Haemostasis and the coagulation cascade
Haemostasis depends on an intricate series of events involving platelets, other cells and the activation of specific blood proteins, known as coagulation factors6
Haemostasis or normal thrombus formation is essential for survival
Haemostasis is the normal physiological response that prevents significant blood loss following vascular injury.6 Knowledge of the process of haemostasis is important in order to understand the major disease states associated with thrombosis, such as:
- Venous thromboembolism (VTE)
- Atherothrombosis (thrombosis triggered by plaque rupture)
- Cardioembolic stroke
When blood vessel injury occurs, physiological haemostasis is triggered and the following sequence of events take place:
- The vessel constricts to reduce blood flow
- Circulating platelets adhere to the vessel wall at the site of trauma
- Platelets are activated and aggregate
- An intricate series of enzymatic reactions occur involving coagulation proteins
- Fibrin is produced to form a stable haemostatic plug
Haemostasis is a finely tuned process. It serves to maintain the integrity of the circulatory system.10 However, the process can become imbalanced, leading to significant morbidity and mortality.11
Haemostasis schematic
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Yahoo! My Web- 6 - Colman RW, Clowes AW, George JN, Goldhaber SZ, Marder VJ. Overview of hemostasis. In: Colman RW, Marder VJ, Clowes AW, George JN, Goldhaber SZ, eds. Hemostasis and Thrombosis: Basic Principles and Clinical Practice. 5th ed. Philadelphia, PA: Lippincott, Williams & Wilkins; 2006:3-16.
- 10 - Adams GL, Manson RJ, Turner I, Sindram D, Lawson JH. The balance of thrombosis and hemorrhage in surgery. Hematol Oncol Clin North Am. 2007;21(1):13-24.
- 11 - Heit JA. Venous thromboembolism: disease burden, outcomes and risk factors. J Thromb Haemost. 2005;3(8):1611-1617.
- Haemostasis
- The prevention of blood loss, either by the physiological properties of vasoconstriction and coagulation or by surgical means.
- Vascular injury
- Damage to the endothelial layer (inner surface) of a blood vessel. This damage causes the release of tissue factor, which subsequently activates Factor X. Vascular injury can be caused, for example, by incisions made during surgery, the use of catheters, or the use of a tourniquet.
