A cardiac tamponade occurs when blood builds up in the pericardium and puts pressure on the heart. the pressure can restrict the heart from filling properly and can cause a severe decrease in blood pressure for the patient. A surgeon has to cut a pericardial window to relieve the pressure. Through which layer of pericardium would the surgeon have to cut first? a. Visceral pericardium b. Epicardium c. Serous pericardium d. Fibrous pericardium