Heart ultrasound scan. This is an image of the heart obtained using ultrasound, also known as an echocardiogram. The dark areas represent the chambers of the heart and the yellow areas show blood flow. This technique is used to diagnose structural and functional defects including congenital heart disease and cardiomyopathy.It uses the differential reflection of high frequency sounds waves from each region of the heart to compile an echo map of its structure. The line along the bottom of the scan is an electro- cardiogram trace of the heartbeat.