Due to inclusion difficulties following the evolution of surgical indications, which were clearly restricted, making patient inclusion too complex.

Implanting a ventricular assist device (VAD) is a promising therapy for end-stage cardiac failure. However, the implantation of these devices is associated with a high risk of severe hemorrhages and massive blood product transfusion in the first 48 hours following the implantation. The primary purpose of this study is to assess the functionality of the von Willebrand Factor (vWF) which is essential for hemostasis. The hypothesis is that the high shear stress generated by these VAD expose ADAMTS13 cleaving site on the vWF. This result in a loss of high molecular weight vWF and an acquired von Willebrand syndrome.

The secondary purpose of the protocol is to assess platelet function after the implantation of VAD. Indeed, platelet function might be affected shortly after the implantation of the device.

Inclusion Criteria:

• Age over 18 years old
• Who gave his consent to the study
• With an end-stage heart-failure
• Under surgery for a ventricular assist device implantation
• Scheduled or in emergency

Exclusion Criteria:

• Preoperative anemia less than 7 g/dL
• Subject under the protection of justice
• Subject under guardianship or curatorship
• Pregnancy
• Breastfeeding

Patient with end-stage heart failure (acute or chronic) under surgery for implantation of a ventricular assist device.