Not all right-sided hearts are the same-the importance of identifying the correct diagnosis

Abstract

Scimitar syndrome is characterized by an anomalous venous return with the characteristic chest roentgenogram (CxR) appearance of the anomalous vein draining into the inferior vena cava (IVC). This appears as a curvilinear opacity paralleling the right border of the heart resembling a curved sword or Scimitar. A 27-year-old white woman with a reported history of dextrocardia was admitted after a drug overdose. Examination demonstrated an obtunded woman with tachycardia and right sided heart sounds. Her CxR revealed a right sided heart image with two curvilinear opacities in the retrocardiac area. Chest computed tomography (CT) demonstrated that these opacities join to represent an anomalous vein draining into IVC. Furthermore, an anomalous systemic artery arising from the abdominal aorta was seen to supply the right lower lobe. The patient was eventually diagnosed with Scimitar syndrome. This syndrome affects 1-3 in 100,000 live births while nearly half of the patients remain asymptomatic with some initially being misdiagnosed as dextrocardia, such as in our case. Correctly diagnosing these patients is of paramount importance as some can develop severe pulmonary hypertension and right ventricular failure. In turn, close ongoing echocardiographic monitoring can help identify those that may benefit from surgical interventions to prevent them from developing these complications.

Keywords: Partial anomalous venous return; Scimitar syndrome; congenital pulmonary venolobar syndrome (CPVS); dextrocardia.

Figure 1

Frontal chest radiograph demonstrates characteristic features of Scimitar syndrome, including an asymmetrically smaller right lung with reduced pulmonary vascularity relative to the left lung, a right-sided cardiac shadow, and vertically oriented tubular densities overlying the cardiac shadow representing the scimitar veins in this case.

Figure 2

Axial CT image demonstrating a hypoplastic right lung and hypoplastic right pulmonary artery (arrow). CT, computed tomography.

Figure 3

Axial CT image demonstrating right-sided positioning of the morphologic right ventricle as defined by the moderator band (arrow), indicating this is dextropositioning of the heart consequent to right lung hypoplasia, rather than dextrocardia. CT, computed tomography.

Figure 4

Coronal minimum-intensity projection demonstrating right lung hypoplasia and anomalous right lung bronchial anatomy mirroring left bronchial anatomy (left bronchial isomerism).

Figure 5

Volume rendered right posterior oblique view demonstrating hypoplastic right pulmonary artery branches (thick black arrow), the anomalous right pulmonary (Scimitar) veins draining to the suprahepatic IVC (thin black arrows), and a systemic artery supplying the right lower lobe arising from the abdominal aorta (thin white arrows). IVC, inferior vena cava.

Figure 6

In this case the patient has dextroposition of the heart in which there was normal alignment of the major axis of the heart. The echocardiogram views were done with the echo probe on the right side of the sternum.