The function of the pericardium in acute volume overloading may be defined as protection against ventriculo-atrial regurgitation at high filling pressures, limiting transmural pressures and, therefore, protecting against ventricular distension as well as supporting the filling of the ventricles by suction in the systolic contraction. Thus, it may be important to close the open pericardium carefully after open heart surgery. Pericardial drainage should prevent cardiac tamponade.