Chronic Venous Pathophysiology Flashcards
What is chronic venous dx mainly due to?
Failure of function rather then obstruction
What are the most common cases of chronic dysfunction?
Reflux through failed veins which can involve the superficial and/or deep systems
What are other symptoms that some patients have with chronic venous dx?
Post-thrombotic symptoms
What does chronic venous disease include? (3)
- Post-thrombotic syndrome
- Reflux (venous insufficiency)
- Primary and secondary varicose veins
What are the symptoms of chronic venous insufficiency? (8)
Swelling/edema (pitting edema) Heaviness/ache Discolouration/ hyperpigmentation/ brawny discolouration Ulcers- mild pain Varicosities Venous claudication/ intense burning or cramping in calf Stasis dermatitis/dry, flakey skin Increased venous pressure
What causes pitting edema?
Venous hypertension or ambulatory hypertension
What are the 2 medical treatment for a chronic DVT?
- Injection sclerotherapy
2. Controlling the risk factors
What is injection sclerotherapy?
For small varicose veins sodium tetradecyl sulfate is injected into the varix which causes obliteration of the lumen
What are some risk factors that can be controlled?
Limiting long periods of inactivity
Promote venous drainage: compression stockings, elevating legs, unna boots, reducing weight on calf compression pumps during or after surgery
What are the surgical treatments for chronic DVTs?
- Ligation
- Vein stripping
- Venous ablation
What does the surgical treatments of ligation involve?
Ligation of incompetent superficial veins
Valvular reconstruction or valve transplantation
What is the endovascular treatment for chronic DVTs?
- Radio frequency ablation
- Trans illuminated power phlebectomy (TIPP)
- Laser-Thermal ablation
Who exclusively refers to the term post-thrombotic syndrome?
Pts who have previously experienced DVTs
What term is used for pts with similar symptoms as a DVT without previous history?
Chronic venous insufficiency (CVI)
Do fibrous strands remain after resolution of a DVT?
Yes
Is fibrous material a risk for embolization?
No
Does fibrous material create a site that is predisposed to recurrent acute DVT?
Yes
What occurs to the flow as a result of recannalization?
Produces irregular flow surfaces that impede flow
How does damage to the vessels affect the integrity of the venous valves from a chronic DVT?
Causes thickening, scarring and shortening of the leaflets
What can happen to the valves when they are thickened, scarred and have shortened of the leaflets?
Reflux
Explain the evolution of a thrombus.
- Spontaneous lyse- small thrombi lyse over in a short period of time due to natural fibrinolytic activity
- Propagation or embolization (acute state)
- Recannalization over time- fibrin strands produce irregular channels or scarred valve cusps
- Permanent occlusion- thrombus retracts causing vein to shrink into a fibrous cord (hard to visualize)
What causes reflux in the veins of the LE?
Absent or incompetent valves
What can lead to or cause venous hypertension?
Failed valves- allow full gravitational/hydrostatic pressure exerted on the vein walls
Calf muscle pump ineffective- decreasing ejection of blood resulting in increased residual venous volume
Failure of perforating veins- allowing flow to reverse from deep to superficial veins
What are some symptoms when flow is reversed within the perforators?
Heaviness and aching
What are varicose veins?
Veins that are palpable, distended and greater then 4mm in diameter
Describe PRIMARY varicose veins
Dilated tortuous veins that may be hereditary (congenital absence of valves) and restricted to the superficial system
Increased intraluminal pressure due to pregnancy, obesity and prolonged standing
Do pts with primary varicose veins have a favourable outcome?
Yes
What is the treatment for primary varicose veins?
Surgical ligation
What causes the development of secondary varicose veins?
Obstructive conditions such as previous DVT (damage to valves)
What is the appropriate therapy for secondary varicose veins?
Support stockings
What is the treatment for secondary varicose veins?
Surgical ligation of the perforators
What are the skin changes specific to chronic insufficiency?
Edema- due to increase venous pressure
Brawny discolouration- result of leakage of RBCs into surrounding tissue
Ulceration
Redness/rubor-itis/cellulitis
Does secondary varicose veins include the superficial or deep systems?
Both systems
What does testing with a CW Doppler probe determine?
Presence and origin of reflux
What other veins are assessed with the CW Doppler probe?
GSV, SSV and perforators
What are the factors evaluated in acute dx using CW Doppler?
Spontaneity, phasicity and response to distal and proximal compressions
What is the factor evaluated in chronic dx using CW Doppler?
Valve competency
What is the evaluation of CW based on?
Evaluation of auditory signals in the resting position
Comparison to the signal received after manual compressions or valsalva maneuvers or rapid cuff deflation
Does CW show a picture?
No
What does color duplex Doppler demonstrate?
Reflux using valsalva and compression techniques
What is the perfered position the pt be in when examining with color duplex Doppler?
Standing
What allows for visualization of specific sites with the ability to collect flow velocity data?
Color duplex
How long does it take a normal valve to close?
0.5 sec
Should there be flow reversal seen with proximal compression or valsalva maneuver?
Minimal to no flow reversal seen
How should the pt be positioned with complete proximal compressions?
Supine
What is distal augmentation used for?
Looks for reversed flow immediately following release of squeeze
What type of Doppler is used to best interrogate perforator veins?
Color Doppler
What is the normal caliber of perforator veins?
<3mm
Abnormal perforators will have bi-directional flow and a lumen diameter of what?
<4mm
What are some limitations of the color duplex exam?
Obesity, pitting edema, bony structures, casts and bandages
Is it common for there to be complete recannalization with restoration of flow?
Yes
What may the only indication of a previous DVT be?
Minimal valvular incompetence
What can happen when echogenic material is left in the lumen vessel?
Incompressibility
How do the echos appear within the vein the longer the chronic obstruction or partial residual fibrin deposits exist?
Brighter and stronger echos are seen in the vein
Is the presence of fibrin strands seen within the vein?
May be seen
Is the development of CVI and post-thrombotic symptoms such as ulcers and skin changes seen in the UE?
Rare to be seen in the UE
What type of US mode is used when there is uncertainty as to the availability of superficial veins for the use of bypass conduits?
Duplex US
What is the most common use for preoperative venous mapping?
CABG and LE grafts
What are the advantages for preoperative assessment?
Documentation of length, diameter, branching, and anomalies before procedure
What veins are considered suitable for harvest?
When the diameter is greater then 2.5mm
Why are the autologous (native) veins the conduit of choice for bypass procedures?
Due to long term patency and greater durability rather then prosthetic materials
What is the first choice of veins for surgeons for bypass procedures?
GSV
Why is the GSV the first choice for surgeons when preforming bypass procedures?
Excellent length and dimensional features
When evaluating the GSV, how should the pt be positioned?
1st choice is standing
2nd choice reverse trendelenburg position at 30deg with leg fully externally rotated and knee flexed
Why should the pt be kept warm when scanning their leg?
To keep veins dilated
What type if probe is used for preoperative scanning?
10MHz
What other vessels are evaluated for preoperative scanning?
SSV, femoral vein and basilic and cephalic of the UE
What is the preoperative vessels assessed for?
Anatomic variants, structural abnormalities, wall thickening, varicosities and valvular incompetence
When are diameter measurements taken within the vein?
Obtained at intervals along vein
What is done when the vein has a borderline diameter?
The pt must stand and be remeasured with a tourniquet to obtain max distension
In the case of a in-situ graft, can US be used to identify the valves allowing lysis under angioscopic guidance?
Yes