A Scimitar Syndrome Variant Associated with Critical Aortic Coarctation in a Newborn

Background

Scimitar syndrome (SCS) is a rare congenital malformation, characterized by partial or total anomalous pulmonary venous return from the right lung, pulmonary hypoplasia, and aortopulmonary collateral arteries [1–5]. Pulmonary hypertension is a common finding and a poor prognostic sign. The combination of SCS and aortic coarctation is extremely rare, and only a few cases have been described in the literature [6]. With this combination, clinical manifestations at birth vary and can range in severity from no symptoms to respiratory distress and heart failure. The prognosis depends on the extent of pulmonary hypoplasia, the degree of pulmonary hypertension, and the outcomes of cardiac surgery and interventional procedures [1–5].

In this report, we discuss the case of a female newborn with an unusual association between an SCS variant and aortic coarctation, which resulted in challenging diagnostic observations and a complex clinical course.

Case Report

The patient was the third child of a 33-year-old, non-smoking, healthy mother who was regularly monitored during her pregnancy. Amniocentesis showed no genetic abnormalities, including DiGeorge syndrome. A morphological ultrasound scan performed at 24 weeks’ gestation demonstrated intrauterine growth restriction (IUGR) and oligohydramnios. The mother was hospitalized at 28 weeks’ gestation for corticosteroid treatment. Fetal echocardiography showed an enlarged right ventricle and pericardial effusion. Because of the IUGR, delivery was induced at 36 weeks’ gestation. The newborn weighed 2040 g and had Apgar scores of 8 at 1 and 5 minutes. The early postnatal period was uneventful and the newborn was discharged from the maternity hospital in good clinical condition 14 days after birth.

At age 21 days, the newborn was examined and found to be in extremely poor clinical condition, with signs of cardiogenic shock, tachycardia, hepatomegaly, pallor, mottled skin, absence of peripheral pulse, prolonged capillary refill (over 6 seconds) and periodical apnea. A chest X-ray showed cardiomegaly, dextroposition of the heart, and relative right lung hypoplasia (Figure 1). Echocardiography revealed a 4-mm hypoplastic left aortic arch, aortic coarctation with narrowing of the isthmus to 1.5 mm and a posterior shelf (Figure 2), closed ductus arteriosus, bicuspid aortic valve, enlarged right ventricle, decreased systolic function in both ventricles, mild pulmonary hypertension, and mild pericardial effusion. The left pulmonary veins drained into the small left atrium near the septal region, while there were anomalous retrograde venous drainage into the inferior vena cava and no connection between the right pulmonary veins and the left atrium (Figure 3). The newborn was intubated and treated with prostaglandin E and cardio-tonic and decongestive agents. Because of her poor clinical condition, oliguria, and increased lactate levels, resection of the coarctation segment and extended end-to-end anastomosis was performed a few hours later.

Soon after the surgery, the newborn’s clinical condition and echocardiography findings improved (Figure 4). Because of persistent pulmonary hypertension, sildenafil was administered. To evaluate pulmonary venous drainage, a computed tomography angiography was performed. Congenital pulmonary venolobar syndrome (scimitar syndrome) was diagnosed, which consisted of anomalous drainage of the right upper pulmonary vein into the superior vena cava and of the right lower pulmonary vein into the inferior vena cava; right lung hypoplasia; dextroposition of the heart; and intrapulmonary sequestration in the right lower lobe supplied by the systemic artery from the celiac trunk (Figures 5, 6). When the patient was age 5 weeks, interventional catheterization was performed in coordination with the referring center (Motol University Hospital, Prague, Czech Republic) and showed a mean pressure in the pulmonary artery of 27 mmHg. The aortopulmonary collateral artery then was occluded completely with an AMPLATZER™ Vascular Plug 4. After the procedure, chylous pleural effusion was noted around the left lung and the pleura was drained. Prolonged treatment with vancomycin and cefotaxime was administered after the patient’s blood culture showed Staphylococcus epidermidis and infective endocarditis was suspected because she had an indwelling catheter and increased levels of C-reactive protein. The patient was discharged at age 4 months in clinically good condition with no pulmonary hypertension. Her clinical course was uneventful at 1-year follow-up.

Discussion

The incidence of SCS is 1 to 3 per 100 000 live births and its clinical presentation in children is variable [1]. Up to half of patients with it are symptomatic and present within the first 6 months of life [7]. The anomalies most commonly associated with SCS are atrial septal defect, ventricular septal defect, patent ductus arteriosus, anomalous origin of the coronary artery from the pulmonary trunk, persistent left superior vena cava drainage into the coronary sinus, and coarctation of the aorta [7–9]. Symptomatic infants with SCS typically have associated anomalies, and aortic coarctation can be expected in 10% of them. Treatment of SCS includes conservative therapy, surgical repair, occlusion of collateral arteries, pneumonectomy, and lung transplantation. Up to one-third of infants with SCS who are symptomatic die. In the case presented here, we decided to perform interventional embolization of the aortopulmonary collateral artery because the patient was on prolonged mechanical ventilation; the result was optimal.

Half of patients who are diagnosed with SCS after infancy remain asymptomatic, and the condition is an incidental finding, based on seeing the characteristic “Turkish sword” in the right lung on chest X-ray. Approximately 18% of patients with SCS have variants that differ from the classical appearance (anomalous drainage of the right pulmonary vein into the inferior vena cava and aortopulmonary collateral arteries in the right lung) [8]. The variant described in our patient, with anomalous total right pulmonary venous drainage into the superior and inferior vena cava, can be expected in 2% of cases of SCS.

Diagnosis of critical congenital heart disease (CHD) is based on 3 screening methods: prenatal ultrasound, clinical examination after birth, and pulse oximetry. In Slovenia, 90% of heart anomalies are diagnosed in timely fashion using these 3 methods [10]. In our case, all 3 screening methods were applied, but the patient’s CHD was not diagnosed. Left-sided, obstructive CHD is known to present the greatest screening challenge, and sometimes it cannot be diagnosed in the first days of life. Normal hemodynamic processes result in closure of the ductus arteriosus between the second and fourth weeks after birth, which can lead to severe heart failure or even death [10]. Timely diagnosis of critical heart anomalies in newborns is of great importance because it reduces mortality, and additional screening and pulse oximetry at age 2 to 3 weeks may be warranted. In our case, closure of the ductus arteriosus on the basis of aortic coarctation and scimitar syndrome led to severe heart failure and a life-threatening situation. The patient’s clinical condition was worsened by pulmonary hyper-tension, which could have been related to the coarctation and SCS -related pulmonary hypoplasia. However, because our patient was in such poor condition, it was not possible to evaluate the SCS variant before the aortic surgery. We concluded that hemodynamic compromise and pulmonary hypertension were mainly associated with the critical coarctation and decided to postpone a complete diagnostic evaluation of the right pulmonary venous drainage until after surgery.

Conclusions

SCS with critical aortic coarctation is a very rare form of CHD in neonates. An association of the variant of SCS and coarctation of the aorta as described in our patient has never been reported in the literature before. In general, presentation of SCS in infancy with heart failure, pulmonary hypoplasia, and hypertension is associated with a poor prognosis [6]. A diagnosis of SCS should be considered when pulmonary hyper-tension persists after coarctation repair in a child with dextroposition of the heart and right lung hypoplasia. Successful treatment of this rare combination calls for teamwork by highly experienced specialists.