Hypoplastic Left Ventricle and Scimitar Syndrome

Surgical and Cardiac Catheterization Outcomes of Scimitar Syndrome Patients: A Three Decade Single-Center Experience

Scimitar syndrome (SS) is a rare congenital condition which includes partial anomalous pulmonary venous return (PAPVR) and a variable degree of pulmonary hypoplasia. We describe the clinical features, therapeutic approach and outcomes of patients who underwent cardiac catheterization and/or surgical repair of the scimitar vein at a single institution in the United States. This retrospective cohort study included all patients with SS who underwent scimitar vein surgical repair or cardiac catheterization from October 1989 through August 2021 in a tertiary care center. A total of 84 patients with SS were included and median follow-up time was 74 months. Patients diagnosed with SS under the age of one year had a significantly greater incidence of congenital heart defects (CHD) (p < 0.001), non-cardiac anomalies (p = 0.02), pulmonary hypertension (p = 0.02), and mortality (p = 0.04) compared to those diagnosed over the age of 1 year. Twenty-eight patients underwent surgical repair of the scimitar vein. Overall, eight (10%) patients died. Compared to surviving patients, deceased patients had a significantly higher incidence of pulmonary hypertension (PH), neonatal SS diagnosis, and extracorporeal membrane oxygenation (ECMO) support. Median scimitar vein pressure (20 mmHg) of deceased patients was significantly higher compared to pressures in surviving patients (11 mmHg; p = 0.02). PH, CHD, neonatal SS diagnosis, ECMO support, and markedly elevated scimitar vein pressure are associated with mortality. Scimitar vein surgical repair during infancy is commonly associated with PH and restenosis that requires re-intervention.

Fetal Diagnosis of Scimitar Syndrome in the Presence of Complex Congenital Heart Disease

Fetal diagnosis of scimitar syndrome requires a high index of suspicion. We present two fetal cases of complex congenital heart disease associated with scimitar syndrome, one of them is diagnosed with scimitar syndrome in utero. We emphasize prenatal echocardiographic findings that may assist with arriving at the correct prenatal diagnosis. We also discuss potential challenges in suspecting the presence of scimitar syndrome in utero. The postnatal echocardiographic findings and course are described for both patients. We reviewed the available literature on prenatal diagnosis of scimitar syndrome in the presence of complex congenital heart disease. We describe a new association of VACTERL, imperforate anus, scimitar syndrome, and double-outlet right ventricle all on the same patient, as well as the first prenatal diagnosis of scimitar syndrome associated with hypoplastic left heart syndrome with restrictive atrial septum. Advanced imaging modalities such as a fetal lung Magnetic Resonance Imaging is suggested as a confirmatory test when scimitar syndrome is suspected in utero in the presence of complex congenital heart disease.

Surgical management of the scimitar syndrome

BACKGROUND AND AIM

We sought to address the varied anatomical details, the diagnostic challenges, associated cardiopulmonary anomalies, the techniques, and outcomes of management, including re-interventions of scimitar syndrome.

METHODS

A total of 92 published investigations of scimitar syndrome were reviewed. Diagnostic information was provided by clinical presentations, radiographic findings, transthoracic and transesophageal echocardiography, computed-tomographic angiography, magnetic resonance imaging, angiocardiography, and ventilation/perfusion scans. These investigations served to elucidate the origin, course, and termination of the scimitar vein, the intracardiac anatomy, the presence of associated defects, and the patterns of any accompanying pulmonary lesions prior to surgical intervention.

RESULTS

Of the patients described, up to four-fifths presented during infancy, with cardiac failure, increased pulmonary flow, and pulmonary hypertension. Associated cardiac and extracardiac defects, particularly hypoplasia of the right lung, are present in up to three-quarters of cases. Overall operative mortality has been cited between 4.8% and 5.9%. Mortality was highest in patients with preoperative pulmonary hypertension, and those undergoing surgery in infancy. Despite timely surgical intervention, post-repair obstruction of the scimitar vein, intra-atrial baffle obstruction, or stenosis of the inferior caval vein were reported in up to two-thirds of cases. The venous obstruction could not be related to any particular surgical technique. On long term follow-up, one sixth of patients reported persistent dyspnoea and recurrent respiratory infections.

CONCLUSIONS

Any infants presenting with heart failure, right-sided heart, and hypoplastic right lung should be evaluated to exclude the syndrome. An increased appreciation of variables will contribute to improved surgical management.

Asymptomatic atresia of the anomalous pulmonary vein in a patient with scimitar syndrome presenting in childhood

An asymptomatic 6-year-old boy with a history of right lung hypoplasia was referred for cardiology evaluation. Echocardiography demonstrated right pulmonary artery hypoplasia with flow reversal in that vessel. The right pulmonary veins were not visualised in the echocardiogram. Cardiac catheterisation confirmed the diagnosis of scimitar syndrome with a characteristic large vertical vein; however, the right pulmonary veins were found to be atretic with no connection to the heart with decompression through the azygos vein. In all, four systemic to pulmonary arterial collaterals were identified, supplying the right lung, which were occluded using embolization coils. This case demonstrates the potential for progressive stenosis and atresia of the so-called "scimitar vein" without previous surgical instrumentation, and that this can occur without haemodynamic embarrassment or development of pulmonary vascular disease.