Acquired von Willebrand syndrome in patients with an axial flow left ventricular assist device.
BACKGROUND
Rotary blood pumps used as left ventricular assist devices (LVADs) allow for long-term support and may become suitable alternatives to heart transplantation. Effects of this technology on the coagulation system are not completely understood, leading to controversial anticoagulation protocols. Thus, we investigated the primary hemostasis in patients with chronic LVAD therapy.


RESULTS
Twenty-six outpatients received axial flow LVAD (HeartMate II; Thoratec) for a median support time of 4.5 months. In a cross-sectional protocol, platelet aggregation in response to ADP and epinephrine, von Willebrand antigen (vWF:AG), and collagen-binding capacity (vWF:CB) were obtained. Von Willebrand factor (vWF) multimer analyses were performed, and patients were screened for bleeding events. This analysis was repeated after removal of the device for transplantation or recovery (n=12) and after a median of 15.5 months in ongoing patients (n=11). In all patients on devices, severe impairment of platelet aggregation as well as a loss of large vWF multimers were found. In 10 patients, a decreased vWF:CB/vWF:AG ratio was observed. Bleeding episodes occurred with an incidence of 0.17 per patient-year. After removal of the device, normal patterns of platelet aggregation, multimer analysis, and vWF:CB/vWF:AG ratio were recorded. In the second analysis of ongoing patients, impairment of platelet aggregation and loss of large vWF multimers were verified.


CONCLUSIONS
A diagnosis of von Willebrand syndrome type 2 was established in all patients after LVAD implantation, and bleeding events confirmed this finding. Reversibility of this condition was found after removal of the device.
Meyer
Anna L
AL
Department of Cardiothoracic, Transplant and Vascular Surgery, Hannover Medical School, Carl-Neuberg-Strasse 1, Hannover, Germany.
Malehsa
Doris
D
Bara
Christoph
C
Budde
Ulrich
U
Slaughter
Mark S
MS
Haverich
Axel
A
Strueber
Martin
M
D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D003094:Collagen / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D016027:Heart Transplantation / Q000706:statistics & numerical data; D006353:Heart-Assist Devices / Q000009:adverse effects*; D006470:Hemorrhage / Q000453:epidemiology / Q000209:etiology; D006487:Hemostasis; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation; D012086:Reoperation; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000097:blood / Q000601:surgery*; D055815:Young Adult; D056728:von Willebrand Disease, Type 2 / Q000150:complications / Q000209:etiology*; D014841:von Willebrand Factor / Q000737:chemistry / Q000378:metabolism
D014841:von Willebrand Factor; D003094:Collagen