What causes stroke?
An ischaemic stroke occurs when a blood clot obstructs blood flow to a portion of the brain. The blocked vessel is already narrowed by years of plaque build-up due to atherosclerosis (narrowing of the arteries). The clot that serves as the final plug may be either a stationary blood clot created on the spot (thrombus), or an embolus composed of blood, plaque or some other substance that formed elsewhere and travelled to the site. For example, in the heart condition called atrial fibrillation the small pumping chambers of the heart (atria) do not contract in a coordinated way with the heartbeat. This can encourage tiny clots to form in the blood, which are then sent into the bloodstream by the main pumping chambers (ventricles). If one of these small clots lodges in a brain artery an embolic stroke can result.
Blood clots. Stroke-triggering blood clots may be produced when blood flow is sluggish. After a heart attack, for example, clots may form on the damaged heart wall because of slower blood flow there.
No comments:
Post a Comment