Valve thrombogenicity

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Johanna Clauser

Chief Scientist Research & Validation

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+49 241 80 89356

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  In vitro test bench of the CVE THIA 3 Copyright: © CVE In vitro test bench of the CVE THIA 3

Background

The number of patients with cardiovascular diseases increases continuously in Germany. Thus, the number of aortic valve surgeries increases as well. If a surgery is necessary, the aortic valve is either reconstructed or replaced by an artificial one. For the replacement, different valve types depending e.g. on the patient age are available in the clinic. The surgical valves can be divided in mechanical and biological prostheses. In contrast to biological ones, mechanical prostheses have a longer durability but require a lifelong anticoagulation therapy due to the higher risk of thrombus formation. However, thrombus formation on biological valves is a recently discussed topic, since new imaging techniques allowed for thrombus detection on biological valves as well.

Objective

The aim of this project is to verify this new clinical findings under reproducible physiological conditions. Therefore, a biological prosthesis (Medtronic Hancock II), which is commonly used in the clinic, is investigated in an in‑vitro‑study. Due to the high thrombogenicity of mechanical prostheses, a mechanical valve is used as reference for this in‑vitro‑study. The St. Jude Medical is considered the gold standard in the clinic and is therefore used in this study. By means of a benchmark between the two valves, the thrombogenicity of the biological valve prostheses is evaluated. Additionally, the study gives information about the origin, size and amount of thrombotic depositions.

Methods

The CVE owns an in‑vitro‑test bench (THIA 3), which allows for the evaluation of the thrombogenicity of artificial prostheses. The test bench reproduces the physiological conditions of the left ventricle and the test fluid is porcine blood. During the test procedure, the hydrodynamic conditions such as pressure and flow are controlled and blood parameters like platelet count and Rotem are measured. After the end of the test, the thrombotic material is fixed on the valves and the weight difference of the valve before and after the test is noted. Besides the amount of thrombotic material, the origin of thrombi is of further interest and investigated under the microscope. For further analyses of the thrombotic material, histological examinations are undertaken externally. The histological examinations reveal the detection of smallest clots and its elements like proteins and cell type.