Thrombosis and embolism NOT DONE

Define thrombosis

Solidification of blood contents that forms within the vascular system.

Virchows triad

• changes in the intimal surface of the vessel (endothelial damage)

• changes in the pattern of blood flow (abnormal blood flow)

• changes in the blood constituents (hypercoagulability)

Appearance of an arterial thrombus + its effects

• Pale

• Line of Zahn

• Lower cell content

Effects : ischaemia, infarction

Appearance of an venous thrombus + its effects

• soft

• Red

• Gelatinous

• Higher cell content

Effects: congestion, oedema, skin ulceration

What are the different outcomes of a thrombus?

• Lysis (if the thrombus is small)

• Propagation - progressive spread of thrombosis

• Organisation- Ingrowth of fibroblasts and capillaries with the lumen remaining obstructed

• Recanalization- Ingrowth of new vessels → new vessels join up to restore blood flow

• Embolization - fragmentation of the thrombus → infarction at a distant site

Where can different thrombuses form and where can they embolise?

From systemic veins: pass to the lungs to form pulmonary emboli

• From the heart pass via the aorta to renal, mesenteric, and other arteries

• From atheromatous carotid arteries pass to the brain to cause stroke.

• From atheromatous abdominal aorta pass to arteries of the legs

Pre-disposing factors for deep vein thrombosis

Immobility/bed rest

• Post-operative

• Pregnancy and postpartum

• Oral contraceptives

• Severe burns

• Cardiac failure

• Cancer (hypercoagulability)

What is a paradoxical embolism?

occurs when a blood clot or other embolus travels from the venous system (right side of the heart) to the arterial system (left side of the heart) through a right-to-left shunt → due to defect like patent foramen ovale

What is a saddle embolism?

Embolism affecting both sides of the bifurcation of a vessel eg. Abdominal aorta

Fat and bone marrow embolism, amniotic embolism

Prevention and treatment of thromboembolic diseases

General precautions: exercise, Weight, compression socks etc

• Aspirin

• Heparin

• Warfarin → affects vit K

• Filters