Transverse pericardial sinus

The transverse pericardial sinus in domestic animals is a potential space within the pericardial cavity that results from the embryological folding of the serous pericardium around the arterial and venous poles of the heart. It represents a transverse passage separating the arterial outflow tracts from the venous inflow structures at the base of the heart.

The transverse pericardial sinus curves transversely across the base of the heart forming a U-shaped passage between the right and left sides of the pericardial cavity. This sinus passes between the ascending aorta and pulmonary trunk cranially and the pulmonary veins caudally.

The sinus extends laterally on both sides and can be entered by passing a finger or probe from right to left behind the arterial trunks and in front of the atrial mass.