Chapter 145 - Acute DVT introduction Flashcards
DVT Epidemiology
Men > woman Higher in Hispanic, asian/pacific islanders
In hospital patients with highest risk of DVT
1) acute spinal cord injury 2) trauma 3) neurosurgery 4) ICU patients 5) major orthopedic 6) ward patients
Risk factors of DVT
1) hospitalization 2) surgery 3) trauma 4) cancer 5) chemotherapy 6) varicose veins at young < 60 age 7) congestive heart failure 8) age
Caprini score for DVT risk
FIGURE 145.1
Incidence of DVT from age 30 to age 80
increase 30 fold
Other risks that increase with age and therefore predispose DVT
1) acquired prothrombotic state (higher thrombin) 2) increased stasis in venous valve pockets 3) anatomical changes in soleal veins 4) increase biological markers
Typical clinical scenario in children who acquire VTE
1) scoliosis with halo-femoral traction immobolization 3.7% 2) ICU admission 4% 3) spinal cord injury 10%
Immobilization risk for DVT time line
Increases at 3 days very high risk after 2 weeks
Risk factors for getting DVT in travels
1) no compression stocking 10% risk 2) > 5000 km (150x risk) 3) previous VTE (OR 63.3) 4) trauma (13.6) 5) varicose veins (10) 6) obesity (9.6) 7) immobility during flight (9.3) 8) cardiac disease (8.9)
DVT presented that were recurrences (%)
23-26%
Risk of recurrent DVT with heterozygous factor V Leiden
40% at 8 years 2.4x higher than normal
Percentage of recurrent DVT due to hyperhomocysteinemia
17%
Percentage of first time VTE associated with malignancy
20% 4x higher risk than those without cancer
Cancer types associated with highest VTE risk
1) pancreas ++ 2) kidney 3) ovary 4) lung 5) stomach
Mechanisms in which cancer may increase VTE
1) mass effect venous compression 2) thrombocytosis 3) immobility 4) indwelling central lines 5) chemotherapy 6) radiation therapy 7) Tumor increase TF expression –> activate FX and XI –> thrombin 8) cancer procoagulant –> activate FX 9) platelet adhesion to tumor cells via glycoprotein Ib and IIb/IIIa
Difference between TF and CP in activating factor X
TF requires FVII CP activates X without FVII
How does IL-1 and TNF alpha cause VTE
1) downregulate thrombomodulin (thrombin receptor) on endothelial surface –> decrease thrombin-thrombomodulin complex –> decrease protein C activation 2) stimulate PAI-1 production –> inhibit fibrinolysis
Most common abnormalities in coagulation parameter in cancer
1) elevated fibrinogen 2) thrombocytosis 3) elevated coagulation factor 4) elevated fibrin degradation product 5) lower protein C and S
Coagulation peptide that reflect tumor activity
Fibrinopeptide A
Risk of DVT in treatment for non-Hodgkin’s lymphoma
6%
Risk fo DVT in treatment for breast cancer
17.5%
Chemotherapy mechanism in causing DVT
1) direct endothelial toxicity 2) hypercoagulable state 3) reduced fibrinolytic activity 4) tumor cell lysis 5) central venous catheters
Marker for increased risk in cancer patients for DVT
soluble P-selectin
Strongest predictor from the VA study on post-surgery DVT
1) MI 2) blood transfusion > 4 units 3) UTI
Risk of VTE in pregnancy
6-10x 1.3-7% during 6.1-23% postpartum
% of DVT in pregnancy in the left leg
97%
Mechanism of increased DVT in pregnancy
1) compression 2) transient hypercoagulable state
Hypercoagulable state in pregnancy
1) Increased fibrinogen, vWF, F2, 7, 8, 10 2) resistance to activated protein C 3) reduced protein S level
Fibrinolytic system alternation in pregnancy
1) decreased tpa 2) increased PAI 1 and 2
Percent of pregnancy-associated VTE that also have inherited thrombophilia
30-50%
Risks associated with VTE in postpartum stage 6 weeks
1) maternal age 2) suppression of lactation 3) hypertension 4) assisted delivery
Effects of estrogen in altering coagulation system
1) decrease PAI12 2)increase blood viscosity 3) increase fibrinogen 4) increase factor 7 and 10 5) increase platelet adhesion and aggregation 6) decrease antithrombin and protein S
Factors that compound with oral contraceptives to increase DVT
1) surgery 2) Factor V Leiden 3) resistance to protein C 4) smoking
Blood group associated with higher and lower risk of VTE
Type A higher Type O lower (less vWF)
Ethnicity of DVT risk
1) highest in Europe 2) higher in central US
Other non-coagulopathic diseases that increase DVT risk
1) UC 2) SLE 3) varicose veins
First discovery that L > R for DVT risk
Virchow
First cadaver study to show that right iliac artery can cause intimal hypertrophy of left iliac vein
May and Thurner
Cockett syndrome
Cockett 1965 iliofemoral DVT secondary to compression of iliac vein surgical intervention can alleviate skin ulcers now called May Thurner syndrome
May Thurner Syndrome key points
1) young to middle age 2) women 3) after multiple preg
Anatomical rate of left iliac vein compression
22-32%
Rate of left leg edema or DVT that also have iliac vein compression
37-61%
Association between AAA and May Thurner
less chance because iliac artery more tortuous
Popliteal vein entrapment key points
1) 10% with artery 2) 70% in females
Obesity and DVT
1) not a risk factors for development of DVT 2) risk factor for recurrent DVT
Rate of recanalization after acute DVT at 3 and 9 months via impedance plethysmography
67% in 3 months 92% in 9 months
Rate of recanalization after acute DVT at 7 days and 90 days by duplex
44% at 7 days 100% at 90 days
Generally within what time frame do most thrombus resolution after acute DVT occur
3 months
DVT recurrence in 10 years
30%
Risks for recurrent DVT
1) age 2) obesity 3) cancer 4) paresis
Rate of PE in hospitalized patients autopsy and rate of PE-related mortality
26% found at autopsy 9% was cause of death
