The pericardial space is located between the epicardium (also known as the visceral pericardium) and the parietal pericardium. A tear of a blood vessel immediately outside of the hea will cause bleeding into the pericardial space. This accumulation of blood in the pericardial space causes increased pressure on the hea, which restricts filling of the hea during diastole (cardiac tamponade). This reduced filling results in reduced cardiac output and reduced blood pressure. The region between the fibrous pericardium and the parietal pleura is outside of the pericardial space. It is pa of the mediastinum and it is in this region in which structures such as the vagus nerve and the phrenic nerve are found. The epicardium is fused to the myocardium and is the outer layer of the hea wall. There is no space between the epicardium and the myocardium. The parietal pericardium and the fibrous pericardium are fused into a single layer that forms the outer wall of the pericardial space. There is no space between the parietal pericardium and the fibrous pericardium.