Teaching Case

A 34 years old male with a history of asthma presented at the emergency department with new onset of exertional dyspnea and right-sided respiratory-related thoracic pain. Vital signs, including saturation, were normal. Blood results showed limited inflammation with C-Reactive Protein (CRP) of 33mg/L and a normal white blood cell (WBC) count.

Because of clinical suspicion of pneumonia, a non-contrast-enhanced computed tomography (NECT) was performed. Centrilobular micronodules with a tree-in-bud pattern were seen in the posterior segment of the left lower lobe, consistent with infectious changes.
An incidental finding of an accessory vascular structure in the mediastinum on the left side, connecting the left brachiocephalic vein to the left superior pulmonary vein, was made. (Figures 1 and 2).

Background

A levoatriocardinal vein or vertical vein is a rare pulmonary-systemic connection, mostly occurring in left-sided obstructive lesions, such as hypoplastic left heart syndrome, where it provides an alternative outflow for pulmonary venous blood. [1,2] The presence of a levoatriocardinal vein can also occur without associated cardiac malformation, although this is even more rare. [1-4] In this case, the vein mostly functions as a left-right shunt proximal to the tricuspid valve but can be bidirectional as well. [3,5] Its origin is thought to be the persistence of anastomotic channels connecting the capillary plexus of the embryonic foregut, which serves as a precursor to the pulmonary veins, to the cardinal system. [1,3]

Clinical Perspective

Symptoms are mostly determined by the associated cardiac abnormalities. In case of an isolated levoatriocardinal vein with a left-right shunt, there may be development of progressive dilatation of the right heart and pulmonary hypertension. [5] In case of a bidirectional shunt there can be symptoms of paradoxical embolisms, such as transient ischemic attacks or strokes. [3]
Patients may present with an asymptomatic murmur. [3]

Imaging Perspective

A levoatriocardinal vein can be evaluated by means of echocardiography, CT scan or magnetic resonance imaging. Its presence is diagnosed by demonstrating an anomalous vein that connects the left atrium or a pulmonary vein to a systemic vein. This pulmonary vein should be connected to the left atrium. The most frequent systemic vein in which a levoatriocardinal vein drains is the left brachiocephalic vein, followed by the vena cava superior and less commonly the jugular veins. Its course is mostly lateral to the aortic arch. [3]

The differential diagnosis must be made with a persistent left superior vena cava (PLSVC). A PLSVC usually drains into the coronary sinus and shows no shunting connection with the pulmonary system. [6] An anomalous pulmonary venous connection might also be confused with a levoatriocardinal vein. However, an anomalous pulmonary vein has no normal connection to the left atrium. [3]

Outcome

In case of an isolated levoatriocardinal vein without associated cardiac malformation, the left-right shunt is usually small and does not need to be treated. In case of a bidirectional shunt with symptoms of paradoxical embolisms, the vein can be closed with a vascular plug. [3]
When associated cardiac malformations are present, such as hypoplastic left heart syndrome, more complex surgery is needed to correct the underlying abnormality. [3]
The levoatriocardinal vein may present a problem if right-sided pneumectomy is needed because this may increase the volume of the shunt resulting in right-sided heart failure and restricts the resultant functional parenchyma to the left lower lobe as oxygenated blood from the left upper lobe returns to the right heart.  [7]

Take Home Message / Teaching Points

A levoatriocardinal vein is a rare entity and knowledge of its origin and imaging appearance facilitates its diagnosis. Management is determined by the direction of the shunt and associated cardiac malformations.

Written informed consent was obtained.