Deep vein thrombosis (dvt)

DEEP VEIN THROMBOSIS (DVT)
Deep vein thrombosis refers to clotting of blood in the deep veins, usually of the lower limbs. However, thrombosis can occur in upper limb veins, in the cerebral venous sinuses and in the veins in relation to the intestines, spleen and liver.
The risk increases with age, the difference being 1000-fold between childhood and old age.
What causes DVT?
DVT may occur spontaneously in some elderly people. In most other situations, there is
some occult or overt risk factor. There are 3 important factors that cause DVT: stasis of
blood, injury to vein wall and hypercoagulable state (increased tendency of blood to clot).
RISK FACTORS
Genetic (present in 40-60%): Deficiency of certain factors like protein C, protein S, antithrombin III, presence of factor V Leiden, abnormal prothrombin, hyperhomocysteinemia, hyperfibrinogenemia, abnormal fibrinolysis and high levels of factor VIII. These are not obvious and need to be looked for.
Most of the acquired risk factors are more obvious: major surgery, fracture of bone and use of plaster cast, trauma, pregnancy, puerperium, oral contraceptive pills, HIV positive status, acquired hyperhomocysteinemia, cancer, immobilization, previous episode of DVT and a debatable risk factor is long distance air travel.
Hospitalization is a very important risk factor for DVT. The incidence in
hospitalized population is 100 times that of general population.
Symptoms and signs
Most patients have swelling of the affected limb and pain. Presence of breathlessness indicates that part of the clot may have broken off and gone to the lungs. Diagnosis of DVT
Imaging is mandatory to make a diagnosis of DVT since a clinical diagnosis is like tossing a coin: one will be correct only half the times. Color Doppler is perhaps the best and most convenient imaging modality. One needs to evaluate all the veins of the affected limb including soleal & gastrocnemius veins.
A d-dimer assay is a very sensitive test and virtually rules out DVT if it is negative. It is useful as a screening test and in patients with recurrent DVT where color Doppler is not very reliable.
Investigations for pulmonary embolism include d-dimer assay, lung ventilation –perfusion scan, 2D echocardiography and spiral CT.
Investigations for hypercoagulable state:
These should be considered in young patients, when there is no obvious risk factor for
DVT, in patients with recurrent DVT and in patients with family history of thrombotic
disorders. Most investigations are inaccurate at the time of acute episode and while
patients are on anticoagulation. Ideally, patients should be investigated after the treatment
is over.
What are the problems that one may anticipate?
The disease has two major complications: pulmonary embolism and post- thrombotic syndrome and rarely, venous gangrene. Immediate problems can be due to the clot traveling to the lungs resulting in a potentially life-threatening situation called pulmonary embolism. Pulmonary embolism is seen in about 35-40% of patients with proximal DVT affecting the lower limbs. The majority of these patients have silent embolism. The incidence of PE from upper limbs is about 10-15%.
Rarely, extensive DVT can lead to venous gangrene and limb loss. In the long term, changes of chronic venous insufficiency can develop in the legs, resulting in swelling, eczema, black discoloration and ulceration. Once a person develops DVT, he or she is at higher risk for another episode in the presence of a risk factor, compared to a person who has not had DVT.
Can we prevent DVT?
While not entirely preventable, the incidence of DVT can be reduced significantly. Use of prophylaxis in the form of injections like Heparin and low molecular weight heparins, anti-embolism stockings and sequential compression devices can reduce the risk of DVT in patients exposed to any of the risk factors. It is worthwhile using travel stockings on long flights.
DVT prophylaxis: Should be used in all patients in medical or surgical intensive care units, in patients undergoing major surgery, hip or knee surgery, cancer surgery and surgical patients with risk factors for DVT.
Prophylaxis is recommended till the patient is bed-ridden and in some high risks situations for 6 weeks after surgery.
IVC filter: These may be temporary or permanent and prevent emboli from reaching the lungs. They can be positioned in the infrarenal or suprarenal IVC or in SVC depending on the requirement. The placement is done percutaneously under local anesthesia by the vascular surgeon.
