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'''Associate Editor-In-Chief:''' {{CZ}}
'''Associate Editor-In-Chief:''' {{CZ}}


==Overview==


'''Thromboembolism''' is a general term describing both [[thrombosis]] and its main complication which is [[embolism]]
==Etymology==
The term was coined in 1848 by [[Rudolph Carl Virchow]].<ref>{{cite book|title=The Timetables of Science| first=Alexander| last=Hellemans| coauthors=Bryan Bunch| publisher=Simon and Schuster| location=New York, New York| year=1988| isbn=0671621300 |pages=317}}</ref>
==Incidence==
In the United States:
* 300,000–600,000 people have [[deep venous thrombosis]] ([[DVT]]) or [[pulmonary embolism]] ([[PE]]).
:* 200,000–400,000 people have [[deep venous thrombosis]].
::*Nearly one-third of people who have had [[deep venous thrombosis]] have post-thrombotic syndrome, a chronic disabling condition characterized by swelling, pain, discoloration, and scaling in the affected limb.
:* 100,000–200,000 people have a [[pulmonary embolism]].
::*Nearly one-third of people (30,000–60,000) who have a [[pulmonary embolism]] die.
* 5-8% of people have [[thrombophilia]] (inherited blood clotting disorders).
==Demographics==
==Diagnosis==
===Electrocardiography===
* [[Sinus tachycardia]]
* [[Right axis deviation]]
* [[Right bundle branch block]]
* Deep and inverted [[T wave]]s in V<sub>1</sub> - V<sub>3</sub>
* S<sub>1</sub>Q<sub>3</sub>T<sub>3</sub> pattern
<gallery>
Image:Pulm embolism.jpg|ECG of a patient with pulmonary embolism <small>Image courtesy of [http://www.ecgpedia.org ecgpedia]</small>
Image:pulm_embolism_ecg2.jpg|Another example; a patient with pulmonary embolism. Note the tachycardia and right axis.<small>Image courtesy of [http://www.ecgpedia.org ecgpedia]</small>
Image:V18.ht22.jpg|Pulmonary embolism. S1-Q3 and signs of right frontal axis are shown. <small>Image courtesy of Dr Jose Ganseman [http://www.ganseman.com/ecgbibnl.htm#_top000 Dr Ganseman's webpage]</small>
</gallery>
===X-ray===
* In normal range in majority of cases
* [[Chest x ray]]s may reveal an enlarged right descending [[pulmonary artery]]
* Decreased pulmonary vascularity ([[Westermark sign]])
* A wedge shaped infiltrate
* An elevation of the hemidiaphragm ([[Hampton's hump]])
* [[Pleural effusion]] (usually predicts the presence of an infarction)
===Doppler Ultrasonography===
[http://www.peir.net Images courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology] </small>
<gallery>
Image:Deep venous thrombosis 1.jpg|Deep venous thrombosis
Image:Deep venous thrombosis 2.jpg|Deep venous thrombosis
Image:Deep venous thrombosis 3.jpg|Deep venous thrombosis
Image:Deep venous thrombosis 4.jpg|Deep venous thrombosis
</gallery>
(Images shown below are courtesy of RadsWiki)
<gallery>
Image:Greater saphenous vein thrombosis 001.jpg|Greater saphenous vein thrombosis
Image:Greater saphenous vein thrombosis 002.jpg|Greater saphenous vein thrombosis
</gallery>
<gallery>
Image:Upper extremity deep vein thrombosis 001.jpg|Upper extremity deep vein thrombosis
Image:Upper extremity deep vein thrombosis 002.jpg|Upper extremity deep vein thrombosis
Image:Upper extremity deep vein thrombosis 003.jpg|Upper extremity deep vein thrombosis
Image:Upper extremity deep vein thrombosis 004.jpg|Upper extremity deep vein thrombosis
</gallery>
===Echocardiography===
* '''Thrombus in Left Atrial Appendage'''
<googlevideo>1194621255843080155&hl=en</googlevideo>





