Vascular Disorders and Thrombosis Quiz

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Questions and Answers

What is a common consequence of disseminated intravascular coagulation (DIC)?

Increased platelet count

Widespread vasodilation

Hypercoagulation

Bleeding (correct)

Which condition is NOT typically associated with Heparin Induced Thrombocytopenia with Thrombosis?

Increased fibrinogen levels (correct)

Thrombosis after 5 days of heparin use

30% fall in platelet count

Clinical diagnosis of thrombocytopenia

What triggers the immune response in Vaccine Induced Prothrombotic Immune Thrombocytopenia?

Direct viral infection of platelets

Uncontrolled platelet production

Platelet activation predominately by PF4 (correct)

Viral antibodies inhibiting hemostasis

What is the estimated incidence of Vaccine Induced Prothrombotic Immune Thrombocytopenia after receiving the Astra Zeneca COVID vaccine?

1 in 100,000 Signup and view all the answers

What is one of the hallmarks of microvascular thrombosis in DIC?

Consumption of clotting factors Signup and view all the answers

What is the normal range for platelet count in the human body?

150-400 x 10^9/l Signup and view all the answers

Which components are part of the haemostatic system?

Platelets, vascular endothelium, procoagulant proteins, and natural anticoagulants Signup and view all the answers

What is the primary function of platelets during haemostasis?

Clot formation and repair of vessel walls Signup and view all the answers

What laboratory test is commonly associated with evaluating platelet function?

Platelet aggregation tests Signup and view all the answers

A patient with prolonged APTT may indicate a deficiency in which coagulation factor?

Factor VIII Signup and view all the answers

Which of the following conditions is associated with increased thrombotic activity?

Antithrombin deficiency Signup and view all the answers

What role does Thrombin play in the coagulation cascade?

It activates proteins and platelets Signup and view all the answers

Which of the following is NOT a known risk factor for Venous Thromboembolism (VTE)?

Regular exercise Signup and view all the answers

What is a common laboratory finding in Disseminated Intravascular Coagulation (DIC)?

Prolonged PT and APTT Signup and view all the answers

The function of Von Willebrand factor is primarily to:

Facilitate platelet aggregation and protect Factor VIII Signup and view all the answers

Which of the following factors is synthesized in the liver and involved in the intrinsic pathway of coagulation?

Factor IX Signup and view all the answers

What is the impact of aspirin on platelet function?

Inhibits platelet aggregation Signup and view all the answers

Which condition is characterized by a deficiency in intrinsic pathway factors and exhibits isolated APTT prolongation?

Hemophilia A Signup and view all the answers

Deep vein thrombosis (DVT) primarily involves which type of thrombus?

Venous thrombus Signup and view all the answers

Study Notes

Haemostasis and Thrombosis

Haemostasis is the process of clot formation and clot breakdown.
Haemorrhage means bleeding.
Thrombosis means clotting.
Clot formation and breakdown are a balanced process in the body.
Any imbalance can lead to haemorrhage or thrombosis, both common in medical practice.

Objectives

Describe components of the haemostatic system
Understand basic laboratory principles
Identify common bleeding and thrombotic disorders
Understand principles of treatment

Introduction

Clinical case studies are used to illustrate haemostatic system principles
Includes components of the haemostatic system
Includes testing principles
Includes platelets and clotting factors
Includes bleeding and clotting disorders

Clinical Case Study

A 74-year-old woman, 15 days after receiving the Astra Zeneca COVID-19 vaccine, experienced pain and swelling in her left lower limb.
Doppler ultrasound suggested a femoral deep vein thrombus.
Her platelet count was 54 x 10⁹/L (normal < 0.4).
Her D-dimer level was 5.0 ng/mL (normal < 0.4).

