Developmental anatomy and origins of LSVC
When the right atrium is developing at the eighth week of gestational
stage, the sino-atrial chamber differentiates into the sinus venosus and
the atrial chamber. The cephalic portions of the anterior cardinal veins
form the internal jugular veins while the caudal portions of the right
anterior and a part of the corresponding common cardinal vein form the
normal right-sided superior vena cava. The left anterior cardinal vein,
caudal to the innominate vein, obliterates to form “the ligament of
Marshall”, which was described as a “vestigial fold of pericardium”
(6).
The left common cardinal vein normally persists as coronary sinus and
oblique vein. The congenital malformation LSVC represents the
persistence of the left anterior cardinal vein that continues into the
left sinus horn (left duct of Cuvier) during the early developmental
period (6).
Subaortic membrane remains an important differential diagnosis in
hypertrophic cardiomyopathy with left ventricular outflow tract (LVOT)
obstruction and in aortic stenosis. The coexistence of subaortic
membrane and persistent SVCs is very rare.