exhibit a reduced heart rate variability [6,9,10,11]. Fetal magnetocardiography is able to detect the prolongation of the QT interval [9,11,14,20] as well as subtle changes in the short-term heart rate variability [41], thereby facilitating the prenatal diagnosis of LQTS [9,11,14,20].…”

“…The search terms ‘long QT syndrome’, ‘fetal arrhythmia’ and ‘congenital heart disease’ were used. The 30 reports were classified into three categories according to content: 20 reports [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21] describing 21 patients with LQTS documented abnormal cardiac findings found in utero (table 1); 5 reports [23,24,25,26,27] described series of LQTS patients and included prenatal cardiac findings for some of the fetuses (table 2), and 5 reports [28,29,30,31,32] described series of fetuses, some of whom were subsequently diagnosed as having LQTS, for whom echocardiography examinations had been performed because of abnormal cardiac findings detected incidentally during antenatal care (table 3). …”

“…LQTS accounts for more than 10% of the causes of sudden infant death syndrome [1]. Although several reports have described the prenatal cardiac findings of single or multiple cases of LQTS [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21], some patients with LQTS show only a slightly reduced baseline fetal heart rate (FHR) of 110–120 bpm in utero, as shown in figure 1. Since some fetuses with LQTS die in utero or during the neonatal period and because effective measures exist that are capable of preventing life-threatening episodes, such as syncope and ventricular tachycardia [1], antenatal diagnosis or a suspicion of LQTS may be helpful for improving the outcomes of fetuses with LQTS.…”

Arrhythmia Pharmacogenomics: Methodological Considerations

“…In general, these studies have involved small numbers of cases of SCD, and have not been replicated [72]. A number of reports indicate that that monogenic arrhythmia syndromes can present as the Sudden Infant Death Syndrome (SIDS) [73–75]. …”