Stroke due to thrombus. Illustration of an abnormal blood clot (thrombus) causing a stroke (cerebrovascular accident, CVA). The blood clot, which has detached from somewhere between the lungs and the heart, is shown entering the heart and then travelling to the brain. If the blood clot lodges in a brain artery, then the oxygenated blood supply will be interrupted (occluded). This will cause a stroke, where the brain is damaged due to hypoxia (lack of oxygen). This is known as a thrombotic stroke. Common causes are high blood pressure and arterial disease.