Heart murmur is an abnormal sound in a person’s heartbeat. An organic murmur is a symptom of heart disease. It is produced by the blood flowing through defective heart valves or across defects between chambers of the heart. A diseased heart valve may not close tightly or open completely when the heart contracts, and the forceful passage of blood around the valve causes a murmur. Causes of organic murmur include (1) rheumatic fever, (2) heart deformities present at birth, and (3) arteriosclerosis (hardening of the arteries). A functional murmur, also called an innocent murmur, occurs in the absence of heart disease. It may appear after a person exercises strenuously.