Bleeding complications in cancer patients can be potentially life-threatening if not adequately and promptly recognized and treated. The most frequent haemostatic defect causing bleeding in this setting is thrombocytopenia. Other disorders are represented by liver insufficiency with or without vitamin K deficiency, disseminated intravascular coagulation (DIC), inappropriate or excessive use of anticoagulants, as well as acquired haemophilia A and acquired von Willebrand disease.
Importance of Accurate Diagnosis & Management
Impact of Bleeding Disorders on Quality of Life
•Physical Limitations
•Chronic Pain and Joint Damage
•Emotional and Psychological Impact
•Educational Disruptions
•Financial Burden
Overview of Haemostasis
Platelet Adhesion: The GPIb/V/IX receptor complex on platelets binds to vWF initiating platelet adhesion to the damaged site.
Platelet Activation: Following adhesion, internal signals increase intracellular calcium levels, leading to:
Increased intracellular calcium, which triggers further activation steps.
Increased exposure of phosphatidylserine, creating a negatively charged surface which supports the assembly of coagulation factors.
Release of contents from alpha and dense granules, enhancing the platelet activation and recruitment process.
This image illustrates the key components and mechanisms involved in platelet activation and aggregation, which are central to hemostasis and thrombus formation. The platelet surface expresses glycoprotein receptors, such as GPIb/V/IX, which interact with Von Willebrand factor to mediate initial adhesion to collagen in the subendothelial matrix. Activation leads to intracellular calcium (Ca²⁺) mobilization, triggering the release of alpha (α) granules (containing platelet factor 4 (PF4) and platelet-derived growth factor (PDGF)) and dense (δ) granules (which release ADP and serotonin) to amplify the activation process. P-selectin, a marker of platelet activation, facilitates interactions with leukocytes. The conversion of arachidonic acid into thromboxane A2 promotes further platelet recruitment and aggregation through αIIbβ3 integrins, which bind fibrinogen to form a stable clot. Additionally, cytoskeletal changes aid in platelet shape modification, enhancing thrombus formation. This image effectively summarizes the complex interplay of biochemical and structural changes that drive platelet-mediated hemostasis and thrombosis.
Platelet Aggregation:
Activation leads to a conformational change in the GPIIb/IIIa receptor, enabling it to bind fibrinogen with high affinity, facilitating platelet-platelet interactions (aggregation).
Generation of TXA2 amplifies the activation signals and promotes further aggregation.
Cytoskeletal reorganization helps in stabilizing the forming platelet plug.
Coagulation Cascade
This image illustrates the coagulation cascade, which consists of the extrinsic and intrinsic pathways converging into the common pathway to form a stable fibrin clot. The extrinsic pathway is triggered by tissue injury, where tissue factor (III) activates factor VII, leading to factor X activation. The intrinsic pathway is initiated by exposure to a negatively charged surface, activating factor XII, which sequentially activates factors XI, IX, and VIII. Both pathways converge at factor X, which, along with factor V, forms the prothrombinase complex, converting prothrombin (II) to thrombin (IIa). Thrombin then converts fibrinogen (I) into fibrin (Ia) to form a clot, stabilized by factor XIIIa. Regulatory mechanisms, such as antithrombin III and activated protein C, help control excessive clotting.
Fibrinolysis Pathway
This image illustrates the fibrinolysis pathway, where plasminogen is activated by tissue plasminogen activator (tPA), urokinase, kallikrein, and contact activation to form plasmin, which breaks down fibrin into fibrin degradation products. This process is regulated by plasminogen activator inhibitors (PAI-1 & 2) and α2-antiplasmin to prevent excessive clot breakdown. Tranexamic acid (TXA) and epsilon-aminocaproic acid (EACA) inhibit plasminogen activation, reducing fibrinolysis and stabilizing clots.
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