Platelets

Platelets are produced in the bone marrow by megakaryocytes.
Normal platelet count is 150-400 x 10⁹/L.
A count below 10 x 10⁹/L can lead to spontaneous bleeding.
Platelets circulate for about 10 days.
Platelets are crucial in primary hemostasis, initially closing defects in vessel walls by forming platelet plugs.
Platelets contain procoagulant and anticoagulant factors within granules.
Platelets activate clotting factors that bind to their membrane surfaces.

Platelet Functions

Adhesion: Platelets adhere to exposed subendothelium.
Release: Platelets release substances like ADP and thromboxane A2, aiding aggregation and activation.
Aggregation: Platelets aggregate (clump together) at the site of injury.
Activation of clotting factors: Platelets activate clotting factors to strengthen the clot.

Platelet Adhesion

Platelets bind to exposed subendothelium via specific receptors (such as GP1b/IX/V and GPVI).
Von Willebrand factor (vWF) plays a key role connecting platelets to subendothelium.

Platelet Function

Vessel injury is required for platelet function.
Exposed subendothelium triggers platelet binding.
Shape change—platelets become spherical, extending pseudopods (extensions).
Granules move toward the platelet surface.
Contents, such as clotting factors, are released.

Platelet Function Diagrams, and further platelet function details

Platelets adhering, activating, and aggregating to form thrombus to stop bleeding.

Tests of Platelet Function

Complete blood count
Blood film
Bleeding time
Platelet function analyzer 100 (PFA-100)
Platelet aggregation tests

Bleeding Time

A clinical test measuring how long it takes for bleeding to stop after a small incision.

PFA-100 (Platelet Function Analyzer)

Automated device measuring platelet function response to collagen and epinephrine.

Platelet Aggregation Tests

Measures how well platelets aggregate in response to various agonists.

Platelet Disorders

Deficiency: Immune thrombocytopenia (reduced platelet production)
Functional: Inherited (Bernard-Soulier, Glanzmann's, Storage Pool Disease) or acquired (Aspirin, Renal failure).

Drug-Induced Autoimmune Thrombocytopenia

Examples of possible symptoms.
Platelet count data associated with a specific case.

Immune Thrombocytopenic Purpura

Characterized by low platelet counts, resulting in bruising and bleeding.
Images illustrating the disease's manifestations.

Aspirin Effect

Aspirin inhibits cyclooxygenase (COX) enzymes, preventing the formation of thromboxane A2, reducing platelet aggregation.

Non-steroidal Anti-inflammatory Agent Therapy (Diclofenac)

Example of possible symptoms.
Images illustrating the condition's effect.

Coagulation Factors

Factors I–XIII are involved in blood clotting.
Most are produced in the liver.
Factors are activated, to create a fibrin clot in a sequential manner.
There are two pathways for factor activation: intrinsic and extrinsic pathways.
Both pathways result in the formation of a fibrin clot.

Coagulation Cascade

A complex series of reactions that lead to fibrin clot formation.
Extrinsic and intrinsic pathways both contribute.
Diagrams showing the cascade and activation of different factors.

Coagulation Tests

Prothrombin time (PT): Measures the extrinsic pathway.
Activated partial thromboplastin time (APTT): Measures the intrinsic pathway.

Thrombin

Thrombin is both a procoagulant and anticoagulant.
Activates factors to create a clot (I, V, VIII, XI, XIII).
Activates platelets.
Activates protein C by binding to thrombomodulin.

Citrate Tubes

Used for coagulation tests to prevent clotting of blood samples.

Automated Coagulometer

Automated machines for accurate coagulation test results.

Common Coagulation Problems

Inherited deficiencies (e.g., haemophilia A, B, Von Willebrand Disease)
Acquired problems (e.g., anticoagulant therapy, DIC)

Factor VIII

Cofactor in the intrinsic coagulation pathway.
Synthesized by reticuloendothelial cells in the liver.
X-chromosome linked gene.
Haemophilia A is associated with deficient factor VIII activity.
Images and examples associated with haemophilia.
Haemophilia A severity linked to factor VIII level.

