A Patient Needs a Pacemaker,and the Cardiologist Plans to Run

Multiple Choice

A patient needs a pacemaker,and the cardiologist plans to run the pacemaker electrode into the right atrium via the left subclavian vein.As the cardiologist monitors the placement of the catheter using angiography,he discovers that the catheter will not enter the superior vena cava.Rather,it enters the coronary sinus and then the right atrium.How is this possible?

A) Right supracardinal venous system did not regress during development.
B) Patient has a left superior vena cava.
C) Patient has a patent foramen ovale.
D) Ligamentum venosum failed to close.
E) Patient has a patent ductus arteriosus.