Left Superior Vena Cava
Persistent left superior vena cava (LSVC) is usually an incidental finding during echocardiography, cardiothoracic surgery or autopsy. Echocardiographic findings of LSVC include dilation of the coronary sinus in absence of right atrial enlargement and increased right atrial pressures. The dilated coronary sinus can protrude into the left atrium, sometimes being mistaken for a left atrial mass. The diagnosis is definitively confirmed by contrast echocardiography. With injection of agitated saline or contrast in a left arm vein, contrast should first appear in the coronary sinus, followed by opacification of the right atrium. Injection of echo contrast into a right arm vein should opacify the right atrium but not the coronary sinus.
NOTES: Persistent LVSC
Clinical Issues
Persistent left superior vena cava (LSVC) is seen in 0.3 to 0.5 % of the normal population and 3 to 10 % of patients with other congenital heart abnormalities. It is a persistent remnant of a vessel that is present as an embryological counterpart of the normal right-sided superior vena cava.
Blood returning from the left upper extremity and head through the left subclavian and left internal jugular veins drain into the LSVC to the coronary sinus and thence into the right atrium. The coronary sinus dilates secondary to this large volume of blood. The left innominate vein is either absent or small.
If it is not associated with other congenital anomalies, it is usually asymptomatic and hemodynamical ly insignificant. However, LSVC has important clinical implications in certain situations. PLSVC may complicate placement of cardiac catheters or pacemaker leads. Awareness of this anomaly may reduce confusion about the position of a catheter/lead that appear to have strayed.
During cardiac surgery, PLSVC is a relative contraindication to retrograde administration of cardioplegia. The coronary sinus catheter balloon may not be able to occlude the dilated coronary sinus, resulting in the failure to ensure retrograde flow of cardioplegia to the myocardium. Also cardioplegia delivered would largely be distributed to the left internal jugular and left subclavian veins,rather than myocardium. The coronary sinus would have to be carefully dissected during heart transplant so that the PLSVC can be reanastomosed to the right atrium.
Long axis view of the left ventricle shows the very enlarged coronary sinus in the A-V groove which is characteristic of a persistent left superior vena cava.
lsvc_mri MRI images in coronal (arrow) and axial views (labelled arrow) show the persistent left superior vena cava (LSCV). The location of the conventional right-sided SVC is shown on the axial image
Xray after insertion of a left subclavian vein catheter shows the course (arrows) along the left cardiac border and then turning horizontally as it traverses the coronary sinus into the right atrium.
Apical 4 chamber view of the patient whose xray shows the central line, shows the bright linear horizontal signal in the coronary sinus just behind the mitral annulus.
TEE view of the left atrium (LA) shows the indentation of the enlarged coronary sinus caused by the bloodflow contributed by the persistent left superior vena cava (LSVC).
