Obviously
The sac is called the pericardial sac. The snake's heart can move 1 to 1 1/2 inches because of this sac.
Pericardial cavity
Encloses cardiac space.
The pericardial fluid
Pericardial cavity
The pericardial sac.
It's not unheard of for Lung Cancer to spread locally to structures nearby such as the heart. It would make it's way in from the outside so getting to the Heart (or Pericardial) Sack first
aspiration of pericardial fluid for diagnostic purposes or treating cardiac tamponade
The pericardial space lies between the pericardium and the epicardium.
Pericardial effusion.
The heart is located in the pericardial and belongs to the cardiovasular system.