Thromboembolism ,DVT Flashcards
What does hypercoagulable state mean
A person in this state has a higher than normal tendency to clot due to increased procoagulants or decreased antocoagulants
In what cases will you suspect hypercoagulable state
- Spontaneous thrombosis without obvious risk factors
- A family history of recurrent venous thrombosis at early age
- Thrombosis with concomitant risk factor at an early age
- Thrombosis at unusual site, i.e vessels in arm or organ
- recurrent thrombosis
Balance of coagulation in hypercoagulable state
tipped towards thrombosis
Diseases involved in hypercoagulable state
Myocardial infarction
Cardiovascular disease
Deep vein thrombosis
Peripheral arterial disease
General areas thrombosis occurs
Arterial and venous system
Risk factors for arterial thrombosis
Family history of arterial thrombosis Male sex Hypertension Cigarette smoking Hyperlipedimea
Risk factors for venous thrombosis
Virchow’s triad
Stasis
Hyper coagulopathy
Vessel wall damage
age
sex
obesity
Causes of hypercoagulability disorders
Hereditary hemostatic disorders i,e factor 5 leiden
Hereditary and acquired hemostatic disorders i.e raised levels of factor 7,8
How is stasis a risk factor/ what causes stasis
Cardiac failure- sluggish flow of blood
Hereditary prothrombotic factors
Elevated levels of
Fibrinogen- factor 1
Prothrombin - factor 2
What is factor 5 leiden
A mutated form of factor 5, given the name factor 5 leiden which is resistant to cleavage by activated protein c complex
Normal action of factor 5
Factor 5 is supposed to be cleaved by protein C ( anticoagulant) in order to stop its procoagulant activity to ensure it doesn’t overwork
A mutation–. resistance…..> Persistent procoagulant activity
Most significant genetic risk factor for thrombosis
Factor 5 leiden
Prevalence in caucasians
5%
Thrombotic risk for heterozygotes
6-8 fold
Thrombotic risk for homozygotes with factor 5 mutation
80 times risk
This contributes to risk of thromboembolism
Elevated factor 8
Elevated von Willebrand factor - also an independent risk factor for MI or stroke
Inhibitors of hemostasis
Protein c, protein s
Tissue factor pathway inhibitor
Antithrombin
Acquired prothrombotic risk factors
- Central venous catheter used as supportive management by being placed in the vein to keep it patent is an important risk factor for thrombosis
- Malignancies. Thromboembolism is a complication of cancer. Chemotherapy as well as complex interaction of factors play a role. Malignancies also cause immunosuppression;–>infection, dehydration(stasis)
- Sepsis
- Congenital heart dx
- hypovoleamia
- Trauma/surgery
7 immobilization - Estrogen containing contraceptives
9.Steroids - Nephrotic syndrome
Prevalence of CVC related DVT
1-70%
Screening test for hypercoagulability
FBC, expected to be high and will cause stasis
Myeloproliferative disorders
Shortened PT/APTT
High factor assay
Deficiency in anticoagulants i.e assay for protein C and S
Protein C resistance test
Deep vein thrombosis
Formation of blood clot in the deep leg vein which may lead to post thrombotic syndrome
Prevalence im US
600.000 cases
Prognosis of DVT
1 out of 100 people die
Risk factors for DVT
Previous DVT Family History Recent surgery greater than 40 Hormone therapy/ oral contraceptives pregnancy / post partum Previous or current cancer limb trauma/ orthopedic procedure coagulation abnormality Obesity
Symptoms of DVT
Discoloration of legs Swelling of leg Calf or leg pain Warm skin Visibility of surface veins Leg fatigue
Diagnosis of DVT
Serial compression ultrasonography which may be combined with doppler
contrast venography
Plasma D-dimer conc
MRI
Anticoagulant drugs for DVT
Unfractionated heparin
LMW heparin
Anticoagulant prevents further formation of the clot whiles the body compensates for thrombus already formed. it doesnt lyse thrombus
Precautions when using unfractionated heparin
Monitor with APTT because you dont want to over/under anticoagulate your patient.
APTT should be 1.5-2.5 times the normal APTT
Dosage of unfractionated heparin
Continous IV or intermittent subcutaneous, i.e every 12 hrs
Advantage of LMW heparin
No need to monitor with APTT
Given once a day
When bleeding occurs with heparin what do you do
Reverse effect with protamine
1mg/100 units
Common oral anticoagulant
Warfarin
How to monitor warfarin
With INR
Target INR for warfarin in DVT, atrial fibrillation, Pulmonary embolism, cardioversion
Ideally 2.5 but between 2-3
Target INR for warfarin therapy in recurrent DVT on warfarin, mechanical heart valves, Antiphospholipid syndrome
Ideally 3.5 but 3.0-4.0 okay
How many hours does it take for warfarin to work
72 hrs. it is first procoagulant before becoming anticoagulant.
Starting therapy with just warfarin is not wise due to delay in onset and initial procoagulant activity
When starting warfarin therapy do this
Give warfarin plus LMW/Unfractionated heparin whose anticoagulant effect starts immediately before warfarins anticoagulant activity can set in after 72 hrs
Warfarin preferred to heparin because
it is administered orally
When someone is on warfarin avid these foods
Green leafy vegetables rich in vitamin k. Warfarin is a vitamin K antagonist. Their work ends up cancellimg out
What foods can cause INR to shoot up/ potentiate warfarin
Citrus fruits
Warfarin overdose manifests as
High INR
If INR is between 3-6 what do you do
Ideal is supposed to be 2.5 . I will reduce dose or stop and restart at another time
If Ideal INR is 3.5 and INR of patient is 4-6
Reduce/stop
Restart when INR less than 5
If INR is 6-8 with no bleed
Stop and start when INR is less than 5
If INR is greater than 8 with no or minor bleed
You stop and restart when INR is less than 5
You may give vitamin K
If INR is greater than 8 with major bleed
Stop warfarin and give fresh frozen plasma, vitamin k, prothrombin complex
Under heparin clot resolves in
5-14 days
Thrombolytic drugs
Rarely used except i emergency
Dissolves the clot
eg. streptokinase, urokinase
Therapy for thrombosis
Surgical embolectomy
Anticoagulant
Antithrombolytic drugs
Newer drugs for DVT
Heparinoids
Oral Direct FX inhibitor
Oral direct FII inhibitor
Post thrombotic syndrome
Common complication of DVT treated with anticoagulant alone
Pathophysiology of PTS
Anticoagulant therapy–> Body tries to dissolve clot–> Destruction in valves of veins–> pooling of blood—> thrombosis can recur
DVT can cause
Pulmonary embolism
Risk of getting pulmonary embolism from DVT is reduced with
Early treatment. Chances reduced to 1 percent
