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Written by Administrator
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Thursday, 08 October 2009 04:05 |
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A-Superficial Venous Thrombosis:
Causes:
1- Trauma of repeated injections.
2- Thrombophlebitis of varicose vein.
3- Phlebitis migrans which occurs in:
a) Buerger's disease. b) Septic foccus due to septic vasculitis.
c) Deep seated CA.(Bronchiogenic, Pancreatic, Gastric)
B- Deep Venous Thrombosis "D.V.T."
Predisposing Factors: Virchow's triad
1- Injury of endothelium of vein by infection or trauma.
2- Stagnation of blood by heart disease or prolonged recumbency.
3- blood viscosity by dehydration or polycythemia.
Predisposing Factors and high risk conditions:
1. Age above 40 espicially if obese and going to spend long time setting on chair e.g. long-haul air travel.
2. Prolonged recumbency in spine diseases or surgery.
3. Hip and knee replacement surgery.
4. Gynaecologic pelvic operations.
5. Prgnancy and labour especially if there is cysteinema and/or deficiency of antithrombin, protein C and protein S.
6. Contraceptive pills.
7. Patient with malignancy.
8. Patients under chemotherapy or radiotherapy.
9. Thrombophilia either genetic or acquired such as factor V Leiden, prothrombin 20210A mutation and antiphospholipid antibodies.
10. The most important risk factor is previous episode of DVT especially if the D-dimer level is still high reflecting ongoing thrombosis and fibrinolysis.
Pathology:
The thrombosis occurs in one of 2 forms:
A- Thrombophlebitis: Thrombosis due to inflammed veins.
Leads to adherent thrombus in the iliofemoral vein.
Associated Lymphangitis with arterial spasm Painful white (Phlegmasia alba dollens).
In sever (massive) cases severe limb congestion painful blue leg (Phlegmasia Cerrula dolens) gangrene (venous gangrene) which is usually superficial.
B- Phlebothrombosis: without inflammation "only stasis".
Leads to easily detached thrombus.
Start in the subsoleus veins if detached Pulmonary embolism.
Clinical picture
1- Oedema of the foot or leg. Loss of laxity of the calf when palpated which the knee is in moderate flexion.
2- Pain & tenderness in the sole or the calf.
3. Postoperative unexplained fever & tachycardia must direct the attention to the possibility of DVT.
4- Homan 's sign: Pain in the calf on dorsiflexion of the foot. It is painful and may induce pulmonary embolism by pushing the thrombus inside subsoleal vein plexus. So, better avoided.
Clinical types:
A) Iolated subsoleal plexus venous thrombosis.
B) Femoro-popliteal vein thrombosis.
C) Massive iliofemoral DVT.
Differential diagnosis:
DVT should be differentiated from all other causes of painful edematous leg:
1. Partial tear of tendo-achilis, it occurs usually during walking with typical history of sudden pain in the calf during activity. Bluish ecchymosis may appear later in 2-3 days. This diagnosis possibility should be excluded in any case to avoid worsening of the case if treated by heparin as DVT.
2. Post-traumatic calf haematoma.
3. Deep abscess or cellulites of the leg and foot.
4. Erysepilas of the leg and foot.
5. Complicated gastrocnemius bursae (Rupture, Hge., Infection).
6. Pelvic mass with compression or invasion of the iliac veins
Investigations:
1- Doppler ultrasound: Velocity detector when its probe put on femoral vein venous hum sound with continuous venous wave fluctuating with respiration. If the sound is absent this denotes complete venous occlusion. If the velocity is high with no or minimal fluctuation with respiration this denotes partial thrombosis of the iliofemoral segment.
2- Coloured Duplex Ultrasonography of the venous system: It is the best and least invasive investigation. It can give data about:
a. the actual site of the thrombus and its extent.
b. The condition of the thrombus and whether it is fixed to the wall or liable to detach.
c. Exclude other causes like pelvic masses, gastrocnemius bursae, calf abscess or haematoma.
The sensitivity of the duplex in proximal above knee DVT diagnosis is 98% with 95% specificity.
Ingection of the dye with tournequet closing superficial veins.
3- Contrast Venography: A well performed contrast venography still considered the gold standard for diagnosis of lower extremity DVT. Its use in modern practice is limited by cost, associated phlebitis and thrombosis and requirement of special training in catheter based technique. Its use now is limited to the following indications:
a. For delination of DVT prior to catheter based treatment of DVT.
b. A nondiagnostic ultrasound study.
c. Anticipated placement of a vena cava filter.
