Persistent Left Superior Vena Cava with Absent Right Superior Vena Cava and Coronary Sinus Dilation Mimicking a Paracardiac Mass

A 54-year-old man was referred to our hospital due to atypical chest pain and a suspected paracardiac mass. Cardiac examination revealed a grade 1/6 systolic murmur in the left parasternal border. Results of surface electrocardiography and laboratory examinations were within normal limits.

Transthoracic (Fig. 1) and transesophageal echocardiography showed the absence of a right superior vena cava (SVC), the presence of a left SVC at the lateral border of the left atrium, and no other structural abnormalities. The diagnosis was confirmed on computed tomography (CT) (Fig. 2). The patient's visceral organs were normally positioned and structured. Coronary angiography and cardiac catheterization revealed normal coronary arteries and no stenosis. Upper-extremity and cranial veins drained into the coronary sinus via the persistent left SVC; therefore, the coronary sinus was approximately 5 cm in diameter and mimicked a paracardiac mass (Fig. 3).

Fig. 1 The dilated coronary sinus (arrows) resembles a paracardiac mass, as shown on transthoracic 2-dimensional echocardiography in the apical 5-chamber view. Ao = aorta; LA = left atrium; LV = left ventricle

Fig. 2 Computed tomography of the chest shows the persistent left superior vena cava (arrow) next to the aortic arch (Ao).

Fig. 3 Coronary sinus angiography shows retrograde opacification via the coronary sinus of the persistent left superior vena cava in the left lateral thorax.

Comment

Persistent left SVC, an anomaly of the venous circulation, occurs in 0.5% of the general population, 0.3% of healthy persons, and 4.3% of those with congenital heart disease.^1–4 In most patients with left SVC, a right SVC is present. Persistent left SVC with absent right SVC occurs in only 0.09% to 0.13% of patients who have congenital heart defects.⁵ Although this rare condition is frequently associated with situs inversus, our situs solitus patient lacked a right SVC and had a persistent left SVC that drained into the right atrium via an extremely dilated coronary sinus. The sinus was even larger than that usually seen in the more common left-SVC persistence with right SVC; this was likely due to the rarer associated agenesis of the right SVC in this patient.

Persistent left SVC, and other anomalies and structures in the left atrioventricular groove, can be overlooked if they are not carefully and appropriately evaluated. Venous angiography is a widely available and low-cost imaging method for early confirmation of the presented combined venous malformation. Angiography and CT were useful in this case, because right-SVC agenesis would not necessarily be suspected.