Thorac Cardiovasc Surg 2015; 63 - OP76
DOI: 10.1055/s-0035-1544328

The Impact of Ventricular Assist Device Implantation on the Acquired Von Willebrand Syndrome - Comparison of Centrifugal and Axial Design

C. Egger 1, A. Moza 2, A. Goetzenich 2, M. Klein 1, K. Niederau 1, U. Steinseifer 1, R. Autschbach 2
  • 1Helmholtz-Institut RWTH Aachen, Cardiovascular Engineering am Institut für angewandte Medizintechnik, Aachen, Germany
  • 2Klinik für Thorax-, Herz- und Gefäßchirurgie, Uniklinik RWTH Aachen, Aachen, Germany

Objectives: The Acquired von Willebrand Syndrome (AvWS) is accused of causing frequent bleeding complications in patients on ventricular assist device (VAD) support. High shear stress inside the blood pumps is believed to be responsible for shredding of von Willebrand Factor (vWF) high molecular weight multimers (HMWM). In in vitro setting, loss of HMWM occurs within minutes to hours but data from clinical settings lack. We investigated perioperative characteristics of von Willebrand Factor in patients during VAD implantation, comparing a centrifugal device (HeartWare HVAD) to an axial design (Thoratec HeartMate II). As control groups, patients undergoing classical ACVB procedure with or without use of an extracorporal circulation (HLM) were included.

Methods: In the perioperative period, 11 samples were taken from patients undergoing VAD implantation (HVAD n = 5; HeartMate II n = 3), and ACVB procedure on pump (n = 5) or off pump (n = 2) respectively. vWF Activity level (vWF:Ac) and vWF Antigen level (vWF:Ag) were analyzed as a measure for HMWM loss and AvWS, respectively.

Results: Data from both VAD groups showed a momentary increase in vWF:Ac/Ag ratio in first part of surgery with a following decrease (vWF:Ac/Ag < 0.7, AvWS threshold) when VAD was started until observation end (24h post surgery). Data from control groups showed a higher overall vWF:Ac/Ag ratio with a more stable or even increasing trend. vWF:Ag is high in VAD patients over complete observation period, control group showed an increase after surgery. Without reaching statistical significance, the centrifugal device trends to produce the lowest vWF:Ac/Ag ratio (Fig. 1).

Conclusion: Results indicate device dependent AvWS development during VAD implantation (or AvWS is even present before VAD implant). Although the control group patients were supported with a shear inducing device (HLM) during surgery, this seems to have no impact on vWF. Our study is ongoing to increase the number of patients.

Fig. 1.