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CLINICAL RESEARCH: HEART FAILURE

Severely Impaired von Willebrand Factor-Dependent Platelet Aggregation in Patients With a Continuous-Flow Left Ventricular Assist Device (HeartMate II)

Jolanta Klovaite, MD^_*, Finn Gustafsson, MD, PhD, Svend A. Mortensen, MD, DMSc, Kåre Sander, MD, DMSc and Lars B. Nielsen, MD, PhD, DMSc^_*,,_*

^_* Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
Department of Cardiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
Department of Thoracic Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark

Manuscript received November 11, 2008; revised manuscript received February 6, 2009, accepted February 10, 2009.

^_* Reprint requests and correspondence: Dr. Lars B. Nielsen, Department of Clinical Biochemistry, KB3011, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark (Email: larsbo{at}rh.dk).

Objectives: This study investigated the influence of the mechanical blood pump HeartMate II (HMII) (Thoratec Corporation, Pleasanton, California) on blood coagulation and platelet function.

Background: HMII is an implantable left ventricular assist device used for the treatment of heart failure. Patients treated with HMII have increased bleeding tendencies.

Methods: We measured agonist-induced platelet aggregation in 16 patients on HMII support.

Results: The von Willebrand factor (vWF)-dependent ristocetin-induced platelet aggregation was impaired in 11 of the 16 patients, of which 12 had experienced at least 1 minor or major bleeding episode. The impaired ristocetin-induced platelet aggregation was associated both with decreased specific activity of plasma vWF, presumably due to lack of high molecular weight vWF multimers, as well as with attenuated function of the platelets themselves.

Conclusions: The results imply that HMII treatment is associated with impaired platelet aggregation, which may contribute to an increased tendency to bleed.

Key Words: heart-assist device • hemorrhage • platelets

Abbreviations and Acronyms   ADAMTS-13 = a disintegrin and metalloproteinase with a thrombospondin type 1 motif, 13   ADP = adenosine diphosphate   CHF = congestive heart failure   HMII = HeartMate II   HTx = heart transplantation   INR = international normalized ratio   LVAD = left ventricular assist device   PPP = platelet-poor plasma   PRP = platelet-rich plasma   vWF = von Willebrand factor   vWF:Ag = von Willebrand factor antigen   vWF:RCo = von Willebrand factor ristocetin-cofactor activity

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J. Am. Coll. Cardiol. 2009 53: A24. [Full Text] [PDF]