Pericarditis Pericarditis is inflammation of the pericardium, the thin sac (membrane) that surrounds the heart. Rheumatic Heart Disease Rheumatic heart disease is a condition in which the heart valves have been permanently damaged by rheumatic fever. Cardiac Sarcoma Cardiac sarcoma is a rare type of cancerous tumor that occurs in the heart. Congenital Heart Defects When the heart or blood vessels near the heart do not develop normally before birth, a condition called congenital heart defect occurs. A Serious Look at Fainting Fainting is a loss of consciousness, falling down or needing to lie down, followed by spontaneous recovery. Fainting by itself is not a problem, but it could be a sign of a serious health condition. The Lowdown on Low Blood Pressure Doctors often consider chronically low blood pressure too low only if it drops suddenly or causes noticeable symptoms.