Willebrand Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Willebrand and links to relevant pages within the course.
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| Which of the following blood components will provide the best source of fibrinogen for a patient with hypofibrinogenemia: | View Page |
| Hemophilia A, hemophilia B, and Von Willebrand's disease together constitute approximately what percentage of all hereditary coagulation disorders: | View Page |
| Platelet adhesion involves the absorption of this factor between receptors on the exposed subendothelial tissue, and by receptors on the platelets themselves? | View Page |
| The product administered to treat Von Willebrands Disease is? | View Page |
| Primary Hemostasis – Platelet Kinetics Kinetic Processes Specific to Platelets. Adhesion – When platelets adhere to exposed collagen, they take on a characteristic “spiny” shape. Their inherent stickiness, and the aforementioned spiny shape serve to compliment each other during this process. Von Willebrands Factor (vWF) is absorbed by surface receptors on both the platelet and exposed subendothelial tissue, thereby linking the platelets to the tissue. Release – This process occurs prior to aggregation. Platelets dump the contents of their granules (ADP, Serotonin, & Calcium), which aids the upcoming aggregation process by acting as a chemical signal. Aggregation – Platelets physically bind to each other, not just to the exposed subendothelial walls and collagen of the breached vessel. Platelet aggregation requires sufficient chemical signal stimulation. Stabilization (technically part of secondary hemostasis as fibrin is a product of secondary hemostasis)– This process strengthens the platelet plug with the addition of interwoven fibrin strands, ultimately producing a fibrin clot. The durable fibrin clot is the ultimate goal of hemostatic processes. | View Page |
| Tests of Hemostatic Function - Platelet Function Assay A platelet function assay (PFA) is a screening test for the evaluation of platelets/primary hemostasis. Common clinical applications include the following: Preoperative evaluation of platelet function Determining the presence of drug-induced platelet dysfunction Determining platelet functionality in high-risk pregnancy Evaluation of patients with suspected inherited or acquired platelet disorders such as von Willebrand disease Evaluation of a bleeding patientA PFA instrument is able to differentiate between drug-induced platelet defects and other platelet defects. PFA tests are superior to the bleeding time test. The bleeding time is often not reproducible and, in spite of attempts at standardization, remains prone to variations in test results between persons performing the test. It is also relatively insensitive to platelet function. The bleeding time cannot be used to identify patients who may have recently ingested aspirin or non-steroidal anti-inflammatory drugs or patients who may have a platelet defect attributable to these drugs. The bleeding time is used to assess platelet function, but may be affected by platelet quantity. NOTE: Aspirin, and some other drugs, may falsely prolong bleeding times. Patients must be asked about aspirin use, and be aspirin free for 7-10 days prior to testing, for valid results. | View Page |
| Coagulation Disorders - Inherited Von Willebrands Disease is a platelet disorder. This disorder is characterized by a functional defect in Von Willebrands factor (vWF) itself. This disease often clinically manifests with a concurrent deficiency of factor VIII, but will present with a normal platelet count. As far as genetics and inheritance, both men and women are affected equally. Von Willebrands factor is essential for platelet binding, therefore, a defect in vWF causes impaired platelet adhesion and aggregation. The treatment of Von Willebrands Disease involves the administration cryoprecipitate, as it is rich in vWF. | View Page |
| Which of the following statements regarding coagulation disorders is incorrect? | View Page |