Colour echocardiogram (colour flow doppler map) of the human heart showing aortic regurgitation, represented by the orange area at bottom left of image. Colour flow mapping is a complex variation of ultrasound cardiography that is used to display the flow of blood through the heart. Aortic regurgitation is a reflux (a reverse flow) of blood from the aorta back into the left ventricle of the heart during contraction. The condition results from a defective aortic valve, caused by a previous acute rheumatic fever or syphilis. Symptoms include breathlessness, angina & heart enlargement; a severely damaged valve may necessitate replacement with an artificial valve.