Stroke

Stroke occurs in about 85% of cases due to the occlusion of a cerebral artery or its branches and is then called an “ischemic stroke“. About one-fifth of these cases are caused by an arterial embolus that has developed in the heart: in atrial fibrillation, the atria contract only in an uncoordinated manner.A large part of the blood is therefore not passed on to the ventricles, but circulates in the atrium, can clump together and form an embolus. But a venous thrombus can also be the cause of a stroke.

In particular, if the foramen ovale of the heart is not closed, a thrmobus from the venous blood system without the filter station in the lungs can be washed out into the body’s circulation and thus rapidly into the brain. Most people do not notice this defect in the heart, as it usually causes no to mild symptoms. Another common cause (60%) of ischemic stroke is arterio-arterial embolism.

The patients affected have atherosclerotic changes, e.g. in the aorta or carotid artery, from which components become detached and are carried along as embolus in the arterial system until they get stuck in a cerebral artery. The consequence of the occlusion of the cerebral artery is an acute neurological deficit: those abilities are only possible to a limited extent, if at all, that are controlled by the area of the brain that is supplied by the now occluded blood vessel. Based on the symptoms of failure, conclusions can be drawn about the occluded artery even before examination by CT or MRI. Depending on the region affected, visual disturbances, speech disorders, hemiplegic motor and sensory deficits, swallowing disorders and amnesia (impairment of memory) are possible.

Consequences of an embolism

An embolism closes a vessel, i.e. the part of the vessel behind the embolus is no longer supplied with blood and the associated tissue is no longer supplied with blood. The extent of tissue damage depends on the type of tissue affected, the duration of the vascular occlusion and the extent of the collateral damage (i.e. how well the tissue is supplied with blood by other vessels). In the worst case, the tissue dies.

The consequences of an embolism in the leg or arm can be: compartment syndrome (increased pressure in the limb with damage to surrounding tissue and nerves) and reperfusion trauma with rhabdomyolysis (dissolution of muscle fibers). As a consequence, an acidic metabolic state (metabolic acidosis) and electrolyte disorders occur and there is a risk of acute renal failure. The consequences of a brain embolism or stroke are also severe.

The brain tissue can only survive for four to a maximum of ten minutes without blood supply. This means that in the event of a stroke, brain tissue dies and the abilities that are controlled by the affected brain area are limited or even impossible. Since vital organs are often affected, an embolism can also lead to death if left untreated. It therefore requires rapid diagnosis and treatment. Depending on the cause of the embolism, affected patients must take anticoagulant medication (anticoagulants) for a period of time or for life and/or wear compression stockings.