Chap 49 DVT Flashcards
What are RF for DVT
hospitalizations recen surgery trauma cancer indwelling catheter extermity paresis varicose veins CHF increasing age long-haul travel thrombophilia pregnancy OCP IBD antiphospholipid antibodies iliac vein compression
What % of sympto DVT have PE?
50%
What is post thrombotic syndrome? What is the mechanism? what are RF?
50% of DVT
pain, edema, heaviness, hyperpigmentation, ulceration
this is a consequence of valvular reflux, persistent venous obstruction,
generally thrombus does not adhere to valves secondary to likely endothelial properties. Protective mechanism fails then contribute to post-throbotic syndrome
higher rates of PTS in anticoag alone vs thrombolysis in CaVent study
RF rate of recanalization, anatomic distribution of reflux and obstruction, extent of reflux, recurrence, BMI, influence occurrence of PTS
Chronic venous insuff in DVT/PE 1, 5, 10, 20 year 7%, 15%, 20%, 27%
Incidence of venous ulcers 4%
What are features of DVT on DUS?
Absence of spontaneous flow Absence of flow augmentation Visible thrombus Absence of compressability Absence respiratory phasicity
How to distinguish DVT acute from chronic?
acute vs chronic
total occlusion vs partial clot retracted vs adherent clot compressibility soft vs firm smooth vs irregular homo vs hetero fain echolucent vs echogenic no collaterals vs present
Pitfalls in DVT identification?
Misidentification of veins
Missing duplicate venous system,
Systemic illness of hypovolumia Obese or edematous images suboptimal
Areas not amnebale to compression
What are means of DVT prophylaxis peri-op?
Hydration and analgesia, early ambulation
Passive exerises in immobile
Leg elevation
Mechanical methods
Graduated stockings,
intermittent pneumatic compression
pressure 35-55 mmHg
pharma
What are CI to use of DVT prophylaxis?
bleeding disorders
hemophilia, thrombocytopenia <70
active/recent bleeding
eso varices
peptic ulcer
INB, GI bleed within 3months
precuation
liver, renal fialure
multiple truama
spinal/optho surgery
How does heparin work?
binds to enzyme inhibitor ATIII causing activation
inactivates thrombin and Xa
What are difference in unfractionated and LMW Heparin (fragmin)?
heparin vs LWMH
>daltons vs HIT 5% vs <HIT
reversed with protamine vs not easily reversed
IV and S/C vs S/C
How does warfarin work?
What is duration of action?
antagonizes vit K1 recycling, depleting active vit K1.
inhibiting synthesis of vit k dependent clotting factors
X, IX, II, VII (1927)
2-5 days
What is fondaparinox?
factor Xa inhibitor by causing conformational change in AT
no thrombocytopenia
What are examples of direct thrombin inhibitors?
What are they used for?
hirudin, argatrobanm, dabigatran
treatment of HIT
What is rivaroxaban?
direct oral factor Xa inhibitor
What is prophy dose of Uheparin, fragmin?
5000units bid or tid
2500-5000units OD
What are DVT pophy regimen?
ver low risk--agressive and early mobilization low risk--mechanical prophy (IPC) mod risk--heparin +/_stokcing/IPC high risk--high does heparin stocking/IPC
What are low and high risk procedures for DVT?
lap chole, appendectomy, prostatectomy, inguinal hernia repair, mastectomy
bariatric, cancer, neuro, TKR, THR, fractured hip
What is treatment for DVT?
elevation of leg and ambulation
anticoagulation
warfarin for 3 months or beyond if high risk
prevent recurrence/extension
bleeding risk 1-3%
stockings likely reduced PTS
What are the deep veins of the leg? arm?
iliac, femoral, popliteal, tibial
brachial, axillary, subclavian
What is the rational for surgical thrombus removal?
Rational for thrombus removal
Venous patency restored, valve function maintained, QOL improved, risk of recurrence reduced
Decreased comparment pressure with clot removal
What is the evidence for iliofem thrombectomy?
RCT for ilifem thrombectomy showed better vein patency, lower venous pressure, less edema and less Post thrombotic symptoms (all signif)
Observational study for iliofem, ctheter directed thormbolysis showed improved QOL
RCT for CDT
Improved venous patency and reduction in valvular incompetence
CaVenT trial Iliofem patency 6 months and PTS 2 years Alteplase 0.01mg/kg/hr max 96 hours Less PTS and better iliofem patency Bleeding complications 3.3% NNT to prevent one PTS is 7 (but not all patients in trial had iliofem dvt so maybe higher)
How does thrombus form?
