DEEP VEIN THROMBOSIS (DVT)

What can be used to to effectively diagnose the presence of acute or chronic venous thrombosis in the veins.
Duplex Sonography
is Duplex sonography a reliable method of determining the extent of chronic venous disease? yes/no
yes
What is the most common reason for the clinical evaluation of the extremity veins?
Suspected deep venous thrombosis (DVT)-
What is the estimation of annual incidence of DVT in the United States ?
over 2.5 million cases.
The % of untreated patients with DVT will sustain a nonfatal PE is?
About 25%
PE is associated with a mortality rate of approximately 30%. with or without treatment
without treatment
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when was the first susceptibility to develop venous thrombosis was described ?
in 1865
Virchow’s triad consists of
Venous stasis
Endothelial damage
Hypercoagulability
See picture in slide 4
Thrombogenesis
the formation of a thrombus.
what does Inherited prothrombotic- do?
describes any agent or condition that leads to thrombosis) states have increased in frequency over the past 20 years.
This category of venous thrombosis is considered nonreversible
Inherited prothrombotic-
Clinical conditions that influence venous thrombosis
1,Inherited prothrombotic-
2,Antithrombin III deficiency
3,Pregnancy and the postpartum period-
4,Oral contraceptives and hormone replacement therapy-
5,Antiphospholipid antibody syndrome-
6,Protein C and protein S are vitamin K-dependent-
7,Factor V Leiden-
What category was the first reported congenital thrombotic condition
Antithrombin III deficiency
Isolated spontaneous thrombosis has been described with this condition
Precipitating circumstances:
Trauma
Pregnancy
Surgical procedures
Antithrombin III deficiency
It is transmitted in an autosomal dominant (a pattern of inheritance in which an affected individual has one copy of a mutant gene and one normal gene on a pair of autosomal chromosomes
Pregnancy and the postpartum period- lower or higher
higher risk for developing DVT than the nonpregnant state.
what is a leading cause of maternal death after childbirth.
PE (1 fatal PE per 100,000 births)
what can increase the risk for DVT in premenopausal and postmenopausal women?
Oral contraceptives and hormone replacement therapy-
(The prevalence of DVT in women receiving oral contraceptives of 1 to 3 in 10,000)
Antiphospholipid antibody syndrome- refers to?
it refers to the presence of either the lupus anticoagulant antibody or anticardiolipin antibodies.
Protein C and protein S are vitamin K-dependent-
Protein C or S deficiency results in a sevenfold increased risk for developing venous thrombosis ( see picture slide 10)
What is Factor V Leiden- ?
blood clotting disorder.
most common inherited hypercoagulable condition.
present in 12% to 33% of patients with spontaneous DVT .
protein that is needed for blood to clot properly.
The different gene that makes the Factor V Leiden protein is inherited from one or both parents. True or False
True
The Factor V Leiden protein is harder to “turn off” or Turn on than the normal Factor V protein. This makes blood clots more likely to form, a condition called thrombophilia.
Turn off
Insufficient clotting power leads to bleeding problems.
Too much clotting power can lead to the formation of blood clots. True or False
True
A blood test (called a screening test)
can reveal Activated Protein C resistance. Another blood test that examines the genes (called DNA) will be done to find out if Factor V Leiden is the cause of the resistance and what type of Factor V Leiden a person has.
Acquired Risk Factors for DVT
Age (greater risk w/older age)
Immobilization
Surgery within 3 months
Stroke, paralysis of extremities
History of DVT
Cancer/Malignancy
Obesity
Female
Central venous catheters
Estrogen replacement
Oral contraception
Pregnancy
When does Antiphospholipid syndrome occur?
occurs when the immune system mistakenly attacks some of the normal proteins in the blood
Myeloproliferative disorders
group of diseases in which the bone marrow produces too many red blood cells, white blood cells, or platelets).
Nephrotic syndrome
is a condition that is often caused by any of a group of diseases that damage the kidneys’ filtering system.
(Inflammatory bowel disease ,Sickle cell anemia ,Marked leukocytosis in acute leukemia )
Well’s score
It is a useful guide in determining the need to perform a venous ultrasound.
Active cancer
patient receiving treatment for cancer within the previous 6 months or currently receiving palliative treatment). +1
Paralysis, paresis
or recent plaster immobilization of the lower extremities. +1
Recently bedridden
for 3 days or more or major surgery within the previous 12 weeks requiring general or regional anesthesia. +1
Localized tenderness
along the distribution of the deep venous system. +1
Poor visualization due to:
Obesity
Edema
Open wounds, limiting the area of insonation.
Things that can’t be removed that prohibits scanning of the area
Casts
Unna boots
Mechanisms of DVT
The balance between coagulation and anticoagulation is disrupted
Coagulation:
Anticoagulation:
blood sticks together to prevent excessive bleeding after an injury.
prevents spontaneous clotting.
Venous endothelial layers are antithrombotic
