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Hemostatic evaluation of Sarns/3M-VAD implantation in calves
D L Amrani1, C Christensen, L Hauerwas
1Department of Health Sciences, University of Wisconsin-Milwaukee.
Insights
Ventricular assist device (VAD) implantation in calves showed limited value of standard coagulation tests for predicting thrombotic complications. Platelet reactivity markers, including platelet count and aggregation, effectively indicated hemostatic system activation post-VAD implantation.
Area of Science:
- Biomedical Engineering
- Cardiovascular Surgery
- Hematology
Background:
- Ventricular assist devices (VADs) are crucial for managing heart failure.
- Thrombotic complications remain a significant risk following VAD implantation.
- Predictive markers for hemostatic system activation are needed to mitigate VAD-related thrombosis.
Purpose of the Study:
- To evaluate thrombotic complication risks associated with Sarns/3M-VAD implantation in a preclinical model.
- To assess the predictive value of various coagulation and platelet function tests for hemostatic system activation.
Main Methods:
- Implantation of Sarns/3M-VAD in four calves.
- Monitoring of coagulation screening tests (PT, PTT, TT), fibrinogen, antithrombin III activity.
- Assessment of platelet counts, adenosine diphosphate (ADP)- and collagen-induced platelet aggregation, and thromboxane (TXB2) levels.
- Utilized a bovine D-dimer assay and Western blot to detect fibrin formation and dissolution.
Main Results:
- Standard coagulation tests showed limited predictive value for hemostatic activation.
- Platelet counts, ADP- and collagen-induced platelet aggregation, and TXB2 levels correlated with platelet reactivity changes.
- Platelet counts and aggregation remained elevated for 25 days post-implantation.
- A small but significant increase in circulating bovine D-dimer indicated localized fibrin formation and dissolution.
Conclusions:
- Platelet function tests are superior to standard coagulation assays in predicting hemostatic system activation after VAD implantation.
- VAD implantation in calves leads to sustained alterations in platelet reactivity and localized fibrin formation.
- Further research is warranted to optimize VAD design and anticoagulation strategies to minimize thrombotic risks.
Abstract:
The authors evaluated the potential for thrombotic complications arising from implantation of a ventricular assist device (Sarns/3M-VAD) in four calves. Coagulation screening tests (prothrombin time [PT], partial thromboplastin time [PTT], thrombin time [TT]), fibrinogen levels, and antithrombin III functional activity were found to be of little value as predictors of the degree of activation of the hemostatic system. However, platelet counts, adenosine diphosphate (ADP)- and collagen-induced platelet aggregation, and thromboxane (TXB2) levels were good indicators of changes in platelet reactivity. Platelet counts (initial value 6 x 10(5) rose, and were associated with increased rate and extent of ADP- and collagen-induced platelet aggregation, which remained elevated during the entire 25 day postimplantation period. The first 5 days postimplantation revealed a typical acute inflammatory response, with increased platelet levels, but with TXB2 levels significantly decreased during this period. A monoclonal antibody based bovine D-dimer assay and Western blot studies indicated a small but significant increase in circulating bovine D-dimer, indicating localized fibrin formation and its dissolution.