In addition the pulses of the dorsal foot artery are palpated. Height and weight are assessed as well as medication intake, especially dose and type of anticoagulation therapy. Laboratory testing will include C-reactive protein and D-Dimer test at visit 1, 2 and 3, as well as thrombophilia screening (anti-thrombin, anti protein C resistance, protein C, protein S, Lupus anticoagulans, prothrombinfragment 1 and 2, factor II mutation G 202 10 A)