Sometimes, in special circumstances, clots form within the cardiac chambers themselves, and can break apart and be carried either to the brain or to the legs. This is called an embolism. Most strokes appear to be the result of clots carried in the carotid arteries, two large blood vessels in the neck that supply blood from the heart to the brain. In my opinion, your father's massive stroke was not due to his being moved from bed to wheelchair. Nonetheless, such an event is in the realm of possibility.
Hemorrhagic strokes occur primarily in patients with poorly controlled hypertension.
This disease places enormous strain on the arterial system because the outward pressure exerted on the arteries is much higher than normal. With time, small arteries in the brain stretch to their maximum and burst from the excessive pressure, flooding healthy brain tissue. The dual nature of strokes was recently brought home to me. My patient was in danger of having a stroke because of diseased and narrowed carotid arteries. He had had several mini-strokes and tests confirmed that his right carotid artery was 90 percent blocked.