HM06 - Heparin Induced VCM Tracing Changes Compared to Aptt and Anti-xa Activity in ex-vivo Canine Blood

Background – Heparin is a widely utilized treatment for thromboprophylaxis.  Currently, no reliable cage-side option is available to monitor heparin therapy.  As many hypercoagulable disease states are dynamic, real-time monitoring ability is crucial. The VCM offers a novel potential monitoring option. 

Hypothesis/Objectives – To evaluate the impact of unfractionated heparin (UFH) on canine whole blood VCM tracings, and assess the relationship between VCM variables, aPTT, and anti-Xa levels. 

Animals – Six healthy adult dogs. 

Methods – Prospective benchtop study.  Untreated whole blood samples were collected from each dog into UFH-free syringes and pre-heparinized syringes at three ex-vivo UFH doses (100U/kg, 250U/kg, and 600U/kg equivalent concentrations) for analysis.  Correlations aPTT, anti-Xa levels, and viscoelastic (VCM) variables were assessed at each UFH dose.  

Results – CT, CFT, ɑ angle, ɑ10, ɑ20, and MCF changed significantly (p<0.05) as UFH dose increased. However, there was no significant correlation between VCM variable values and either aPTT or anti-Xa levels. 

Conclusions/clinical importance – This is the first known attempt to utilize the VCM to monitor the effect of UFH on canine blood.  Statistically significant changes were appreciated between each UFH dose for multiple VCM variables.  While anti-Xa levels and VCM variables were not found to have a statistically significant correlation, visible changes in the tracings suggest a relationship between CT, CFT, ɑ angle, MCF, and anti-Xa levels.  In-vivo research in a larger population is warranted to solidify the clinical role of the VCM in cageside monitoring of heparin therapy.