Revision as of 15:41, 30 August 2012

Thromboembolism

Thromboembolism Microchapters

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Overview

Historical Perspective

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Differentiating Thromboembolism from other Diseases

Epidemiology and Demographics

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Natural History, Complications and Prognosis

Diagnosis

Diagnostic Criteria

History and Symptoms

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Laboratory Findings

Electrocardiogram

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]



Computed Tomography and CT Angiography

Computed tomography with radiocontrast, effectively a pulmonary angiogram imaged by CT and also known as CT pulmonary angiography (CTPA), is increasingly used as the mainstay in diagnosis. Advantages are clinical equivalence, its non-invasive nature, its greater availability to patients, and the possibility of picking up other lung disorders from the differential diagnosis in case there is no pulmonary embolism.

CT findings in Acute PE

  • Thrombus is located centrally within the vascular lumen or occludes the vessel (vessel cut-off sign)
  • Commonly causes distention of the involved vessel.

CT findings in Chronic PE

  • Eccentric and contiguous changes of the vessel wall
  • Reduces the arterial diameter by more than 50%
  • Evidence of recanalization within the thrombus
  • An arterial web is present


Patient with Shortness of Breath


Patient with Acute RBBB

MR and MR Angiography

  • Gadolinium-enhanced MRI is a non-invasive diagnostic modality and has the advantage of no contrast exposure.
  • A potential benefit of MR, is that is incredibly sensitive, perhaps even better than contrast venography, in imaging clot in the inferior vena cava (IVC) and pelvic veins, and these images can be obtained at the same time as the lung scan.
  • It needs to be pointed out, that although the criticism of using CT and MR angio lacks sensitivity when examining the subsegmental arteries, inter-reader agreement was only 66% with pulmonary angiography in PIOPED.

{Images shown below are courtesy of RadsWiki)


Contrast Venography

Contrast venography (also called Venography or phlebography) is the definitive test for diagnosing deep venous thrombosis which taken after a special dye is injected into the vein or even bone marrow.

Contrast venography can also help;

  • to distinguish blood clots from obstructions in the veins
  • to evaluate congenital vein problems
  • to evaluate veins prior to treatment of chronic venous insufficiency
  • to control functioning of deep leg vein valves
  • to identify a vein graft for coronary artery bypass surgery

Pulmonary Angiography

Pulmonary angiography (or pulmonary arteriography) is a cardiological medical procedure. Pulmonary arteries are visualized to detect blood clots (such as a pulmonary embolism) or arteriovenous malformations.

The use of pulmonary angiography has been largely replaced by spiral CT in diagnosis of pulmonary embolism.

Ventilation / Perfusion Scan

Ventilation/perfusion scan (or V/Q scan or lung scintigraphy), which shows that some areas of the lung are being ventilated but not perfused with blood (due to obstruction by a clot). This type of examination is used less often because of the more widespread availability of CT technology, however, it may be useful in patients who have an allergy to iodinated contrast or in pregnancy due to lower radiation exposure than CT. * The ventilation/perfusion ratio (V/Q) Scan: The PIOPED data suggests that normal perfusion scans are almost never associated with recurrent pulmonary embolism, even if anticoagulation is withheld.

Other Methods

Impedance plethysmography

Impedance phlebography or impedance plethysmography is a non-invasive medical test that measures small changes in electrical resistance of the chest, calf or other regions of the body. These measurements reflect blood volume changes, and can indirectly indicate the presence or absence of venous thrombosis. This procedure provides an alternative to venography, which is invasive and requires a great deal of skill to execute adequately and interpret accurately.

For the chest, the technique was developed by NASA to measure the split second impedance changes within the chest, as the heart beats, to calculate both cardiac output and lung water content. This technique has progressed clinically (often now called BioZ, i.e. biologic impedance) and allows low cost, non-invasive estimations of cardiac output and total peripheral resistance, using only 4 skin electrodes, oscillometric blood pressure measurement and lung water volumes with minimal removal of clothing in physician offices having the needed equipment.

