1.2.1. Mechanical thrombectomy systems - The first generation with Merci (Merci Retrieval System) device of Concentric Medical and Penumbra system (Penumbra system) of Penumbra Inc - The second generation has stent Solitaire (Solitaire FR stentriever) of Covidien, stent Trevo (Trevo ProVue stentriever) of the Stryker company and A Direct Aspiration First Pass Technique (ADAPT) of Penumbra Inc 1.2.2.