The pericardial sinuses are impressions in the
pericardial sac formed between the points where
great vessels enter it.
Pericardial sinus
Posterior wall of the pericardial sac, showing the lines of reflection of the serous
pericardium on the
great vessels. (Transverse sinus labeled at center. Oblique sinus not labeled, but visible inferior to transverse sinus between the right and left
pulmonary veins)
The transverse sinus is the tunnel-shaped passage posterior to the
aorta and
pulmonary trunk , and anterior to the
superior vena cava.[1][2] This sinus is clinically important because passing one end of clamp through the sinus, and the other end anterior to the aorta/pulmonary trunk will allow complete blockage of blood output. This is performed during some
heart surgeries.[citation needed]