Related Experiment Video
Updated: Feb 9, 2026

Investigating von Willebrand Factor Pathophysiology Using a Flow Chamber Model of von Willebrand Factor-platelet String Formation
Published on: August 14, 2017
Speed Reduction Does Not Restore High Molecular Weight von Willebrand Multimers During HeartMate II Support: An In
Omar Saeed1, Sabarivinoth Rangasamy1, Morayma Reyes Gil2
1From the Division of Cardiology, Department of Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York.
Abstract:
Acquired von Willebrand Syndrome (AVWS) in patients undergoing continuous-flow left ventricular assist device support is due to the loss of von Willebrand factor (vWF) high molecular weight multimers (HMWMs) by shear-mediated mechanisms. We investigated whether reducing speed in vivo would mitigate the shear effect. In outpatients (n = 6) with a HeartMate II, pump speed was decreased to 8,000 rpm for 6 hours. At baseline (9,140 ± 189 rpm), patients had an AVWS as evidenced by low vWF activity:antigen ratios (0.58 ± 0.13, normal >0.7) and reduced HMWMs. After 6 hours, there was no significant change in either the vWF activity:antigen ratio or the HMWMs. Decreasing pump speed does not ameliorate AVWS.
Related Concept Videos
Distribution of Molecular Speeds
Polymers: Defining Molecular Weight
The number average molecular weight (Mn) is the summation of the number...
Polymers: Molecular Weight Distribution
Molecular Weight of Step-Growth Polymers
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
Anticoagulant Drugs: Low-Molecular-Weight Heparins
Restorative Care

