The Use Of Anticoagulant Therapy And Its Effects On The Treatment

1577 Words Jan 11th, 2015 7 Pages
Introduction
Epistaxis is defined as the occurrence of haemorrhage from the nose, which is relatively common and does not always need professional medical attention. However, prolonged or repeated events of nosebleeds, also known as 'recurrent idiopathic epistaxis ' may indicate certain bleeding disorders or potential adverse effects from the use of anticoagulant therapy. Warfarin (Coumadin) is a common anticoagulant that affects clotting factors that are produced in the liver. It is often administered after an myocardial infarction in order to prevent thrombosis and thromboemobolism which could lead to the development of a stroke, most of which are ischemic in origin. Despite its effectiveness, warfarin has been implicated in 50
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The formation of a thrombus represents the second stage of hemostasis, following vasoconstriction and platelet aggregation at the site of injury. The clotting process is very complex and its role is to maintain vascular integrity and to induce rapid clot formation after a vascular injury. It is vital to be able to regulate the production of thrombin, in order to prevent thrombosis, as well as maintaining normal blood circulation.
As shown by figure 1, the coagulation cascade is a protein based system which is initiated through the activation of two separate pathways designated extrinsic and intrinsic. These two pathways proceed through the common pathway of coagulation until fibrin is formed. The extrinsic pathway is generally the first pathway to be activated, and it is stimulated by tissue factor 'thromboplastin ' coming into direct contact with factor VII. Factor VII is then converted to its active form, factor VIIa. In the coagulation cascade, an activated factor functions as an enzyme that activates the next factor until fibrin is formed. Once activated, factor VIIa activates factor IX and factor X. The activation of factor Xa from factor VIIa is inhibited by tissue factor pathway inhibitor. Instead, factor Xa requires calcium and co-factor F5a to form the prothrombinase complex, which activates prothrombin to thrombin (FIIa). Thrombin represents the most important constituent of the coagulation cascade because of its feedback activation roles.
In contrast,
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