Venous Disease Flashcards
(252 cards)
How to size iliac vein stents
Proper sizing is needed for iliac venous stenting to avoid the complication of migration. Stent migration to the right heart or the pulmonary artery is potentially lethal and requires advanced endovascular retrieval techniques. If these endovascular techniques are unsuccessful, then open surgery with stent extraction is required. Most key opinion leaders recommend oversizing the venous stent by 10% to 15% of the largest diameter of the normal adjacent vein.
Placement of iliac stents
Prior to the recent introduction of dedicated nitinol venous stents in the United States, the most frequently placed stent for iliac vein compression (thrombotic or nonthrombotic) was a closed cell braided stent. Although this stent has some desirable properties for venous stenting, such as adequate outward radial force, its placement can be imprecise. Precise placement at the iliocaval confluence can lead to distal stent collapse because the ends of the stent have the least outward radial force. It is recommended that this stent be extended into the inferior vena cava for several centimeters. This cranial extension can result in the stent covering or “jailing” the contralateral limb. Several authors have demonstrated an incidence of contralateral deep vein thrombosis of up to 10% when this stent is extended across the contralateral limb, which is significantly higher than in cases where the stent is not extended across the iliac confluence.
Nutcracker syndrome
Nutcracker syndrome is the compression of the left renal vein between the superior mesenteric artery and aorta, or the vertebral spine and aorta if there is a retro-aortic left renal vein. Hematuria can be either microscopic or macroscopic, and is the most common clinical feature of NCS, especially when there is left flank pain. Patients with abdominal pain secondary to NCS have left flank pain rather than right flank pain. Patients can have vulvar varices in addition to gluteal and lower extremity varicosities, but these are also seen with other venous disorders and are only possibly related to NCS. Dysuria and dysmenorrhea can occur with NCS but are less suggestive of the NCS than hematuria.
Indication for anticoagulation in SVT
Anticoagulation for patients with SVT should be considered for those at increased risk for thromboembolism and for those with recurrent superficial vein thrombosis. These include patients with positive medical risk factors for vein thrombosis, an affected vein segment ≥5 cm, and a thrombus in proximity to the deep venous system (≤5 cm). A significant reduction in the incidence of pulmonary embolism has not been consistently demonstrated. The largest placebo-controlled trial, CALISTO trial, randomly assigned 3,002 patients to receive fondaparinux (2.5 mg subcutaneous daily for 45 days) or placebo. Patients had duplex-confirmed thrombophlebitis over more than 5-cm length of vein. Significant reductions were seen in the incidence of thrombus extension (0.3 versus 3.4 percent), recurrence of phlebitis (0.3 versus 1.6 percent), and deep vein thrombosis (0.2 versus 1.2 percent).
Where should filter be placed in pregnancy
suprarenal- due to risk of compression in infra-renal filter by gravid uterus
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
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