Can we prevent complications of DVT?
Once DVT is detected, pulmonary embolism can be prevented by initiating adequate
treatment. In case of extensive DVT clot buster therapy or surgery may be necessary to
prevent venous gangrene. Changes of chronic venous insufficiency can be reduced by use
of graduated compression stockings.
How do we treat DVT?
Anticoagulation: Standard treatment consists of anticoagulation or blood-thinning
therapy. It is started with injections and then converted to tablets. In most cases, therapy
is continued for 6 months, occasionally for a year and rarely, life-long. The efficacy of
anticoagulation is monitored frequently with blood tests (prothrombin time and INR).
The INR is maintained between 2.0 & 3.0. Too much can cause bleeding while too little
can cause clotting.
Anticoagulation prevents further propagation of the clot and reduces risk of pulmonary
embolism. The clots usually do not dissolve completely. The residual clots can get
recanalized. In the process, some valves get destroyed and vein lumen may remain
occluded. It is important to use graduated compression stockings to reduce risk of chronic
venous insufficiency.
Thrombolysis: Also called clot-buster therapy, it dissolves the clot. A catheter is
threaded under radiographic control into the clot and the medicine is delivered into the
clot. It is very useful in extensive DVT where there is a risk of venous gangrene. Even in
other situations, complete dissolution of the clot may reduce the risk of long-term
complications of the legs by preserving normal venous valve function and normal vein
lumen. There is a small risk of bleeding with such therapy and it cannot be used in some
patients who have increased risk of bleeding due to recent surgery or trauma or peptic
ulcer. We now offer thrombolytic therapy to all patients with Iliofemoral DVT. This is a
catheter guided lytic therapy. The risk of embolism is minimal and a good lysis is likely
to reduce the risk of post-thrombotic syndrome.
Surgical thrombectomy: This is selected for the same reasons as thrombolysis in
patients who cannot receive thrombolytic therapy.
FAQs about treatment
How long should we treat?
First episode of DVT in patients with no obvious risk factor merits anticoagulation for 6
months. Recurrent DVT is treated for one year. In patients with uncorrectable
hypercoagulable states, life-long anticoagulation should be considered.
Do patients need bed rest?
Patients with DVT should be ambulated as soon as they can walk comfortably.
Is LMWH as effective as heparin?
Yes, and it is possibly more effective due to predictable bioavailability and anticoagulant
effect. It also offers the advantage of a better safety profile, no lab monitoring and
domiciliary treatment.
Role of stockings: All legs with DVT are wrapped with an elastic crepe bandage for the
initial few days. As the edema comes down, all patients are prescribed class 2 graduated
compression stockings. The stockings are worn throughout the day and removed at
bedtime. Patients are encouraged to walk with stockings. Use of stockings reduces the
risk of post-thrombotic syndrome by 50%.
DVT in pregnancy: LMWH and Heparin are safe. Oral anticoagulants can be used from
II trimester onwards in patients with mechanical heart valves but should be stopped
before term. LMWH and Warfarin are safe for nursing mothers.
IVC filters: IVC filters are basically wire meshes or cones or umbrellas that can be
positioned in the inferior vena cava (the major vein leading to the heart). A vascular
surgeon can place a filter within a few minutes under local anesthesia through a puncture
in the groin or neck vein.
Guidelines while on oral anticoagulant therapy
ACITROM / WARF is a blood thinning agent. Its effect needs to be monitored regularly with blood test: PT/INR. Overdosing can cause spontaneous minor or major or life-threatening bleed. Under-dosing will not treat your problem effectively.
Do not self-medicate since other medicines can affect the efficacy of this drug. Please inform your doctor about your disease and medication before taking any treatment, before any dental or surgical procedure.
Do not take any intramuscular injections. Do not take NSAIDS like brufen, voveran, piroxicam etc.
Inform your doctor in case of any obvious bleeding, breathing difficulty, black stools or alteration in sensorium.
You may continue on a normal diet unless specifically asked to change something.

Source: http://www.indiavascularsurgery.com/deep_%20vein_%20thrombosis_revised.pdf