Pathophysiology Of Thrombosis

Pathophysiology Of Thrombosis

Write the pathophysiology of thrombosis. Describe the clinical effects.
Answer:

Pathophysiology of Thrombosis

Pathophysiology of thrombosis describes thrombogenesis concerning the normal hemostatic mechanism.

Human beings consist of a system in which blood remains in its fluid state during normal conditions and this system also acts as a guard to stop thrombosis and hemorrhage.

The primary influence over the formation of a thrombus is known as Virchow’s triad. It consists of endothelial injury, altered blood flow, and hypercoagulability of blood.

Pathophysiology of thrombosis

Endothelial Injury

• Blood vessel integrity is important for maintaining the normal flow of blood.
• Injurytobloodvesselleadstoexposureofthesubendothelial connective tissue which a thrombogenic and plays an important role in initiating hemostasis and thrombosis.
• Endothelial injury which leads to thrombogenesis occurs under diabetes mellitus, myocardial infarction, arterial diseases, etc.
• Vascular injury causes loss of epithelium which exposes extracellular material, adhesion of the platelets, the release of tissue factors, and depletion of prostaglandins and plasminogen activators which leads to the formation of thrombus.
• Any disturbance in the balance of prothrombotic and antithrombotic mechanisms of the endothelium of the vessel influences the local clotting mechanism.
• Endothelial dysfunction can lead to the release of more amount of more procoagulant factors which are plasminogen activator inhibitors, various tissue factors, etc.

Altered Blood Flow

• Normal axial flow of blood in its central stream consists of leucocytes and red blood cells. Platelets exist in a slow-moving laminar stream which is adjacent to the central stream and the peripheral stream consists of slow-moving cell-free plasma close to the endothelial layer.
• Both turbulence and stasis occur in normal axial blood flow and disturb it.
• When the speed of flow of blood slows down blood cells containing platelets marginate toward the periphery and form a pavement close to the endothelium.
• As stasis leads to higher release of oxygen from the blood, turbulence injures the endothelium which leads to the deposition of platelets and fibrin.
• Turbulence causes the formation of arterial and cardiac thrombi while stasis leads to the formation of venous thrombi.

Hypercoagulability of Blood

• Hypercoagulability is the alteration in the coagulation pathway that leads to thrombosis.
• It occurs due to the following changes in the composition of blood:
  • Increase in coagulation factors such as fibrinogen, prothrombin, factors 7a, 8a, and 10a.
  • Increase in platelet count and its adhesiveness.
  • Decrease in levels of coagulation inhibitors, i.e. antithrombin 3, firin’ split products.

Clinical Effects of Thrombus

Clinical effects depend on the site of the thrombi, its rapidity of formation, and the nature of the thrombi.

Types of thrombi pathology

• Cardiac thrombi: If large thrombi are present in the heart they can cause sudden death due to mechanical obstruction of blood flow or via thromboembolism to vital organs:
• Arterial thrombi: It can lead to ischemic necrosis of the affected part which can cause gangrene. Sudden death can occur if there is thrombosis of the coronary artery.
• Venous thrombi: It can produce the following effects:
  • Thromboembolism
  • Edema of the area which is drained
  • Poor wound healing
  • Skin ulcer
  • Painful thrombosed vein or thrombophlebitis
  • Painful white leg caused by the file of femoral venous thrombosis in postpartum patients
  • Thrombophlebitis migrants in the cancer

Capillary thrombi: The presence of microthrombi in the microcirculation can lead to disseminated intravascular coagulation.