Thrombus
| Definition |
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- A thrombus is a clotted mass of blood and can occur anywhere in cardiovascular system
| Causes |
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- Physiologically result from normal hemostasis
- Pathologically result from thrombosis
| Categorization |
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- Thrombi are categorized by location:
- Mural Thrombi
- Attached to the wall of the heart chambers or aortic lumen
- Arterial thrombi
- Usually occlusive
- Possess Lines of Zahn: Thrombus has alternate layers of light material (platelets and fibrin) and dark material (RBCs)
- Venous Thrombi (Phlebothrombosis)
- Always occlusive
- Not organized into Lines of Zahn. Just an amorphous mass of RBCs enmeshed in platelets and fibrin.
- Appear 'red', hence termed 'Red or Stasis Thrombi'
- Usually (90%) occurs in veins of lower extremities (See Deep Venous Thrombosis)
- Postmortem Thrombi
- Can develop after death
- Are distinguished by lack of attachment to vessel wall (all others are usually firmly attached)
| Fate of Thrombi |
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- Propagate: Accumulate further fibrin/platelets. Arterial thrombi usually propagate against blood flow. Venous thrombi usually propagate with blood flow.
- Embolization: Thrombus detaches from vessel wall and travels to other sites (See Thromboembolism)
- Dissolution: Fibrinolytic mechanisms dissolve clot
- Organization: Eventually thrombus can be 'organized' via fibrosis and potentially recanalized with new blood vessels.