Pathophysiology Ischemic Stroke

In ischemic stroke, there is an interruption of the blood supply to an area of the brain either due to thrombus formation or an embolism. Loss of cerebral blood flow results in tissue hypoperfusion, tissue hypoxia, and cell death. Tipid deposits in the vessel wall cause turbulent blood flow and lead to vessel injury, exposing vessel collagen to blood. This vessel injury initiates the platelet aggregation process due to the exposed subendothelium. Platelets release adenosine diphosphate (ADP), which causes platelet aggregation and consolidation of the platelet plug. Thromboxane A2 is released, contributing to platelet aggregation and vasoconstriction. The vessel injury also activates the coagulation cascade, which leads to thrombin production. Thrombin converts fibrinogen to fibrin, leading to clot formation as fibrin molecules, platelets, and blood cells aggregate. Refer to Figures 7-3, 10-3, and 10-4 for a depiction of these processes.

After the initial event, secondary events occur at the cellular level that contribute to cell death. Regardless of the initiating event, the cellular processes that follow may be similar. Excitatory amino acids such as glutamate accumulate within the cells, causing intracellular calcium accumulation. Inflammation occurs and oxygen free radicals are formed resulting in the common pathway of cell death.

There is often a core of ischemia containing unsalvageable brain cells. Surrounding this core is an area termed the ischemic penumbra. In this area cells are still salvageable; however, this is a time-sensitive endeavor. Without restoration of adequate perfusion, cell death continues throughout a larger area of the brain ultimately leading to neurologic deficits. No agents have been shown to be effective at providing neuroprotection at this time.

Your Heart and Nutrition

Your Heart and Nutrition

Prevention is better than a cure. Learn how to cherish your heart by taking the necessary means to keep it pumping healthily and steadily through your life.

Get My Free Ebook

Post a comment