DEEP VEIN THROMBOSIS (DVT) – Flashcards
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What can be used to to effectively diagnose the presence of acute or chronic venous thrombosis in the veins.
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Duplex Sonography
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is Duplex sonography a reliable method of determining the extent of chronic venous disease? yes/no
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yes
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What is the most common reason for the clinical evaluation of the extremity veins?
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Suspected deep venous thrombosis (DVT)-
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What is the estimation of annual incidence of DVT in the United States ?
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over 2.5 million cases.
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The % of untreated patients with DVT will sustain a nonfatal PE is?
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About 25%
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PE is associated with a mortality rate of approximately 30%. with or without treatment
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without treatment
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when was the first susceptibility to develop venous thrombosis was described ?
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in 1865
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Virchow's triad consists of
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Venous stasis Endothelial damage Hypercoagulability See picture in slide 4
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Thrombogenesis
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the formation of a thrombus.
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what does Inherited prothrombotic- do?
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describes any agent or condition that leads to thrombosis) states have increased in frequency over the past 20 years.
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This category of venous thrombosis is considered nonreversible
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Inherited prothrombotic-
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Clinical conditions that influence venous thrombosis
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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-
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What category was the first reported congenital thrombotic condition
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Antithrombin III deficiency
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Isolated spontaneous thrombosis has been described with this condition
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Precipitating circumstances: Trauma Pregnancy Surgical procedures
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Antithrombin III deficiency
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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
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Pregnancy and the postpartum period- lower or higher
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higher risk for developing DVT than the nonpregnant state.
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what is a leading cause of maternal death after childbirth.
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PE (1 fatal PE per 100,000 births)
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what can increase the risk for DVT in premenopausal and postmenopausal women?
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Oral contraceptives and hormone replacement therapy- (The prevalence of DVT in women receiving oral contraceptives of 1 to 3 in 10,000)
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Antiphospholipid antibody syndrome- refers to?
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it refers to the presence of either the lupus anticoagulant antibody or anticardiolipin antibodies.
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Protein C and protein S are vitamin K-dependent-
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Protein C or S deficiency results in a sevenfold increased risk for developing venous thrombosis ( see picture slide 10)
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What is Factor V Leiden- ?
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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.
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The different gene that makes the Factor V Leiden protein is inherited from one or both parents. True or False
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True
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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.
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Turn off
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Insufficient clotting power leads to bleeding problems. Too much clotting power can lead to the formation of blood clots. True or False
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True
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A blood test (called a screening test)
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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.
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Acquired Risk Factors for DVT
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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
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When does Antiphospholipid syndrome occur?
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occurs when the immune system mistakenly attacks some of the normal proteins in the blood
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Myeloproliferative disorders
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group of diseases in which the bone marrow produces too many red blood cells, white blood cells, or platelets).
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Nephrotic syndrome
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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 )
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Well's score
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It is a useful guide in determining the need to perform a venous ultrasound.
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Active cancer
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patient receiving treatment for cancer within the previous 6 months or currently receiving palliative treatment). +1
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Paralysis, paresis
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or recent plaster immobilization of the lower extremities. +1
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Recently bedridden
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for 3 days or more or major surgery within the previous 12 weeks requiring general or regional anesthesia. +1
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Localized tenderness
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along the distribution of the deep venous system. +1
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Poor visualization due to:
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Obesity Edema
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Open wounds, limiting the area of insonation. Things that can't be removed that prohibits scanning of the area
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Casts Unna boots
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Mechanisms of DVT
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The balance between coagulation and anticoagulation is disrupted
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Coagulation: Anticoagulation:
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blood sticks together to prevent excessive bleeding after an injury. prevents spontaneous clotting.
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Venous endothelial layers are antithrombotic
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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
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Non-movement of blood flow (stasis)
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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
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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
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True
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DVT in pregnancy can be contributed to:
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The weight of the baby decreasing the venous outflow Estrogen (replacement therapy or contraceptives) alters the state of coagulation.
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After a thrombus is formed it can
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Stabilize, Propagate, Shed/Embolize
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Stabilize
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The thrombus can stick to the vessel wall without changing from the current location in the vessel. This is the best course of action.
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Propagate
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The thrombus can grow or move to another location.
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Shed/Embolize
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A portion or all of the thrombus can break free and travel in the vascular system.
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What are the common sites for DVT?
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-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).
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DVT and patient history?
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-Acute onset swelling -Acute onset pain -Persistent leg swelling -SOB -Previous DVT -Clotting issues
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DVT and Physical Examination
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-Edema -Tenderness -Redness/warmth -Varicose veins -Hyperpigmentation (hard areas) -Ulceration
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What is the substance produced why the clotting system is activated?
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-Thrombin
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What is the main functions of thrombin?
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-Convert clotting protein, fibrinogen to fibrin -Activate the body's own clot dissolving ("fibrinolytic") system.