When there is an injury to the vessel wall leukocytes (WBC’s) attach to the walls.
Prothrombin (plasma protein) is activated. It converts prothrombin to thrombin.
Thrombin converts fibrinogen to fibrin threads and it forms a clot.
see picture slide 21
Non-movement of blood flow (stasis)
allows the blood to coagulate.
Platelets become trapped behind the valve cusps due to flow recirculation
Platelets can stick to the collagen layer of the venous wall and may accumulate
Cancer patients have an increased activation of blood coagulation as a result of a decrease in blood inhibitors (protein C or S). True or False
True
DVT in pregnancy can be contributed to:
The weight of the baby decreasing the venous outflow
Estrogen (replacement therapy or contraceptives) alters the state of coagulation.
After a thrombus is formed it can
Stabilize, Propagate, Shed/Embolize
Stabilize
The thrombus can stick to the vessel wall without changing from the current location in the vessel. This is the best course of action.
Propagate
The thrombus can grow or move to another location.
Shed/Embolize
A portion or all of the thrombus can break free and travel in the vascular system.
What are the common sites for DVT?
-Deep veins ( CFV, FV, Prof, Pop, Peroneal, PTV, Iliac veins).
-Superficial veins (GSV, LSV)
-Muscular veins (gastrocnemius and soleal sinus)
Perforators
-Valve sites
-Venous confluences (bifurcations).
DVT and patient history?
-Acute onset swelling
-Acute onset pain
-Persistent leg swelling
-SOB
-Previous DVT
-Clotting issues
DVT and Physical Examination
-Edema
-Tenderness
-Redness/warmth
-Varicose veins
-Hyperpigmentation (hard areas)
-Ulceration
What is the substance produced why the clotting system is activated?
-Thrombin
What is the main functions of thrombin?
-Convert clotting protein, fibrinogen to fibrin
-Activate the body’s own clot dissolving (“fibrinolytic”) system.
What form the basis of clots?
-Protein strands, formed from collection of fibrin molecules
True or False
When the body’s clot dissolving system starts to dissolve the clot, It leads to the production of fibrin fragments
-True
What is another name for fibrin fragments
d-Dimers
What are some factors that can increase d-Dimers?
-Infection
-Inflammation
-Pregnancy
True or False
Negative (normal) d-Dimer result, that almost rules out the possibility that the patient doesn’t have a blood clot actively forming
False
-negative (normal) d-Dimer result, that almost rules out the possibility that they have a blood clot actively forming
What do an elevated d-Dimers test means?
Elevated d-Dimer result means that additional testing may be needed to see if a blood clot exists. It does not mean the patient has a blood clot
What is the first-line assessment of patients suspected of suffering VTE, PE, or DVT?
d-Dimer test
What is the different arterial and venous imaging?
-Arterial imaging help to determine how narrow is the vein
-Venous imaging help to determine presence or absence of thrombus (Chronic or Acute)
What are the main goal of diagnosing venous thrombosis?
-Presence or absence of thrombus.
-The relative risk for the thrombus dislodging and traveling to the lung.
What are the three kinds of veins that will be examined by duplex imaging?
-Deep veins
-Superficial veins
-Perforator veins
What is the main job of deep veins?
-To act as the main conduits that transport blood back to the heart.
True or False
Clots within the superficial veins are more likely to produce a clinically significant pulmonary embolism because these clots are usually larger than those in the deep system
False
Clots within the deep veins are more likely to produce a clinically significant pulmonary embolism because these clots are usually larger than those in the superficial system
True or False
Because they are surrounded by muscle, the chance of the clot being dislodged during muscle contraction is higher than for a clot in the superficial veins.
True
What is the main focus in a lower extremity venous duplex examination?
-The deep system
True or False
Their job is to be the primary source for returning blood to the heart
False
Their job is not to be the primary source for returning blood to the heart
What is the main job of superficial veins?
-Get blood close to the skin surface so the veins can help to regulate body temperature
True or False
When the body needs to cool down, they enlarge to shunt large amounts of warm blood to the skin so that heat escapes the body.
True
Why clots in the superficial system are less likely to cause major, clinically significant pulmonary embolism?
Because they are usually smaller than clots found in the deep veins, and they are less likely to be dislodged because they are not surrounded by muscle
True of False
Examination of the superficial veins is still an important part of a complete evaluation of the lower extremity.
True
True or False
There is also potential danger that a superficial vein clot can extend into the deep system.
True
What is the main job of perforator veins?
-Their job is to keep blood moving from the superficial system into the deep system.
What can happen perforator work well, and when they do not work properly?
-When they are working properly, they keep blood from pooling at the level of the skin.