Thrombosis

Causes of thrombosis are listed.
Venous or arterial thrombosis is mentioned.
Virchow's Triad: risk factors for thrombosis include Hypercoagulable state, endothelial injury, circulatory stasis.
Images including example conditions associated with thrombosis risk factors

Risk Factors for Venous Thromboembolism (VTE)

Conditions and factors that increase risk.
Trauma, bed rest, major surgeries, oral contraceptive use.
Acquired and inherent causes of venous thrombosis.

Laboratory Tests in Haemophilia

Prolonged APTT is a common finding.
Factor assays (VIII and IX) are used to confirm deficiency.

Inherited Risk Factors for VTE

Specific factors and relevant genetic conditions are listed.
Antithrombin, protein C, protein S, factor V Leiden mutations, and prothrombin 20210A.

Natural Anticoagulants

Natural substances that prevent clotting.
These molecules are listed, with their key functions and how they contribute to balancing haemostasis.
Antithrombin, protein C, protein S, and tissue factor pathway inhibitor (TFPI).

Procoagulant Mutations

Factor V Leiden and prothrombin 20210A mutations increase clotting factors’ activity.

Deep Vein Thrombosis (DVT)

Symptoms and examples of diseases relevant to deep vein thrombosis (DVT).
Images illustrating DVT.

Enoxaparin and Warfarin

Anticoagulant drugs for treating or preventing blood clots, illustrated with images of medication packaging and syringes.

Drug-Factor Inhibition

Heparin inhibits factors IIa and Xa.
Warfarin inhibits factors II, VII, IX, X
Specific novel/newer (oral) anticoagulants inhibit other clotting factors.

Warfarin-Induced Intracranial Haemorrhage

Potential side effects from warfarin therapy.
Image showing the condition.

Disseminated Intravascular Coagulation (DIC)

Underlying conditions that can lead to DIC (e.g., sepsis, malignancy, obstetric calamities).
Images associated with DIC.
Complications in the patients are mentioned
Symptoms of DIC, test findings

Laboratory Features of DIC

Microangiopathic haemolytic anaemia
Thrombocytopenia
Prolonged PT, APTT
Reduced fibrinogen
Elevated FDPs (fibrin degradation products), D-dimers

Von Willebrand Factor (VWF)

Synthesized by endothelial cells and megakaryocytes.
Functions include protecting factor VIII and mediating platelet adhesion and aggregation.

Laboratory Diagnosis of Von Willebrand Disease (VWD)

Clinical tests are listed.
APTT, bleeding time, platelet function tests, Factor VIIIc, VWF antigen (VWFAg), and ristocetin cofactor activity, multimer analysis.

DIC Blood Film

Microscopic view of blood showing abnormalities characteristic of DIC (Disseminated Intravascular Coagulation).

DIC Secondary to E. Coli Septicaemia

Complications of sepsis.
Images illustrating clinical symptoms

Processes in DIC

Processes in DIC (Disseminated Intravascular Coagulation), including the cascade (diagram)

Heparin-Induced Thrombocytopenia with Thrombosis (HIT)

Clinical signs and laboratory features of heparin-induced thrombocytopenia and thrombosis.
Images illustrating HIT manifestations.

Vaccine-Induced Prothrombotic Immune Thrombocytopenia

Symptoms following a COVID vaccine
Thrombocytopenia and clot formation risk.
Conditions associated with vaccine reactions.

Thrombosis Risk

Percentage of thrombosis events linked to COVID vaccination, compared to other causes.

Summary

Summary points and key takeaways.

Thank You

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Description

Test your knowledge on the complexities of vascular disorders, specifically focusing on disseminated intravascular coagulation (DIC), Heparin Induced Thrombocytopenia, and Vaccine Induced Prothrombotic Immune Thrombocytopenia. This quiz explores key triggers, consequences, and incidence rates related to these conditions.