Glu-plasminogen binds to fibrin which converts to ley-plasminogen. This produces more binding sites for plasminogen activators and more efficient production of plasmin. Thrombolysis occurs with the activation of fibrin bound plasminogen to plasmin
What is the dose of alteplase for infusion? intraop bolus?
10mg cathflo in 250ml NS
infuse 1mg/hr x 8hours then 0,5mg/hr until repeat angio
max dose 20mg/24hr
max duration 96hours
6-10mg bolus at 1mg/ml
What are benefits of intra-thrombus delivery of alteplase?
Less systemic circulation
Protects plasminogen activators from circulating plasminogen activator inhibitor
Protects the active enzyme plasmin from neutralization by circulating antiplasmin
What is success rate of CDT? complication rate?
80-90%
bleeding 5-10 ICH rare
What are some pharmacomechanical devices for DVT?
Amplatz
Angiojet
Treotola
Oasis
What are principles of surgical thrombectomy 6?
identify cause define extent prevent PE complete thrombectomy ensure unobstructed inflow and outflow prevent recurrence
Describe surgical procedure for venous thrombectomy?
For infrainguinal thrombus, elevated and compress the leg with rubber bandage, dorsiflex foot and calf and thigh squeezed
If persists then cutdown on post tib vein and advance fogarty from this direction
Can also use saline to flush from post tib end
Iliofem then performed with 8-10 balloon
Can use ballon occlusion from contralateral limb to prevent distal embolization
create AVF
IVC filter if thrombus in IVC
What are principles of AVF in venous thrombectomy?
Then create a small AVF at amputated end of the proximal saphenous. Limited to 3.5-4 mmm, increased venous velocity but not venous pressure
No increase in pressure should be recorded with open avf, if it does then the AVF is constricted
What are the AHA guidelines for managmeent of DVT?
Low risk of bleeding patient may be selected for CDT or pharmacomechanical CDT as first line treatmenet to prevent PTS
Surgical venous thrombectomy considered if iliofem thrombus (IIb)
How do you define MAssive PE?
Massive PE defined by systemic hypotension (40mmhg, syncope or cardiac arrest.
What are ideal features for IVC filter design? 8
Non thrombogenic material Self centering Secure fixation No impendence to flow Single trapping level and conical design (highest filtering to flow volume ratio Retrievable Visibility on imaging Cheap
What are evidence-based indications for IVC filter?
VTE CI to anticoag
VTE with complications of anticoag
recurr PE on anticoag
VTE inability to achieve therapeutic anticoag
What are expanded indications for IVC filter?
poor compliance free-floating ilio-caval RCC with renal vein extension VTE with limited CP reserve VTE in cancer, burn, pregnant patient cord injury trauma patients known hypercoag
What are CI for IVC filter?
chronically occluded cava vena cava anomalies inability to access cava vena cava compression no location for placement
What are complications of filter placement?
PE access site thrombosis filter migration cava penetration cava obstruction filter fracture guide wire entrapement
What are anomalies of the IVC complicating filter placement?
IVC transposition, duplication, agenesis
What is IVC transposition?
Left sided IVC drains into the left renal vein which crosses to the right and continues in normal direction. Suprarenal filter placement
What is IVC agenesis?
Absence of infraarenal segment
Azygos drainage. Place filter here
What is IVC duplication?
Right sided IVC drains the right iliac vein and right renal vein
The left sided ivc is susally smaller, drains left iliac vein, and joins left renal vein where it crosses over into the right sided vena cava
Place filter in each cava
When and how to place suprerenal filter?
thrombus in IVC, malpositionned in infrarenal, duplicate IVC, ovarian vein thrombosis, pregnancy
plae above highest renal so hooks not in RV
What is superficial thrombophlebitits?
Superficial thrombophlebitis or superficial vein thrombosis with phlebitis is a condition where superficial veins thrombose or clot can cause inflammation and induration (hardening, thickening) of the overlying skin.
Where is STP most common?
SV and tributaries
GSV >SSV
What are RF for STP?
endothelial injury, varicosities (most common), neoplasm, SLE, vasculitis
What organism cause suppurative TP?
s.aureua, pseudomonas, klebsiella, enterococcus, candida
What is incidence of STP after EVLT?
11%
How to diagnose STP?
Pain, erythema, tenderness or induration
DUS
What is tx for STP?
NSAIDS
topical liposomal heparin
What is the benefit of thrombolysis for DVT?
more complete clot resolution
preserved valve function
higher bleeding then heparin alone
How does cancer cause thrombosis at cellular level?
Tumor cells can express TF
TF binds to VII and initiates X and XI leading to thrombin generation
Cancer pro coagulant directly activates X
