A blocked coronary sinus would block blood flow:

A) into the superior vena cava.
B) into the inferior vena cava.
C) into the pulmonary arteries.
D) returning from the pulmonary arteries.
E) returning from the coronary circulation.

Coronary Sinus

A large vein on the posterior side of the heart that collects blood from the myocardium (heart muscle) and directs it into the right atrium.

Coronary Circulation

The system of blood vessels that delivers blood to the heart muscle and returns blood from the heart muscle to the right atrium.