Chap 49 DVT Flashcards by Christine Herman

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

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What % of sympto DVT have PE?

50%

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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%

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What are features of DVT on DUS?

Absence of spontaneous flow
Absence of flow augmentation
Visible thrombus
Absence of compressability
Absence respiratory phasicity

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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

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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

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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

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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

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How does heparin work?

binds to enzyme inhibitor ATIII causing activation

inactivates thrombin and Xa

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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

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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

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What is fondaparinox?

factor Xa inhibitor by causing conformational change in AT

no thrombocytopenia

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What are examples of direct thrombin inhibitors?

What are they used for?

hirudin, argatrobanm, dabigatran

treatment of HIT

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What is rivaroxaban?

direct oral factor Xa inhibitor

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What is prophy dose of Uheparin, fragmin?

5000units bid or tid

2500-5000units OD

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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

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What are low and high risk procedures for DVT?

lap chole, appendectomy, prostatectomy, inguinal hernia repair, mastectomy

bariatric, cancer, neuro, TKR, THR, fractured hip

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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

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What are the deep veins of the leg? arm?

iliac, femoral, popliteal, tibial

brachial, axillary, subclavian

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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

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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