Patients with VAD implants develop varying severities of AVWS

The findings of a 12 patient study recently published in Thrombosis and Haemostasis by University Medical Center Freiburg documented that patients implanted with a ventricular assist device (VAD) experienced a rapid onset of acquired von Willebrand syndrome (AVWS), while patients implanted with the SynCardia temporary Total Artificial Heart did not. The lead author of the study was Dr. Claudia Heilmann, Head of the Research Department for the Department of Heart and Vascular Surgery at University Medical Center Freiburg.

“While patients with different types of VADs developed varying severities of AVWS, none of the SynCardia Total Artificial Heart patients developed it”

"While patients with different types of VADs developed varying severities of AVWS, none of the SynCardia Total Artificial Heart patients developed it," said Prof. Dr. Friedhelm Beyersdorf, Director of Heart and Vascular Surgery at University Medical Center Freiburg. "The results of our study suggest that shear stress associated with exposure of blood to VAD cannulas and tubes may contribute to the development of AVWS. In contrast, the Total Artificial Heart connects directly to the remaining left and right atria, aorta and pulmonary artery, eliminating the need for cannulas and tubes."

The study evaluated 12 patients who underwent implantation of a VAD or the SynCardia Total Artificial Heart between June 2006 and March 2009. Nine patients received VADs; two received HeartMate II left ventricular assist devices (LVAD), five received two Thoratec PVADs (Paracorporeal Ventricular Assist Devices) for biventricular support and two received the VentrAssist LVAD. Three patients received the SynCardia Total Artificial Heart.

Within two weeks of implantation, eight of the nine VAD patients had developed AVWS, and over the course of the study, all nine. AVWS was not observed at any point in time with the Total Artificial Heart patients. Haemolysis was most pronounced in BiVAD patients, less severe with the HeartMate II and mild in patients with the VentrAssist.

"Acquired von Willebrand Factor deficiency, a hemorrhagic risk factor, has entered into the lexicon and clinical practice of mechanical circulatory support over the past couple of years," said Paul E. Nolan, Jr., PharmD, Professor of Pharmacy Practice & Science at the University of Arizona. "The group from University Medical Center in Freiburg should be congratulated for performing this prospective study. The absence of acquired von Willebrand Factor deficiency in Total Artificial Heart patients should be encouraging to clinicians and their patients. However, what is unknown at this point is whether acquired von Willebrand Factor deficiency occurs with patients implanted with the Total Artificial Heart for durations exceeding one year."