-When they do not function, blood can pool at the skin level and chronic stasis changes and even ulcers may result.

Once thrombus has been identified, What should be the next step?
-Try to gain some information about how fixed or poorly attached the clot is and the likelihood of embolization.
True or False
The newer the clot, the more likely it is to embolize
True
What are the characteristics usually associated with acute clot?
– Faintly echogenic (hypoechoic) thrombus
– Poorly attached thrombus
– Spongy-texture thrombus
– Dilated vein (when totally obstructed)
What are the characteristics usually associated with chronic clot?
– Brightly echogenic (hyperechoic) thrombus
-Well-attached thrombus
-Rigid texture of thrombus
-Contracted vein (if totally obstructed)
-Large collaterals
-Thickened vein walls
True or False
When a thrombus has just formed, it is very faintly echogenic—almost invisible.
True
What the the most common scanning plane used for venous duplex examination?
Transverse plane
True or False
Transverse imaging should be performed with gray scale when performing venous duplex examination?
True
When does a vein is believed to be thrombus free?
When it compresses completely so that the inner vein walls actually touch each other.
True or False
If the “cuts” are too far apart, a major section of vein containing thrombus can be missed. As a rule, the smaller the cuts, the less chance there is of missing a thrombus.
True
What are some useful technics that help getting additional information regarding blood flow through the venous system?
-Rotate the probe and scan the segment in the longitudinal plane

-Add color and pulsed Doppler

True or False
Substituting longitudinal views with color Doppler for the transverse compression views will result in missing partially obstructive thrombus.
True
where is Thrombus is present?
Thrombus is present within the vein when echogenic material is identified within the lumen of the vein and when full compression of the vein is impeded
some institutions refer to duplex venous imaging as ….
“compression ultrasound”
Pitfalls
Incomplete compression from a patient bearing down in response to painful probe compressions

Compression being limited by a nearby bone, and other factors.
In the case where the vein is not compressing, but thrombus cannot be seen directly (poor views or views of very small or deep structures).

Failure of the venous valve mechanism causes venous reflux and prolonged residence time of deoxygenated blood in the lower extremity, especially in the standing position. True or False
True
Venous obstruction, venous reflux, or both in combination manifest clinically as chronic leg
swelling, ankle pigmentation, and, ultimately, ankle ulceration in the “gaiter zone,” just above the ankle. This is known as the postthrombotic syndrome.
Where is the gaiter zone located ?
it is located in the lower calf and ankle. In this region, the ambulatory superficial venous pressures are the highest, leading to edema, pigmentation, and ultimately, ulceration
Anticoagulation therapy
Heparin
Warfarin (Coumadin
Anticoagulation is ?
The first step in stable patients with pulmonary embolism
Warfarin
is the drug of choice for anti-coagulation.
It is taken by mouth beginning immediately upon the diagnosis of pulmonary embolism, but may take up to week for the blood to be appropriately thinned or anticoagulated
Heparin?
it is used to decrease the clotting ability of the blood and help prevent clots from forming in blood vessels.
INR or international normalized ratio
is the blood test used to monitor warfarin therapy. see slide 70
How is the ratio determined?
The ratio is determined by measuring the patients prothrombin time (test of blood thinness). This value is divided by the lab standard normal value.
Surgical Treatment
IVC filter
Iliofemoral venous thrombectomy
Bypass grafting
Surgical ligation/excision/bypass
see slide 71
Endovascular treatment
Balloon venoplasty (caval occlusion), it is used to open clogged vessels.
Mechanical thrombectomy-
-Angiojet for acute DVT
Venogram (phlebography or ascending phlebography
is a procedure in which an x-ray of the veins, dye is injected into the veins.

The dye has to be injected constantly via a catheter, making it an invasive procedure. Normally the catheter is inserted by the groin and moved to the appropriate site by navigating through the vascular system.

Contrast venography
is the gold standard for judging diagnostic imaging methods for deep venous thrombosis; although, because of its cost, invasiveness, and other limitations this test is rarely performed
Magnetic resonance imaging (MRI)
is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within the body.
A computerized tomography scan
CT scan, is a type of X-ray that uses a computer to make cross-sectional images of the body.
CT angiography
is a type of medical exam that combines a CT scan with an injection of a special dye called contrast material to produce pictures of blood vessels and tissues in a part of your body. The contrast is injected through an intravenous (IV) line started in your arm or hand.