Thrombosis and Virchow's Triad

A thrombus is a blood clot attached to a vessel wall, while an embolus is a blood clot that travels in the bloodstream.

Platelets stick to damaged blood vessel surfaces, binding to exposed collagen.

Platelets change shape and release chemicals (like ADP and thromboxane A2) to recruit more platelets.

Platelets clump together by binding to fibrinogen, creating a growing plug.

Thrombin converts fibrinogen to fibrin; fibrin strands form a stable clot.

The process of dissolving a blood clot after healing is complete.

Healthy endothelium releases prostacyclin and nitric oxide to prevent platelet aggregation.

Thrombosis is the formation of a blood clot (solid/semiliquid mass) in a blood vessel during life.

Deep vein thrombosis (DVT) is a blood clot that forms in a deep vein, usually in the legs. It can cause pain, swelling, and redness in the affected area.

People with a higher risk of DVT include middle-aged and elderly individuals, those who have recently had surgery, or those with certain medical conditions.

An embolus is a detached piece of material that travels through the bloodstream and blocks a blood vessel.

A pulmonary thromboembolism (PTE) occurs when a blood clot travels to the lungs and blocks a blood vessel.

Most PTEs originate in DVTs in the legs, specifically the calf muscles and femoral veins.

The outcomes of PTE vary depending on the size of the clot and the patient's overall health. Possibilities include asymptomatic cases, sudden death, pulmonary infarction, and pulmonary hypertension.

Pulmonary infarction is tissue damage in the lungs caused by a blocked blood vessel.

DVTs can break off and travel to the lungs, causing a PTE.

Three factors that lead to thrombus formation: endothelial injury, changes in blood flow, and changes in blood composition.

Damage to the inner lining of blood vessels, promoting thrombus formation.

Blood flow that is abnormally slow, or turbulent. contributing to thrombus (blood clot) formation.

Factors like abnormal platelet activity, increased red blood cells, or higher fibrinogen levels contribute to blood clotting.

A blood clot formed within a blood vessel.

A dislodged thrombus that travels through the bloodstream.

Thrombi can propagate (grow), embolize (travel), dissolve, or become organized and recanalized.

Emboli travel through the systemic circulation, often originating from the left side of the heart due to conditions like prosthetic heart valves, rheumatic heart valve disease, or infective endocarditis.

Emboli that lodge in arteries, almost always causing an infarction (tissue death) due to lack of blood flow.

An infarct caused by an infected embolus, leading to abscess formation.

An infarct with bleeding, often due to venous occlusion, loose tissue, or a double blood supply (like in the lungs).

An infarct without bleeding, typically caused by arterial occlusion in solid organs like the heart, kidney, or spleen.

Infarcts are typically wedge-shaped, with the apex (point) pointing towards the vascular occlusion and the base forming the periphery of the organ.

A heart attack caused by an occlusion of a major coronary artery, usually a white infarct.

The severity of an infarction depends on the size of the embolus and the location it blocks. A small embolus in a minor artery might be less dangerous than a larger one in a critical vessel.

A blood clot that floats in the bloodstream.

Thrombin converts fibrinogen into fibrin, creating a stable clot.

Tissue death caused by blockage of a blood vessel.

Deep vein thrombosis is a blood clot that forms in a deep vein, usually in the legs. It can cause pain, swelling, and redness.

DVT symptoms include local pain, heat, and edema (swelling) in the affected leg.

Middle-aged and elderly individuals, those who have recently had surgery, and those with certain medical conditions are at higher risk for DVT.

A pulmonary thromboembolism occurs when a blood clot travels to the lungs and blocks a blood vessel.

Most PTEs originate from DVTs in the legs, particularly in the calf muscles and femoral veins.

Outcomes of PTE can range from asymptomatic cases to sudden death, depending on the size of the clot and the patient's health.

A blood clot growing larger and thicker by accumulating more platelets and fibrin.

The process of new blood vessel channels forming within a clot, allowing blood to flow again.

Increased pressure in the pulmonary arteries, often caused by obstruction of small branches due to repeated showering of small thrombi (small blood clots).

Systemic thrombi (blood clots) often impact in the lower extremities (legs), brain, mesenteric vessels (intestines), spleen, and less commonly the upper extremities (arms).

A heart attack caused by blockage of a major coronary artery, usually a white (anemic) infarct causing tissue death.

The severity of an infarction depends on the size of the embolus and the location it blocks. A small embolus in a minor artery might be less dangerous than a larger one in a critical vessel.