The ascending technique is the most commonly done with access via a superficial vein in the foot. If oedema prevents cannulation of the foot vein the popliteal or post. Tibial vein may be cannulated using ultrasound guidance.
A luminal filling defect with a surrounding rim of contrast is the classic venographic sign of venous thrombosis. Abrupt termination of the a contrast column especially if a meniscus is present. Failure to visualize an expected vein is not a reliable sign of venous thrombosis as the contrast may be passing through parallel deep or superficial vein.
4 - Magnetic resonance venography (MRV) can be done without contrast using phase contrast or time-of-flight techniques. Gadolinium can also be given intravenously with better accuracy in areas of slow flow or vessel tortuousity. In proximal veins it carries sensitivities of 100%. It is not useful for evaluating calf vein thrombosis. The technique is currently limited by high costs, limited availability.
5 - Computed Tomography Venography (CTV): can be done with no need to puncture the veins of the diseased limb. Its sensitivity in proximal vein is 90%. CT pulmonary angiography (CTPA) is the test of choice for evaluating pulmonary embolism so, CTV can be done after CTPA adding only few minutes. It carries the disadvantages of additional contrast over the required for just CTPA. The cost and poor accuracy for diagnosis of calf vein thrombi limits its use.
6 - Some alternative examinations such as plethysmography and fibrinogen labeling are of historic interest only.
Combined ultrasound clinical and laboratory assessment:
In addition to clinical assessment, duplex ultrasound has sensitivity above 95% in lesions above knee. In cases with infragenicular DVT with borderline duplex finding The D-dimer can be considered as indirect marker of DVT. The D-dimer is a fibrin specific degradation product that detects cross-linked fibrin resulting from endogenous fibrinolysis.
mTreatment:
I- Prophylactic measures:
a. Prophylactic heparin for patients in high risk. 5000 IU SC /12 hs.
b. Early postoperative ambulation.
c. Intra-operative limb massage by plastic cuffs connected to insufflations-deflation machine.
d. Intra-operative fixation of the feet to special machine which make continuous flexion and extension of the foot during operation.
II- Curative treatment:
(1) Complete bed rest with elevation of the limb while the Knee is in mild flexion for ten days or until fever & odema subside.
(2) Bandage over the whole limb for 2 - 4 weeks then elastic stock for 3-6 months.
(3) Anticoagulants:
A. Unfractionated Heparin: 400:800 units/Kg/day continuous infusion for ten days. Activated partial thromboplastin time can control the dose of heparin. It should not exceed double of the control value.
B. Fractionated Heparin: It carry better results than unfractionated heparin with lower risk of bleeding. It is given in subcutaneous route for 10 days.
C. Oral anticoagulant (Warfarin,Cumadin & Dendivan): It should be given with the appropriate dose according to the prothrombin time and concentration and International Normalizing Ratio (INR) of the patient at the time of diagnosis. The prothrombin concentration should be between 30-60% with INR between 2-3. The maintenance dose is given for 6 months.
(4) Thrmbolytic Therapy: The available thrombolytic drugs are Streptokinase, Urokinase or Tissue Plasminogen Activator(TPA). Systemic administration of theses drugs is relatively ineffective. Catheter directed technique provide the best results where the DVT is less than 10 days old. So it is used only for local thrmbolysis through venous catheter to the diseased vein aiming to dissolve thrombus and preserve valve function. Percutaeneous placement of stents after catheter thrombolysis may be needed to treat an underlying venous stenosis e.g. left iliac vein stenosis due to compression by the right iliac artery, the so called May- Thurner syndrome.
(5) Surgical removal of the thrombus and creation of AV fistula. It is done only in cases of severe iliofemoral DVT especially in young age.
Through inguinal incision the thrombus is extracted from iliac veins using Fogarty's catheter. "thrombectomy" and from femoral, popliteal and infrapopliteal veins by milking using rubber bandage (Ismarsh technique) .
(6) To Prevent spread of thrombosis or detachment of emboli into pulmonary artery. "pulmonary embolism".
Ø Thrombectomy if possible.
Ø Ligation of the femoral vein.
Ø Special filters can be percutaneously introduced into inf. vena cava.
SOURCE:DR AYMAN SALEM'S BOOK
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Last Updated on Friday, 09 October 2009 06:34 |
