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Background
Scimitar or pulmonary venolobar syndrome, is a rare congenital anomaly characterized by anomalous pulmonary venous drainage from the right lung below the diaphragm to the inferior vena cava (IVC), sometimes associated with partial or total anomalous pulmonary venous return at other locations (PAPVR/TAPVR). Left-sided scimitar syndrome is an extremely rare variant of this disease. This case report describes a left-sided scimitar syndrome, suspected on ECG and cardiac MRI with confirmation on cardiac CTA. It highlights the importance of considering left-sided scimitar syndrome in the differential diagnosis of patients with congenital heart defects and the need for a multidisciplinary approach for the management of such patients.

Educational Goals / Teaching Points
A 36-month-old girl, product of fraternal twin gestation from Dominican Republic, asymptomatic, presented with systolic heart murmur that was found by pediatrician during annual physical examination and referred to pediatric cardiology. ECG (2D echo) was done with nonvisualization of left pulmonary veins. Cardiac MRI demonstrated superior and inferior left pulmonary veins draining into a separate systemic vein and not to left atrium. This vein could not be traced beyond lower chest into abdomen. Cardiac CTA demonstrated PAPVR of the left lung infradiaphragmatically to the left renal vein (left-sided scimitar syndrome) without evidence of obstruction. It was associated with moderate right atrial and ventricular dilation, normal right-sided pulmonary venous return, dilated IVC, and small secundum ASD. Note was made of two lobes within the right lung and a single major fissure. The left lung appeared to have only one lobe with no major fissure.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Two-dimensional echo is the first-line diagnostic modality and can provide information on the anatomy and hemodynamics of this anomaly. However, in some cases, additional imaging modalities, such as cardiac MRI or CTA may be required to confirm the diagnosis and determine the extent of the anomaly. In this case, cardiac CTA was performed, demonstrating left pulmonary veins draining into the right IVC via left renal vein. The management of scimitar syndrome is typically surgical, with the goal of reestablishing normal pulmonary venous drainage to the left atrium. The choice of surgical approach is individualized and depends on the specific anatomy of the patient.

Conclusion
The natural history of uncorrected left-sided scimitar syndrome is not well understood. Patients with uncorrected left-sided scimitar syndrome are at a high risk of developing pulmonary hypertension (PTH), right ventricular dysfunction, and heart failure. Timely diagnosis and management can prevent the development of severe PTH and right ventricular dysfunction, which are associated with poor outcomes. Early surgical intervention can improve the prognosis of patients with scimitar syndrome and prevent the progression of the disease.