A carotid Doppler is an imaging test used to help determine coronary artery disease. It uses ultrasound to examine the carotid arteries in the next, which can show a narrowing or blockage in the arteries due to a build up of plaque. The test itself is straightforward. You will lie flat on a table, with your head slightly turned away from the side being examined. Gel is applied to the ultrasound probe, which is placed on one side of your neck. In order to obtain good quality images, some pressure will be applied with the probe. The probe will use high frequency sound waves to create images of the arteries and Doppler technology is then used to analyse the speed and direction of blood flow. During the test you will hear sounds due to the Doppler. The test will take 15-30 minutes and there are no side effects.