Ruptured heart. Gross specimen of a heart that has ruptured in the parietal region (dark blood clots, lower centre, and red region, centre). The heart has also suffered tissue death (infarction), which causes the pain of a heart attack. The heart sac (pericardium) has an inner serous layer, the outermost layer of which is the parietal layer. Such ruptures can occur as a result of a heart attack. In a heart attack, the blood supply from the coronary arteries to the heart muscle is blocked. This cuts off the oxygen supply and the tissue dies.