DVT Flashcards
Where does DVT normally occur?
Deep veins of legs
How can DVT be categorised?
Distal- calf. Proximal- popliteal or above
What 4 veins are most VTEs in?
Anterior and posterior tibial, peroneal, popliteal
How does DVT happen?
Stagnant pool of blood in recesses just above venous valves clots due to activation of intrinsic pathway.
Why does DVT occur in deep veins not superficial veins?
Superficial veins have less blood flow, are less reliant on muscle contraction, and have more sympathetic control.
What is Virchow’s triad?
3 causes of VTE. reduced blood flow, vessel wall pathology, hypercoagulability.
What can cause reduced blood flow?
Long haul flights, immobilisation due to illness etc, obesity, sickle cell, surgery
What do prostacyclin and nitric oxide do?
Vasodilation and inhibition of platelet activation.
What is heparin sulphate?
Expressed in healthy endothelial cells on transmembrane protein backbones of differing lengths. Forms non stick surface and prevents platelet adhesion
What can lead to vessel wall pathology?
Chronic inflammatory disease such as rheumatoid arthritis, IBS, cancer. Reduces anticoagulant/ platelet factors. Smoking causes endothelial damage.
What is endothelin?
Powerful vasoconstrictor secreted by the endothelium. Can be released in response to hypoxia, oxidised LDLs, inflammatory cytokines, bacterial toxins.
When might there be high endothelin levels?
Endothelial cell injury, essential hypertension, congestive heart failure.
What can cause blood hypercoagulability? (5)
Genetic conditions like factor V Leiden. Blood group O has reduced risk. Cancer- cells can secrete procoagulants. Pregnancy- estrogen associated with increased risk. History is a major risk factor.
What is the typical presentation of DVT?
Distributed inflammation- pain, swelling, oedema, warmth, superficial venous dilation
What differentials could there be?
Musculo-tendinous injury, cellulitis, CHF, hypoalbuminaemia, lymphoedema, fracture, tumour, synovitis, acute arterial occlusion etc
