A heart murmur is caused by a defect in the heart valve, C. A heart murmur is a sound that can be heard through a stethoscope. It is not a structural problem with the heart but a physical finding. These murmurs occurs when there is turbulent blood flow in the heart. Most common cause of heart murmurs are due to the abnormal functioning of the valve of the heart. these valves may have stenosis or regurgitation.
