Thrombus a solid mass consisting of blood constituents
within the blood vessel; attached to the point of origin.
Thrombosis the process of…
Clot mass of coagulated blood
Haematoma extravascular accumulation of blood clot
Haemostatic plugs normal clots to control bleeding
Thrombus and Thrombosis
Ulcerated plaque in
Haemodynamic stress in HTN
Exogenous chemical agents
Turbulent flow of blood in
Mural thrombus following
Causes of endothelial injury
Turbulence: unequal flow (arterial); may aggravate
vascular injury as well.
Stasis: slowing (venous)
Blood cells and platelets migrate to periphery and
pavement the endothelium
Normal flow has:
Central fast moving red and white blood cells.
Slow moving laminar stream of platelets.
Peripheral slowest moving cell-free plasma.
Alteration of blood flow
Prevent dilution by fresh flowing blood of activated clotting
Disrupt laminar blood flow and bring platelets in contact of
Retard the inflow of clotting factor inhibitors and permit
Promote endothelial cell activation
DVT of lower limbs
Thrombosis in aneurism
Use of OCPs
Increased coagulation factors
Increased platelet count and adhesiveness
Decreased levels of coagulation inhibitors
Deficiency of anti thrombin
Deficiency of protein C or S
Defects in fibrinolysis
Mutation of factor V
Sedentary life style
Clinical conditions leading to
Heart diseases (MI, CHF, RHD)
Late pregnancy and puerperium
Factors favoring thrombosis
Shape and size depends on origin
Arterial white and mural (firm and pale)
Venous red and occlusive(soft, red and gelatinous)
Mixed/ laminated – alt white and red layers separated by
line of ZAHN.
Lines of Zahn seen where visible
Collection of cells and fibrin
Based on colour and components:
Pale – primarily platelets
Red – primarily RBCs
Mixed – visible lines of zahn
Based on site and mode of formation:
Mural – occurs in heart chambers/ aorta/ major arteries
Based on infection:
Bland – non infected
Septic – infected.
Resolution – plasmin may dissolve the thrombus
Organization – eventually covered by endothelial cells
after granulation tissue formation (or calcification/
Propagation – enlargement of size may block
Thromboembolism – detachment and released into
Fate of thrombus
The process of partial or complete obstruction of
some part of the CVS by any mass carried in the
Commonly thromboembolism (90%)
What is it?
Depending on matter of embolus
Solid- thrombus, atheroma, malignant cell, parasites, foreign
Liquid- fat globules, amniotic fluid, bone marrow
Gasseous- air, other gasses
Depending on infection:
Depending on source of emboli:
Cardiac emboli from left side of the heart – vegetations of
endocarditis, atrial appendages
Arterial – in systemic arteries of brain, spleen, kidney and
Venous – in pulmonary arteries
A detached thrombus or a part of thrombus.
Site of lodgement:
Most common and fatal form.
Occlusion of the pulmonary arterial tree.
Pulmonary thrombosis (rare)
More common in bed ridden patients.
Thrombi originating from large veins of lower legs
(popliteal, femoral and iliac)
Less common sources ( varicosities of superficial veins,
Detachment of thrombus thromboembolism
drains into right atrium.
Large thrombus is impacted at the bifurcation of main
pulmonary artery (saddle embolus) or on RV or its
If large embolus fragments small embolus impacts
in a number of vessels (esp. on lower lobes of lungs)
Paradoxical embolism – passage of embolus from rt.
heart to lt. heart via ASD or VSD.
Sudden death – d/t massive pulm. Embolism.
Acute cor pulmonale – RHF d/t pulmonary HTN
Pulm. Infarction – obstruction of small pulm. arteries.
Pulm. Haemorrhage – central pulm. Haemorrhage d/t obstruction of
flow in endarteries.
Resolution – 60-80 % by fibrinolysis.
Pulm. HTN, chronic cor-pulmonale and pulm.
Esp. originating in LV (MI, cardiomyopathy, RHD,
congenital heart disease, IE, prosthetic valves)
Site of origin:
Aorta – thrombi over ulcerated atheroma in aortic
Paradoxical – rt. lt. in ASD or VSD
Idiopathic – 10-15%
Embolism of fat globules.
Obstruction by fragments of adipose tissue fat
Trauma to bones, trauma to soft tissue
Non traumatic –
Burns, DM, fatty liver, pancreatitis, decompression
Mechanical obstruction – micro aggregates of fat
causes obstruction of vessels.
Chemmical injury – FFA causes toxic injury.
Thrombocytopenia – d/t coating of fat globules with
Pulmonary fat embolism
Systemic fat embolism (in case of ASD/ VSD)
Air, nitrogen and other gases,
Air embolism – entry of air due to trauma, injury or surgery.
Decompression sickness/ caisson’s disease, diver’s palsy or
aeroembolism seen in deep sea divers.
During delivery or abortion
Acquired/ accidental pneumothorax
Accidental opening of large veins
Cardiothoracic surgery / trauma
Most serious, unpredictable and unpreventable cause of
Amniotic fluid may contain – epithelial squames, vernix caseosa,
lanugo hair, bile from meconium and mucus
Sudden respiratory distress and dyspnoea
Amniotic fluid embolism
Mechanical blockage of pulmonary circulation in
Anaphylactic reaction to components
DIC d/t liberation of thromboplastin
Haemorrhagic manifestations d/t thrombocytopenia
Cause of death