Haemopericardium, gross specimen. Haemopericardium is a condition in which blood collects in the pericardial sac surrounding the heart, often as a result of a ruptured aorta or heart. The clotted blood in the pericardium is dark blue. The sudden increase in pressure within the sac (cardiac tamponade) interferes with the venous return of blood to the heart from the lungs and the rest of the body. The condition illustrated resulted from a ruptured ventricle wall and would have caused a rapid death.