Persistent left superior vena cava

Clinical History

A 72-year-old man underwent, in our institution, a cardiac-MRI examination before RF ablation for atrial fibrillation.

Imaging Findings

MRI examination was performed to depict the pathoanatomic structure of the pulmonary veins (Fig. 2) and to measure the cardiac chambers dimensions with a MRI standard post-processing workstation. Contrast-enhanced images were acquired using 1.5 Tesla scanner. As occasional finding a Persistent Left Superior Vena Cava was found.

Discussion

Persistent left superior vena cava (PLSVC) is a relatively rare congenital venous anomaly occurring in approximately 0.3% to 0.5% of the normal population and 2.8% to 4.3% of patients with congenital heart disease [1]. It is the most common congenital anomaly of the systemic veins.

The thoracic embryonic venous system is composed of two large veins: the superior cardinal veins (right and left) which return blood from cranial aspect of embryo, and the inferior cardinal vein (right and left) which returns blood from the caudal aspect. During the 8th week of gestation, an anastomosis forms between the right and left superior cardinal veins resulting in the innominate vein and the left common cardinal vein persists to form coronary sinus. The caudal portion of right superior vein forms the normal right-sided superior vena cava, while the portion of the left superior cardinal vein normally regresses to become "ligament of Marshall" (Fig. 1). If this normal regression of the left superior cardinal vein fails to occur, a PLSVC results (Fig. 3).
Variations have been reported in the insertion of LSVC (Fig. 1). In 92% of individuals, the PLSVC drains into the right atrium via the coronary sinus (Fig. 4, 5) with no haemodynamic consequence [2]:
-Type I: left and right SVCs;
-Type II: no right superior vena cava (RSVC) (18%).
In the remaining 8% LSVC drains into the left atrium:
-Type III: the atrial septum is intact;
-Type IV: posterior atrial septal defect, which allows a left-to-right shunt at atrial level. The bridging innominate vein may be present or absent.
Other associated congenital cardiac defects (atrial and ventricolar septal defects, bicuspid aortic valve, coarctation of aorta, coronary sinus ostial atresia and tetralogy of Fallot) and rhythm disturbances (sick sinus syndrome, sinus bradycardia, and sudden death) may be detected in this patients [3].

Diagnosis of LSVC is usually made as an incidental finding during cardiovascular imaging or surgery. A PLSVC can cause problems during central venous catheterisation, pacemaker implantation or cardiopulmonary bypass.
Transthoracic echocardiography reveals a dilated coronary sinus and diagnosis can be confirmed after contrast material infusion into a left arm vein [1]. There will be an enhancement of the dilated coronary sinus, before the right atrium, or the enhancement of the left atrium (for the TYPE III or IV). Multislice computed tomography or MRI can also be employed to establish the diagnosis, and is useful to rule out variations in the typical anomalous venous course.
Treatment is required for isolated lesion [1].

Differential Diagnosis List

Final Diagnosis

Persistent left superior vena cava drains into the right atrium, with no RSVC.

URL:	https://www.eurorad.org/case/10453
DOI:	10.1594/EURORAD/CASE.10453
ISSN:	1563-4086