Carotid Doppler Ultrasound is a high-frequency echocardiography used to examine the carotid arteries (5-6 mm large arteries located on both sides of the neck, left and right) to see the blood flow up to the brain and if there is plaque or fat in the blood vessels, by measuring the thickness of the artery walls and the velocity of blood flow in the blood vessels. If the carotid artery walls are thickening due to a build-up of plaque, which narrows the diphtheria blood vessels, or have blood clots from a blood vessel in this area that have escaped to the peripheral artery, it will cause poor/no blood supply to the brain, cerebral ischemia, and subsequent paralysis (stroke).