Embolism

This article is about the vascular phenomenon. For other uses, see Embolism (disambiguation).

Not to be confused with ebullism or aneurysm.

Embolism
Classification and external resources
Specialty	Vascular surgery
ICD-10	I74, I82, O88, T79.0-T79.1
ICD-9-CM	444.9
DiseasesDB	18165
MeSH	D004617

An embolism is the lodging of an embolus, which may be a blood clot, fat globule, gas bubble or foreign material in the bloodstream.^[1] This can cause a blockage in a blood vessel.^[2] Such a blockage (vascular occlusion) may affect a part of the body distanced from the actual site of the embolism. This is in contrast to a thrombus, which causes a blockage at the site of origin.^[3]

Etymology

The word embolism comes from the Greek ἐμβολισμός, meaning "interposition".

Classification

There are different types of embolism, some of which are listed below.

Arterial or venous

Embolism can be classified as to where it enters the circulation either in arteries or in veins. Arterial embolism are those that follow and, if not dissolved on the way, lodge in a more distal part of the systemic circulation. Sometimes, multiple classifications apply; for instance a pulmonary embolism is classified as an arterial embolism as well,^[4] in the sense that the clot follows the pulmonary artery carrying deoxygenated blood away from the heart. However, pulmonary embolism is generally classified as a form of venous embolism, because the embolus forms in veins, e.g. deep vein thrombosis.

Arterial

Main article: Arterial embolism

Arterial embolism can cause occlusion in any part of the body. It is a major cause of infarction, tissue death due to the blockage of blood supply.

An embolus lodging in the brain from either the heart or a carotid artery will most likely be the cause of a stroke due to ischemia.

An arterial embolus might originate in the heart (from a thrombus in the left atrium, following atrial fibrillation or be a septic embolus resulting from endocarditis). Emboli of cardiac origin are frequently encountered in clinical practice. Thrombus formation within the atrium occurs mainly in patients with mitral valve disease, and especially in those with mitral valve stenosis (narrowing), with atrial fibrillation (AF). In the absence of AF, pure mitral regurgitation has a low incidence of thromboembolism.

The risk of emboli forming in idiopathic AF depends on other risk factors such as increasing age, hypertension, diabetes, recent heart failure, or previous stroke. Thrombus formation can also take place within the ventricles, and it occurs in approximately 30% of anterior-wall myocardial infarctions, compared with only 5% of inferior ones. Some other risk factors are poor ejection fraction (<35%), size of infarct, and the presence of AF. In the first three months after infarction, left-ventricle aneurysms have a 10% risk of emboli forming.

Patients with prosthetic valves also carry a significant increase in risk of thromboembolism. Risk varies, based on the valve type (bioprosthetic or mechanical); the position (mitral or aortic); and the presence of other factors such as AF, left-ventricular dysfunction, and previous emboli.

Emboli often have more-serious consequences when they occur in the so-called "end circulation": areas of the body that have no redundant blood supply, such as the brain and heart.

Venous

Further information: Pulmonary embolism

Assuming a normal circulation, an embolus formed in a systemic vein will always impact in the lungs, after passing through the right side of the heart. This will form a pulmonary embolism that will result in a blockage of the main artery of the lung and can be a complication of deep-vein thrombosis. The most common sites of origin of pulmonary emboli are the femoral veins. The deep veins of the calf are the most common sites of actual thrombi.

Paradoxical (venous to arterial)

In paradoxical embolism, also known as crossed embolism, an embolus from the veins crosses to the arterial blood system. This is generally found only with heart problems such as septal defects (holes in the cardiac septum) between the atria or ventricles. The most common such abnormality is patent foramen ovale, occurring in about 25% of the adult population, but here the defect functions as a valve which is normally closed, because pressure is slightly higher in the left side of the heart. Sometimes, for example if a patient coughs just when an embolus is passing, it might cross to the arterial system.

Direction

The direction of the embolus can be one of two types:

Anterograde
Retrograde

In anterograde embolism, the movement of emboli is in the direction of blood flow. In retrograde embolism, however, the emboli move in opposition to the blood flow direction; this is usually significant only in blood vessels with low pressure (veins) or with emboli of high weight.

References

↑ Dorland's (2012). Dowland's Illustrated Medical Dictionary (32nd ed.). Elsevier. p. 606. ISBN 978-1-4160-6257-8.
↑ Britannica concise encyclopedia 2007
↑ http://news.healingwell.com/index.php?p=news1&id=536001
↑ MedlinePlus > Arterial embolism Sean O. Stitham, MD and David C. Dugdale III, MD. Also reviewed by David Zieve, MD. Reviewed last on: 5/8/2008. Alternative link:

External links

MR of Fat Embolism Brain Injury from Fat Embolism

Arteries, arterioles
and capillaries

Inflammation

Arterial occlusive disease /
peripheral artery disease

Arteriosclerosis	Atherosclerosis Foam cell Fatty streak Atheroma Intermittent claudication Critical limb ischemia Monckeberg's arteriosclerosis Arteriolosclerosis Hyaline Hyperplastic Cholesterol LDL Oxycholesterol Trans fat

Stenosis	Carotid artery stenosis Renal artery stenosis

Other	Aortoiliac occlusive disease Degos disease Erythromelalgia Fibromuscular dysplasia Raynaud's phenomenon

Aneurysm / dissection /
pseudoaneurysm

Vascular malformation

Vascular nevus

Veins

Inflammation	Phlebitis

Venous thrombosis / Thrombophlebitis	primarily lower limb Deep vein thrombosis abdomen Hepatic veno-occlusive disease Budd–Chiari syndrome May–Thurner syndrome Portal vein thrombosis Renal vein thrombosis upper limb / torso Mondor's disease Paget–Schroetter disease head Cerebral venous sinus thrombosis Post-thrombotic syndrome

Varicose veins	Gastric varices Portacaval anastomosis Caput medusae Esophageal varices Hemorrhoid Varicocele

Other	Chronic venous insufficiency Chronic cerebrospinal venous insufficiency Superior vena cava syndrome Inferior vena cava syndrome Venous ulcer

Arteries or veins

Blood pressure

Hypertension	Hypertensive heart disease Hypertensive emergency Hypertensive nephropathy Essential hypertension Secondary hypertension Renovascular hypertension Benign hypertension Pulmonary hypertension Systolic hypertension White coat hypertension

Hypotension	Orthostatic hypotension

Pathology of pregnancy, childbirth and the puerperium (O, 630–679)

Pregnancy

Pregnancy with
abortive outcome

Oedema, proteinuria and
hypertensive disorders

Other, predominantly
related to pregnancy

Digestive system	Acute fatty liver of pregnancy Gestational diabetes Hepatitis E Hyperemesis gravidarum Intrahepatic cholestasis of pregnancy

Integumentary system / dermatoses of pregnancy	Gestational pemphigoid Impetigo herpetiformis Intrahepatic cholestasis of pregnancy Linea nigra Prurigo gestationis Pruritic folliculitis of pregnancy Pruritic urticarial papules and plaques of pregnancy (PUPPP) Striae gravidarum

Nervous system	Chorea gravidarum

Blood	Gestational thrombocytopenia Pregnancy-induced hypercoagulability

Maternal care related to the
fetus and amniotic cavity

Labor

Puerperal

Other

Certain early complications of trauma (T79, 958)

Certain early complications of trauma	Embolism air fat Crush syndrome / Rhabdomyolysis Contracture / Volkmann's contracture / Compartment syndrome Subcutaneous emphysema

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