Reperfusion Injury after Endovascular Stroke Treatment

Stroke is a leading cause of death and disability worldwide. In Austria, around 25.000 people are affected by a stroke each year. In particular, stroke due to the occlusion of large vessels supplying the brain is associated with severe disability or even death. Fortunately, newly- developed treatment approaches have revolutionized the therapy of severe stroke in recent years. This new therapy is called mechanical thrombectomy and works as follows: via puncture of an artery in the groin region, a small catheter is directed to the brain circulation and to the occluded artery under radiological control. Afterwards, the blood clot that is occluding the vessel is removed either by aspiration or by using so called stent retrievers (=mechanical removal of the clot to restore the blood supply to the brain). While this treatment is technically highly effective 90% of vessel occlusions can be recanalized there are also some important complications that need to be considered after mechanical thrombectomy. The most important immediate complication is bleeding into brain, a situation that occurs in every 4th thrombectomy patient and that is related to an increased risk of poor neurological prognosis. The exact mechanisms why some patients develop brain hemorrhage after mechanical thrombectomy are still largely unclear. In first pilot studies, we and other research groups found that simple and complication-free ultrasound examinations of the brain arteries are helpful to predict the risk for brain bleeding after acute stroke treatment as patients who later developed brain hemorrhage had elevated blood flow velocities in the arteries that were just re-opened by mechanical thrombectomy (deleterious elevated blood circulation). In this Austrian multicenter study conducted in Graz, Innsbruck and Salzburg, we now aim to get further insights into the important complication of brain hemorrhage after endovascular stroke treatment. We will use serial ultrasound examinations of the brain arteries to study blood flow velocities and changes as well as novel MRI techniques to investigate brain tissue alterations related to blood flow changes. Furthermore, we intend to identify potential blood markers that might be associated with complications and prognosis after modern stroke treatment. Our overarching goal is to identify patients at risk for stroke complications and poor outcome, and in the long-term, to develop treatment approaches to avoid such complications.