Venous & Lymphatic Flashcards
What is the definition of varicose veins?
Subcutaneous veins that dilate >= 3 mm when upright
What pressure compression stockings should you prescribe for venous ulcers?
30-40mm Hg (ESCHAR trial)
Which artery runs between the GSV and deep femoral vein?
External pudental artery
What was the main conclusion of the ESCHAR trial?
Surgical group had same rate of healing as medical group but lower venous ulcer recurrence
What is the recurrence rate of SSV reflux after surgery?
Up to 60%
When is ligation and stripping indicated over EVLT?
Chronic thrombophlebitis w synechia, too superficial/extrafascial vein, acute superificial venous thrombosis, very tortuous, aneurysmal > 2.5 cm GSV
What are 5 indications for varicose vein surgery/intervention?
Symptomatic, reflux > 1 s + varicosity > 4mm, venous ulcer, significant hemorrhage, lipadermotasclerosis, failure of 6 month trial of compression
What is the caprini score?
Risk factor calculations for VTE - most widely used in US 2005
Name 10 risk factors for VTE?
1 - Older age (rare in children)
2 - Trauma
3 - Malignancy (20% of first time VTE)
4 - Immobility
5 - Surgery
6 - Travel (unclear actual risk - WHO)
7 - Previous hx of VTE (25% of acute DVT has previous hx)
8 - A Blood group
9 - Compression (May thurner/popliteal entrapment)
10 - SLE
What types of malignancies have the highest rates of VTE?
pancreatic - then kidney, ovary, lung, stomach
How do cancer cells initiate thrombus formation (3)
1 - via tissue factor - not normal present in resting endothelium but is activated by tumour cells. This binds factors 7 and 7a which activates 10 and 11 and eventually thrombin.
2- cancer procoagulant - direct X activator
3 - cytokines (e.g. VEGF, TNF alpha, IL-1) activate tissue factor
What are the most common coag abnormalities in patients with malignancy?
increased fibrinogen and thrombocytosis
Name 5 ways in which chemotherapy can increase risk of VTE
1 - use of central venous catheters
2 - tumour cell lysis
3 - direct endothelial injury
4 - induces hypercoagulable state
5 - reduced fibrinolytic activity
What type of surgical procedures are at highest risk of DVT?
ortho - hip/knee surgery up to 50% vs gen surg 20%
Where do pregnant women typically develop VTE?
Left leg (97%!) - uterine compression
Which coag factors are increased when pregnant women are in a transient hypercoag state?
2, 7, 8, 10, vWF, fibrinogen
What risk factors make women prone to getting DVT during pregnancy?
advanced age, thrombophiia history, suppression of lactation, assisted delivery
How does estrogen cause DVT e.g. OCP?
increases blood viscosity, fibrinogen, platelet activation and adherence, factors 7 and 10
Which blood type is higher risk of VTE?
A highest risk, O lowest
Does varicose veins increase risk of DVT?
Yes - depending on age. Young are at higher risk, old no difference. Varicose veins may be markers of previous DVT
What is May Thurner syndrome?
Left iliac vein compression by right iliac artery leading to venous outflow obstruction/venous hypertension
What is the recurrence rate of vte at 2, 5 and 10 years?
15%, 25%, 30%
What is the rate of post thrombotic syndrome after acute proximal DVT?
~50% within 2 years with CDT or anticoagulation (ATTRACT)
What did ESCHAR trial show?
No difference in ulcer healing with GSV stripping vs. compression stockings. Lower recurrence with stripping.
What percentage of leg thrombi resolve spontaneously? What percentage extend more proximally?
50%, 20%
When would you expect a DVT to recanalize?
Greatest changes first 3 months - 50% thrombus burden reduction
What are risk factors for developing post thrombotic syndrome?
Ipsilateral recurrent DVT is most important risk factor Also multisegment disease, proximal disease - iliac involvement, popliteal vein involvement
What are 5 symptoms on the Villalta score?
1- Pain
2 - heavyness
3- pruritis
4-cramps
5-paresthesias
What are the 7 clinical signs on the villalta score?
1-pretibial edema,
2 - skin induration
3 - venous ulcer present
4 - pain on calf compression
5 - redness
6 - venous ectasia
7 - Hyperpigmentation
What is the theoretical benefit of thrombolysis vs anticoagulation for acute DVT?
successful thrombolysis preserves endothelial function and valve competence in animal studies. worst post thrombotic syndrome results from obstruction and valve reflux.
What is the difference between primary and secondary upper arm DVT?
Primary - idiopathic or effort thrombosis e.g. Paget Schrotter
Secondary - cancer or indwelling catheter
What is the RIETE registry?
Largest prospective registry of all patients with DVT (upper and lower)
What is phlegmasia?