For leg veins, the test measures blood volume in the lower leg due to temporary venous obstruction. This is accomplished by inflating a pneumatic cuff around the thigh to sufficient pressure to cut off venous flow but not arterial flow, causing the venous blood pressure to rise until it equals the pressure under the cuff. When the cuff is released there is a rapid venous runoff and a prompt return to the resting blood volume. Venous thrombosis will alter the normal response to temporary venous obstruction in a highly characteristic way, causing a delay in emptying of the venous system after the release of the tourniquet. The increase in blood volume after cuff inflation is also usually diminished.

Treatment

A. Deep Venous Thrombosis

Hospitalization

Treatment at home is an option according to a meta-analysis by the Cochrane Collaboration.[1]

Hospitalization should be considered in patients with more than two of the following risk factors as these patients may have more risk of complications during treatment[2]:

Anticoagulation

Anticoagulation is the usual treatment for DVT. In general, patients are initiated on a brief course (i.e., less than a week) of heparin treatment while they start on a 3- to 6-month course of warfarin (or related vitamin K inhibitors). Low molecular weight heparin (LMWH) is preferred,[3] though unfractionated heparin is given in patients who have a contraindication to LMWH (e.g., renal failure or imminent need for invasive procedure). In patients who have had recurrent DVTs (two or more), anticoagulation is generally "life-long." The Cochrane Collaboration has meta-analyzed the risk and benefits of prolonged anti-coagulation.[4]

An abnormal D-dimer level at the end of treatment might signal the need for continued treatment among patients with a first unprovoked proximal deep-vein thrombosis.[5]

Thrombolysis

Thrombolysis is generally reserved for extensive clot, e.g. an iliofemoral thrombosis. Although a meta-analysis of randomized controlled trials by the Cochrane Collaboration shows improved outcomes with thrombolysis,[6] there may be an increase in serious bleeding complications.

Inferior vena cava filter

Inferior vena cava filter reduces pulmonary embolism[7] and is an option for patients with an absolute contraindiciation to anticoagulant treatment (e.g., cerebral hemorrhage) or those rare patients who have objectively documented recurrent PEs while on anticoagulation, an inferior vena cava filter (also referred to as a Greenfield filter) may prevent pulmonary embolisation of the leg clot. However these filters are themselves potential foci of thrombosis,[8] IVC filters are viewed as a temporizing measure for preventing life-threatening pulmonary embolism.[9]

Compression stockings

Elastic compression stockings should be routinely applied "beginning within 1 month of diagnosis of proximal DVT and continuing for a minimum of 1 year after diagnosis".[3] Starting within one week may be more effective.[10] The stockings in almost all trials were stronger than routine anti-embolism stockings and created either 20-30 mm Hg or 30-40 mm Hg. Most trials used knee-high stockings. A meta-analysis of randomized controlled trials by the Cochrane Collaboration showed reduced incidence of post-phlebitic syndrome.[11] The number needed to treat is quite potent at 4 to 5 patients need to prevent one case of post-phlebitic syndrome.[12]

Surgical Therapy

  • Thrombectomy
  • Venous ligation: Not used anymore

B. Pulmonary Embolism

Emergency treatment at a hospital is necessary to treat pulmonary embolism.

Acute Pharmacotherapy

Chronic Pharmacotherapy

Surgical Therapy

  • Pulmonary embolectomy: it has a high mortality rate.

Treatment in Special Population

1. Pregnancy

2. Elderly

3. Renal Failure

4. Newborn and Early Childhood

American Heart Association's Guidelines

American Family Physician's Guidelines

Complications

  • Postthrombotic syndrome
  • Chronic thromboembolic pulmonary hypertension

Prevention

Pathological Findings

Images courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology

A 67-year-old male was hospitalized because of extensive atherosclerotic cardiovascular disease. Following surgery, during which diseased portions of the femoral arteries were bypassed, he developed massive pulmonary embolism and expired. At autopsy, thrombi were found in the femoral and iliac veins, as well as in the larger pulmonary arteries.

