Impact of loss of high-molecular-weight von Willebrand factor multimers on blood loss after aortic valve replacement.
BACKGROUND
Severe aortic stenosis is associated with loss of the largest von Willebrand factor (vWF) multimers, which could affect primary haemostasis. We hypothesized that the altered multimer structure with the loss of the largest multimers increases postoperative bleeding in patients undergoing aortic valve replacement.


METHODS
We prospectively included 60 subjects with severe aortic stenosis. Before and after aortic valve replacement, vWF antigen, activity, and multimer structure were determined and platelet function was measured by impedance aggregometry. Blood loss from mediastinal drainage and the use of blood and haemostatic products were evaluated perioperatively.


RESULTS
Before operation, the altered multimer structure was present in 48 subjects (80%). Baseline characteristics and laboratory data were similar in all subjects. The median blood loss after 6 h was 250 (105-400) and 145 (85-240) ml in the groups with the altered and normal multimer structures, respectively (P=0.182). After 24 h, the cumulative loss was 495 (270-650) and 375 (310-600) ml in the groups with the altered and normal multimer structures, respectively (P=0.713). Multivariable analysis revealed no significant influence of multimer structure and platelet function on bleeding volumes after 6 and 24 h. After 24 h, there was no obvious difference in vWF antigen, activity, and multimer structure in subjects with and without the altered multimer structure before operation or in subjects with and without perioperative plasma transfusion.


CONCLUSIONS
The altered vWF multimer structure before operation was not associated with increased bleeding after aortic valve replacement. Our findings might be explained by perioperative release of vWF and rapid recovery of the largest vWF multimers.
Department of Anaesthesia and Intensive Care Medicine, University Hospital Basel, Basel, Switzerland. dabolliger@uhbs.ch
D
D
Bolliger
S
S
Dell-Kuster
M D
MD
Seeberger
K A
KA
Tanaka
M
M
Gregor
U
U
Zenklusen
D A
DA
Tsakiris
M
M
Filipovic
D000368:Aged; D000369:Aged, 80 and over; D001024:Aortic Valve Stenosis / Q000097:blood / Q000601:surgery*; D015415:Biomarkers / Q000097:blood; D001800:Blood Specimen Collection / Q000379:methods; D001803:Blood Transfusion; D005260:Female; D005500:Follow-Up Studies; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008970:Molecular Weight; D010974:Platelet Aggregation / Q000502:physiology; D019106:Postoperative Hemorrhage / Q000097:blood* / Q000209:etiology; D011446:Prospective Studies; D055503:Protein Multimerization; D014841:von Willebrand Factor / Q000378:metabolism*
D015415:Biomarkers; D014841:von Willebrand Factor