Case report

This was a dichorionic diamniotic twin pregnancy involving one healthy twin, and in one of the Di-Di twins congenital heart disease was found.

This cardiac defect was detected by the referring obstetrician at 13 weeks’ gestation on two-dimensional ultrasonography. Amniocentesis and genetic testing revealed no abnormalities. The patient was followed by the Twin Pregnancy Outpatient Clinic at our institute and was referred for targeted fetal echocardiography at 26 weeks’ gestation.

Targeted fetal echocardiography at our centre demonstrated a structurally normal four-chamber view of the heart; however, cardiomegaly and myocardial hypertrophy were present, and ventriculoarterial discordance suggesting transposed great arteries (TGA) (Figures 1-3). In sagittal view, d-TGA was confirmed by images of the parallel great vessels (Figure 4), together with a narrowed aortic isthmus (Figure 5) on longitudinal imaging and colour Doppler assessment. No flow reversal was observed at the aortic isthmus. Hyperkinetic motion of the foramen ovale flap (Figure 6) was also present, representing a fetal echocardiographic marker of the potential need for balloon atrial septostomy (Rashkind procedure) on the first day of postnatal life.

The final fetal echocardiographic examination was performed at 35 weeks’ gestation, and a follow-up examination was scheduled 2 weeks later. However, prelabour rupture of membranes occurred at 37 weeks’ gestation, and caesarean delivery was performed. The affected neonate weighed 2650 g, had a pH of 7.23, a base excess of –1.5, and received an Apgar score of 9. The healthy female co-twin weighed 2880 g and received an Apgar score of 10. An intravenous line was placed, and a Prostin infusion at 0.01 mg/kg/min was initiated. Approximately 30 min later, the affected neonate became cyanotic, required endotracheal intubation and mechanical ventilation, and was urgently transferred to the cardiac catheterisation laboratory for a Rashkind procedure.

On day 7 of life, the patient underwent an arterial switch operation (ASO). During the postoperative course, sporadic extrasystoles were observed and responded well to intravenous magnesium. On day 14 of life, computed tomography angiography showed an aortic isthmus diameter of 2.5 mm (Figures 7, 8). The patient was therefore transferred back to the cardiac catheterisation laboratory for stent implantation. He was extubated the following day and received antibiotics. On day 27 of life, he was discharged home to join his healthy co-twin. Follow-up echocardiography demonstrated good left ventricular contractility.

Discussion

A patent ductus arteriosus in a newborn often hides the potential for a coarctation, and we do not rule out coarctation when there is a PDA in a newborn study [1]. Coarctation may become evident at a 6-month follow-up to the ASO [2].

We report herein about the possibility to make such a detailed diagnosis based on fetal echocardiography.

Hence, it is worth remembering that even in a dichorionic diamniotic twin pregnancy without major intertwin biometric differences, congenital heart disease may affect only one twin. ​Identification of one cardiac abnormality (in this case, d-TGA) does not exclude an additional lesion, such as coarctation of the aorta (CoA).

Prenatal referral to a specialised fetal cardiac centre and close multidisciplinary collaboration among fetal cardiologists, neonatologists, paediatric cardiac surgeons, and interventional paediatric cardiologists can contribute to a favourable outcome.

Disclosures

Ethical considerations: none.

This research received no external funding.

The authors declare no conflict of interest.