This is a gross photograph of a cut section of lung demonstrating thromboemboli in the pulmonary arteries (arrows).


This is a gross photograph of the heart with the main pulmonary artery opened. Note the thromboembolus filling the pulmonary artery (arrows).


This is a gross photograph of portions of muscle from the legs including sections of leg veins. Note that the leg veins contain thrombus (arrows).


This is a low-power photomicrograph of lung. A large thrombus is lodged at this branch point in the pulmonary artery. Note the hemorrhage and congestion in the surrounding lung parenchyma.


This is a photomicrograph of the wall of the pulmonary artery (1) containing the thromboembolus. In this case the artery wall looks normal. If this was a thrombus instead of a thromboembolus, you would expect to see some damage in the artery wall that would have initiated the thrombus. Note the lines of Zahn in the thromboembolus (arrows).


This is a low-power photomicrograph of the infarcted lung. The tissue is congested and has a very bland appearance due to coagulation necrosis of the lung parenchyma. You can still see the outlines of the alveoli and the cells that make-up the alveoli but there is almost complete loss of nuclei throughout this section.


Thromboembolism: Testes

This is a gross photograph of an infarcted testis. Because of the anatomy of the blood supply to the testis, torsion or the blood vessels often leads to venous occlusion (due to compression of the thin walled veins) but not arterial occlusion. Thus, blood still flows into the testis but it can’t get out! This leads to hypoxia and eventually to hemorrhagic necrosis.


This is a gross photograph of cut section of testis from previous image. The tissue is filled with blood.


Thromboembolism: Bowel infarction

This is a gross photograph of an opened abdomen at autopsy demonstrating loops of infarcted bowel (arrow). Vascular occlusion can lead to ischemic necrosis of the bowel. In this case, a section of bowel herniated through a fibrous connective tissue band and was strangulated, leading to ischemic necrosis.


This is a gross photograph of the fibrous band between the uterus and adjacent tissues. This fibrous scar tissue is probably left over from a previous surgery or an infection. A loop of bowel herniated through the opening produced by this fibrous band and became incarcerated leading to the ischemic necrosis seen in the previous image.


Coronary thrombosis

Images courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology

This is a gross photograph of thrombosed coronary artery (arrows).


This is a low-power photomicrograph of thrombosed coronary artery. The thrombus (1) completely occludes the vessel. Note the layering of the thrombus. The fibrous cap is ruptured (arrow) and there is hemorrhage into the atherosclerotic plaque. Note the cholesterol crystals in the plaque.


This is a higher-power photomicrograph of the ruptured fibrous cap (arrows) with hemorrhage (1) into the atherosclerotic plaque.


This is another high-power photomicrograph of the ruptured fibrous cap (arrows) with hemorrhage (1) into the atherosclerotic plaque. Note the presence of cholesterol crystals.


This is a high-power photomicrograph of thrombus attached to the wall of the vessel. There is early organization of the thrombus (arrow).


This is a higher-power photomicrograph of thrombus attached to the wall of the vessel. Note the early organization with in-growth of fibroblasts and small blood vessels from the wall of the artery (arrows).


In this low-power photomicrograph of another coronary artery from this patient, a mural thrombus has undergone re-organization. The mural thrombus has been invaded by the in-growth of fibroblasts and small blood vessels from the wall of the artery. The thrombotic material has been phagocytosed and removed by macrophages and is replaced by fibrous connective tissue and blood vessels. This re-organized thrombus still compromises the lumen of this vessel.


This is a higher-power photomicrograph of the vessel wall. The adventitia (1) and the media (2) contain inflammatory cells. The recanalized portion of the vessel is composed of fibrous connective tissue and contains numerous small blood vessels. There is a small area of hemorrhage (arrow) in the central portion of this image.


