Lecture 21 - Thrombosis Flashcards
1
Q
Common sites of thrombosis
A
- arterial: coronary artery (MI), cerebral artery (stroke), femoral artery (peripheral vascular disease)
- Venous: pelvic, leg veins (DVT), Pulmonary artery (PE), hepatic, portal v (Veno-occlusive disease), cerebral vein (sinus thrombosis)
- other sites: heart valves: bacterial endocarditis
- multiple DIC
2
Q
Arterial thrombosis
A
- atherosclerosis
- endothelial disruption
- platelet activation
- forms a platelet rich WHITE thrombus
3
Q
Risk factors for arterial thrombosis
A
- Major: age, male, race,family hx, hyperlipidemia, hypertension, smoking, diabetes mellitus
- Minor: obesity, physical inactivity, stress/personality, other dietary factors, oestrogen deficiency, lipoprotein profiles, homocysteine
4
Q
Atherosclerosis triggers arterial thrombosis
A
- normal vessel -> fatty streak -> fibrous plaque/calcification/hemorrhage -> plaque rupture, thrombosis
5
Q
Therapy of arterial thromboembolism
A
- Aspirin: and/or other antiplatelet agents for threatened occlusion, improves survival after MI
- Heparin - unstable angina
- thrombolysis: streptokinase, tPA used acutely in MI, local urokinase in peripheral arterial occlusion
- warfarin: only after initial heparin therapy, used for long term prophylaxis, prevention
6
Q
Antiplatelet agents
A
- COX inhibitors: aspirin, NSAID, Cox1/2
- phosphodiesterase inhibitors: dipyridamole
- ADP receptor inhibitors: clopidogrel
- GPIIb-IIIa antagonists: abciximab, tirofiban
- others: Serotonin antagonist, PAF antagonist
- newer agents are often more potent than aspirin but are more toxic and expensive
7
Q
Venous thrombosis
A
- Venous obstruction
- impaired flow - stasis
- coagulation factor activation
- forms an erythrocyte-rich RED thrombus
8
Q
DVT vs PE
A
- about 50% of patients with proximal DVT of the lef have asymptomatic PE
- DVT is found in around 80% of patients with PE (mainly asymptomatic)
9
Q
Diagnosis of VTE
A
- most are clinically silent, proximal or distal
- 1cm
- differential Dx: MSK problems, impaired venous and lymphatic outflow, popliteal inflammatory Baker’s cyst
- clinical suspicion mandates confirmation
10
Q
Superficial thrombophlebitis
A
- saphenous veins, varicose veins, IV catheters, migratory superficial thrombophlebitis
- trousseau’ sign - carcinoma
- tender cord, erythema, oedema
- low embolic risk
11
Q
Diagnostic techniques
A
- ascending phlebography: contrast induced thrombosis of peripheral veins 2-3%, cost, time consuming
- duplex ultrasonography: symptomatic proximal DVT: sensitivity 93%, specificity 98%. Much lower sensitivity for detection of distal thrombu and in screening of asymptomatic patients
12
Q
Upper limb thrombosis
A
- 1-2% of all DVT
- pain, swelling of upper extremity
- effort or exercise induced: hyperabduction, external rotation
- trauma to axillary or subclavian vein, absent in 13-32%
- thoracic outlet syndrome: first rib, fibromuscular band, clavicle, muscle hypertrophy
- central venous access devices
13
Q
Risk factor for venous thrombosis
A
- prior history of VTE
- malignancy
- immobilisation
- heart failure
- pregnancy, OCP, HRT
- inherited prothrombotic factor
- age, obesity
- antiphospholipid antibodies: LA, ACA
- dehydration
- infection, indwelling central venous catheters
14
Q
Post thrombotic syndrome
A
- chronic complication of DVT, 1/3 pts, severe in 5-10%
- clinical diagnosis: symptoms intermittent or persistent, aggravated by standing or walking, relieved by rest and elevation, aching, heaviness swelling cramps, itching and tingling
- signs: oedema, permalleolar telangiectasia, brown pigmentation, venous eczema, secondary varicose vein, ulceration
15
Q
Post thrombotic syndrome
A
- risk factors: persistent LL symptoms, anatomically extensive DVT, recurrent extensive DVT, recurrent ipsilateral DVT, obesity, advanced age
- treatment: compressions