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What form the basis of clots?
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-Protein strands, formed from collection of fibrin molecules
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True or False When the body's clot dissolving system starts to dissolve the clot, It leads to the production of fibrin fragments
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-True
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What is another name for fibrin fragments
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d-Dimers
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What are some factors that can increase d-Dimers?
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-Infection -Inflammation -Pregnancy
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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
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False -negative (normal) d-Dimer result, that almost rules out the possibility that they have a blood clot actively forming
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What do an elevated d-Dimers test means?
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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
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What is the first-line assessment of patients suspected of suffering VTE, PE, or DVT?
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d-Dimer test
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What is the different arterial and venous imaging?
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-Arterial imaging help to determine how narrow is the vein -Venous imaging help to determine presence or absence of thrombus (Chronic or Acute)
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What are the main goal of diagnosing venous thrombosis?
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-Presence or absence of thrombus. -The relative risk for the thrombus dislodging and traveling to the lung.
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What are the three kinds of veins that will be examined by duplex imaging?
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-Deep veins -Superficial veins -Perforator veins
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What is the main job of deep veins?
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-To act as the main conduits that transport blood back to the heart.
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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
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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
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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.
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True
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What is the main focus in a lower extremity venous duplex examination?
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-The deep system
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True or False Their job is to be the primary source for returning blood to the heart
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False Their job is not to be the primary source for returning blood to the heart
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What is the main job of superficial veins?
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-Get blood close to the skin surface so the veins can help to regulate body temperature
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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.
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True
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Why clots in the superficial system are less likely to cause major, clinically significant pulmonary embolism?
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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
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True of False Examination of the superficial veins is still an important part of a complete evaluation of the lower extremity.
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True
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True or False There is also potential danger that a superficial vein clot can extend into the deep system.
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True
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What is the main job of perforator veins?
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-Their job is to keep blood moving from the superficial system into the deep system.
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What can happen perforator work well, and when they do not work properly?
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-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.
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Once thrombus has been identified, What should be the next step?
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-Try to gain some information about how fixed or poorly attached the clot is and the likelihood of embolization.
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True or False The newer the clot, the more likely it is to embolize
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True
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What are the characteristics usually associated with acute clot?
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- Faintly echogenic (hypoechoic) thrombus - Poorly attached thrombus - Spongy-texture thrombus - Dilated vein (when totally obstructed)
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What are the characteristics usually associated with chronic clot?
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- Brightly echogenic (hyperechoic) thrombus -Well-attached thrombus -Rigid texture of thrombus -Contracted vein (if totally obstructed) -Large collaterals -Thickened vein walls
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True or False When a thrombus has just formed, it is very faintly echogenic—almost invisible.
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True
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What the the most common scanning plane used for venous duplex examination?
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Transverse plane
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True or False Transverse imaging should be performed with gray scale when performing venous duplex examination?
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True
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When does a vein is believed to be thrombus free?
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When it compresses completely so that the inner vein walls actually touch each other.
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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.
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True
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What are some useful technics that help getting additional information regarding blood flow through the venous system?
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-Rotate the probe and scan the segment in the longitudinal plane -Add color and pulsed Doppler
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True or False Substituting longitudinal views with color Doppler for the transverse compression views will result in missing partially obstructive thrombus.
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True
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where is Thrombus is present?
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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
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some institutions refer to duplex venous imaging as ....
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"compression ultrasound"
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Pitfalls
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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).
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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
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True
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Venous obstruction, venous reflux, or both in combination manifest clinically as chronic leg
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swelling, ankle pigmentation, and, ultimately, ankle ulceration in the "gaiter zone," just above the ankle. This is known as the postthrombotic syndrome.
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Where is the gaiter zone located ?
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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
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Anticoagulation therapy
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Heparin Warfarin (Coumadin
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Anticoagulation is ?
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The first step in stable patients with pulmonary embolism
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Warfarin
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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
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Heparin?
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it is used to decrease the clotting ability of the blood and help prevent clots from forming in blood vessels.
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INR or international normalized ratio
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is the blood test used to monitor warfarin therapy. see slide 70
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How is the ratio determined?
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The ratio is determined by measuring the patients prothrombin time (test of blood thinness). This value is divided by the lab standard normal value.
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Surgical Treatment
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IVC filter Iliofemoral venous thrombectomy Bypass grafting Surgical ligation/excision/bypass see slide 71
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Endovascular treatment
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Balloon venoplasty (caval occlusion), it is used to open clogged vessels.
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Mechanical thrombectomy-
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-Angiojet for acute DVT
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Venogram (phlebography or ascending phlebography
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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.
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Contrast venography
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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
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Magnetic resonance imaging (MRI)
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is a technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues within the body.
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A computerized tomography scan
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CT scan, is a type of X-ray that uses a computer to make cross-sectional images of the body.
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CT angiography
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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.