Consequence of severe DVT with venous outflow obstruction to the point of limb ischemia +/- limb loss
What is phlegmasia alba vs. cerulean? What’s worse?
Alba = milk leg - swollen white
Cerulean = cyanotic, worse than alba
How do catheter related DVTs present? Common presentations and rare?
1 - asymptomatic, on imaging
2 - common: red, pain, swelling of neck/chest/arm
3 - rare: tremendous engorgement of chest wall veins, phlegmasia
What percentage of patients with upper extremity DVT go on to have a PE?
5-20%
What type of patients are at higher risk of getting a PE after upper extremity DVT?
Cancer patients
Should you anticoagulate all patients with central venous catheters?
Even though at higher risk of DVT, no support for anticoagulation
What are 3 catheter-related risk factors (not patient related) for developing a DVT with indwelling catheter?
1 - duration of use
2 - multiple punctures required
3 - large diameter catheter
What are 4 patient related (not catheter related) risk factors for developing a DVT from indwelling catheter?
1 - infection
2-malignancy
3-inherited thrombotic disorder
4-previous DVT
What central line catheter tip position is recommended to reduce the risk of subsequent DVT?
Junction of right atrium and SVC (French guidelines)
What percentage of PICCs result in DVT?
3%
What central line access has highest risk of DVT? (IJ, subclavian, femoral)
Femoral. IJ=Subclavian equivalent thrombotic risk.
What do chest guidelines recommend with respect to catheter related upper extremity DVT?
3-6 months of anticoagulation and removal of the catheter
Which patients with upper extremity DVT may benefit from thrombectomy/thrombolysis (6 patient characteristics)?
Chest 2016 guidelines:
1- phlegmasia
2- severe symptoms,
3- thrombus in axillary or subclavian,
4- good functional status,
5- low risk of bleeding,
6 -life expectancy > 1 year
How many valves does the GSV have?
7-10
What percentage of patients have a duplicate GSV
15% (anterior accessory GSV most common)
What is a major tributairy to the small saphenous vein?
intersaphenous vein
What are 2 differences between telengectasias and reticular veins?
1) size - reticular 1-3mm, telengectasia 0.1-1mm
2) appearance - telengectasia are red or blue depending on origin, reticular veins involve lateral aspect of the leg (lateral subdermic venous system)
What CEAP class?
C0
What CEAP class?
C1 - telengectasias or reticular veins
What CEAP class?
C2 varicose veins > 3mm
What CEAP class?
C3 edema
What CEAP class?
C4a - pigmentation or eczema
What CEAP class?
C4 lipadodermatosclerosis
What CEAP class?
C5 healed venous ulcer
What CEAP class?
C6 active venous ulcer
What do the SVS and American Venous Forum recommend for treating chronic venous disease?
EVLT or RFA - similar efficacy, better than surgery in terms of recovery, morbidity and pain. Also better than foam sclerotherapy in terms of efficacy
How should you treat telengectasia and reticular veins?
Liquid or foam sclerotherapy
Which endovenous treatment involves destroying the endothelium, contraction of vein and collagen/thrombus formation?
RFA
What are 5 contraindications to RFA of veins?
1-SVT
2- DVT
3- ABI < 0.9
4 - venous aneurysm
5- pacemaker (not a strict contraindication)
Where should you park your RFA catheter?
2.5 cm distal to SFJ to avoid endothermal heat induced thrombosis or extension of thrombus to CFV.
What is tumescent anesthesia composed of?
50 mL lidocaine w epi, 450 mL saline, 10 mL or sodium bicarb
Why is tumsecenet anesthesia used for endovenous procedures? (2)
1 - pain relief
2 - buffer around the vein to protect the surrounding tissue
How much tumescent anesthesia can be used safely?
35 mg/kg
What are your 3 post-op instructions for the patient after RFA endovenous treatment?
1 - Wear compression stocking 30-40 mm Hg for 1 week
2 - Come back in 72 h for a duplex ultrasound to confirm no CFV thrombus extension
3 - ambulate to help seal the vein
What are 9 potential complications of endovenous treatment with RFA?
1-vessel perf
2 - thrombosis
3 - PE
4 - phlebitis
5- thrombus of CFV
6 - infection
7 - nerve injury
8 - skin discolouration
9 - skin burns
What wavelength range are available for EVLT?
810 to 1470 nm
What are the potential benefits of a high wavelength EVLT laser?
Less pain and bruising
What are the potential benefits of a jacket tibbed fiber compared with bare tipped fiber for EVLT?
less pain and bruising
What energy of EVLT are typically used?
50-80 J/cm
What are the advantages of higher energy LEED (linear endovenous energy density)? Disadvantages?
