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FH Kohanna, MH Smith and EW Salzman
Reports of circulating platelet aggregates (ie, microemboli) in
thromboembolism and other vascular disorders are based on a method (Wu and
Hoak , 1974) in which venous blood is collected via scalp vein needle and
tubing into either formaldehyde, which fixes aggregates, or EDTA, which
disperses them. The ratio of platelet counts in platelet- rich plasma (PRP)
from the two blood samples after centrifugation is interpreted as a measure
of platelet aggregates in the circulation in vivo. We compared this
standard Wu and Hoak technique with a modified one, in which blood was
drawn directly into a syringe, and with a third method that avoided
centrifugation by counting single platelets in whole blood. Both modified
techniques could detect aggregates generated in vitro with adenosine
diphosphate (ADP). In 12 normal subjects, the three methods were
equivalent, but in 37 patients with thromboembolic disorders, the standard
Wu and Hoak method gave a lower ratio than the other methods. Similar
results were found in a subset of eight patients with myocardial
infarction. Heparin treatment of patients did not influence the results.
The data suggest that formation of platelet aggregates occurred during
venipuncture. Platelets may be hyperactive in patients with thromboembolic
disease and may form aggregates in vitro during collection, but the concept
of chronic microembolism in such patients should be reassessed.
This article has been cited by other articles:
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| Copyright © 1984 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
