Pericardial effusion can cause chest pain because patients with pericardial effusion have limited cardiac diastolic expansion, resulting in a restricted blood volume during the cardiac diastolic phase. This ultimately causes reduced cardiac pumping, leading to symptoms of ischemia and hypoxia, such as chest tightness or chest pain. Furthermore, as the amount of pericardial effusion decreases, for example from moderate or large volumes to a small amount, chest pain symptoms can also occur. This is because when the volume of pericardial effusion significantly reduces, there can often be friction between the visceral and parietal layers of the pericardium, thereby triggering chest pain. This condition is often accompanied by a pericardial friction rub, which can be felt by touching the precordial area.