Pro: Better treatment effect.
Cons: More parasthesia and pain post-op
What is the risk of DVT following EVLT?
0-5%
What is the risk of skin burns with EVLT?
< 1%
What is the risk of superficial thrombophlebitis with EVLT
0-25%
What are 6 relative contraindications to sclerotherapy?
1 - asthma
2 - DM
3- hypercoagulable states
4 - leg edema
5 - advanced PAD
6 - Chronic renal insufficiency
What are 8 absolute contraindications to sclerotherapy?
- allergy
- acute cellulitis
- acute resp or skin disease
- severe systemic disease
- phlebitis migrans
- pregnancy
- hyperthyroid
- bedridden
What are 3 types of sclerosing agents?
1-osmotics
2-alcohols
3-detergents
What is the strongest and weakest types of sclerosing agents?
Strongest - detergent (sotradecol), weakest - alcohol (glycerin)
What type of sclerotherapy do you use for larger reticular veins and varicose veins?
Foam - bubbles have increased surface area and stay in contact with endothelium longer
How do you calculate the volume of foam to inject into veins?
V = π x (D/2) x L
V=volume
D = diameter
L = length
What type of sclerosing agents are the most painful to inject?
Hypertonic saline
Name 3 conditions associated with venous gangrene
- Cancer
- HITT
- Warfarin induced protein c deficiency
What does D-dimer measure?
DD is a product of proteolysis by plasmin, elevated levels signify fibrinolysis is occurring (e.g. response to injury)
What conditions other than DVT may elevate D dimer (4)
- Recent surgery/trauma
- Pregnancy
- Cancer
- Thrombotic disorders
When does the thrombus become adherent to vein wall? Why does this matter?
7-10 days, lower efficacy of systemic thrombolysis or thrombectomy
How should you treat an acute DVT associated with cancer?
3 months of anticoagulation with LMWH (better than vitamin K antagonist) - 2016 Chest guidelines
How long should you bridge warfarin with UFH for treating dvt? why do you need to?
4-5 days. Natural anticoagulants protein c & s are also inhibited by warfarin and have a shorter half life than other factors therefore warfarin is procoagulant for the first 3 days.
Which DOAC has less renal clearance and does not require renal dose adjustment for treating VTE?
Apixaban
What is the 4 year patency of iliac veins after venous thrombectomy with av fistula?
80%
What are 1 point items on the Caprini score (name at least 5)?
- Age 40-60
- Minor surgery
- Major surgery < 1 mo ago
- Varicose veins
- CHF
- Obesity
- Swollen
- Lung disease
- COPD
- Pregnant
What are risk factors worth 2 points on Caprini score?
- Age 60-75
- Arthroscopic surgery
- Malignancy
- Major surgery
- Laparoscopic surgery
- Confined to bed
- Immobilizing cast
- Central venous access
Name 5 risk factors on the Caprini score that are worth 3 points
- Age > 75
- Previous DVT
- Family history of VTE
- Factor V leiden
- SLE
- HIT
- Elevated homocysteine
Apart from improving venous hemodynamics, which factors do intermittent pneumatic compression stockings stimulate to protect from VTE?
tpA, prostacyclin, tissue factor pathway inhibitor
How does ASA work as a blood thinner (molecular)?
Acetylates irreversibly COX-1 which then inhibits platelet derived thromboxane A2
What is the mechanism of action of unfractionatedheparin?
Inactivates thrombin and factor Xa and reduces thrombin induced platelet activation
What is the mechanism of action of LMWH?
Xa inhibitor, also inhibits thrombin but to a lesser extent
What is virchow’s triad?
Factors that contribute to thrombosis: 1. Stasis 2. Endothelial injury 3. Hypercoagulable state
What is a normal standing resting venous pressure (mm Hg)
60-80 mm Hg
How much (in mm Hg) can you increase compression stocking strength before occluding lower extremity veins?
60 mm Hg
What are the four strengths (as in mm Hg) for compression stockings? Which strength do you need a prescription?
- 10-20 mm Hg (over the counter)
- 20-30 (prescription)
- 30-40 (prescription)
- 40-50 (prescription)
Name 5 medications that have been tried for treating chronic venous insufficiency. Do any of them work?
- Diuretics - controversial
- Pentoxyfiline
- Phlebotropic (Flavonoids) - best evidence that there may be benefit but not enough for formal recommendation
- Zinc
- Prostaglandins
What are 6 indications to treat incompetent perforator veins
Evidence about IPV role is lacking. Described indications include:
1) venous hypertension
2) prevention of advancement of CVI
3) symptomatic varicose veins
4) varicose vein recurrence
5) promotion of venous ulcer healing
6) preventing venous ulcer recurrence