This is a higher-power photomicrograph of another region of the vessel wall. The adventitia (1) and the media (2) contain inflammatory cells. The recanalized portion of the vessel (3) is composed of fibrous connective tissue and contains numerous small blood vessels (arrows).


This is a high-power photomicrograph of the luminal surface of a re-canalized vessel. Note that the vessel lumen is lined by endothelial cells (arrows).


Artificial heart valve thrombosis

Artificial heart valve thrombosis: Gross, aortic valve prosthesis with acute thrombus, ventricular view


Mitral valve prosthesis with thrombosis: Gross, natural color, view from the left atrium, thrombus around rim of caged ball prosthesis.


References

  1. Othieno R, Abu Affan M, Okpo E (2007). "Home versus in-patient treatment for deep vein thrombosis". Cochrane database of systematic reviews (Online) (3): CD003076. doi:10.1002/14651858.CD003076.pub2. PMID 17636714.
  2. Trujillo-Santos J, Herrera S, Page MA; et al. (2006). "Predicting adverse outcome in outpatients with acute deep vein thrombosis. findings from the RIETE Registry". J. Vasc. Surg. 44 (4): 789–93. doi:10.1016/j.jvs.2006.06.032. PMID 16926081.
  3. 3.0 3.1 Snow V, Qaseem A, Barry P; et al. (2007). "Management of venous thromboembolism: a clinical practice guideline from the American College of Physicians and the American Academy of Family Physicians". Ann. Intern. Med. 146 (3): 204–10. PMID 17261857.
  4. Hutten BA, Prins MH (2006). "Duration of treatment with vitamin K antagonists in symptomatic venous thromboembolism". Cochrane database of systematic reviews (Online) (1): CD001367. doi:10.1002/14651858.CD001367.pub2. PMID 16437432.
  5. Palareti G, Cosmi B, Legnani C; et al. (2006). "D-dimer testing to determine the duration of anticoagulation therapy". N. Engl. J. Med. 355 (17): 1780–9. doi:10.1056/NEJMoa054444. PMID 17065639.
  6. Watson L, Armon M. "Thrombolysis for acute deep vein thrombosis". Cochrane Database Syst Rev: CD002783. PMID 15495034.
  7. Decousus H, Leizorovicz A, Parent F, Page Y, Tardy B, Girard P, Laporte S, Faivre R, Charbonnier B, Barral F, Huet Y, Simonneau G (1998). "A clinical trial of vena caval filters in the prevention of pulmonary embolism in patients with proximal deep-vein thrombosis. Prévention du Risque d'Embolie Pulmonaire par Interruption Cave Study Group". N Engl J Med. 338 (7): 409–15. PMID 9459643.
  8. "Eight-year follow-up of patients with permanent vena cava filters in the prevention of pulmonary embolism: the PREPIC (Prevention du Risque d'Embolie Pulmonaire par Interruption Cave) randomized study". Circulation. 112 (3): 416–22. 2005. PMID 16009794.
  9. Young T, Aukes J, Hughes R, Tang H (2007). "Vena caval filters for the prevention of pulmonary embolism". Cochrane database of systematic reviews (Online) (3): CD006212. doi:10.1002/14651858.CD006212.pub2. PMID 17636834.
  10. Prandoni P, Lensing AW, Prins MH; et al. (2004). "Below-knee elastic compression stockings to prevent the post-thrombotic syndrome: a randomized, controlled trial". Ann. Intern. Med. 141 (4): 249–56. PMID 15313740.
  11. Kolbach D, Sandbrink M, Hamulyak K, Neumann H, Prins M. "Non-pharmaceutical measures for prevention of post-thrombotic syndrome". Cochrane Database Syst Rev: CD004174. doi:10.1002/14651858.CD004174.pub2. PMID 14974060.
  12. Kakkos S, Daskalopoulou S, Daskalopoulos M, Nicolaides A, Geroulakos G (2006). "Review on the value of graduated elastic compression stockings after deep vein thrombosis". Thromb Haemost. 96 (4): 441–5. PMID 17003920.

Additional Resources

See Also

External Links

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