Embolism

1. Embolism
An embolus is a detached intravascular solid liquid or gaseous mass that is
transported in the blood to a site distant from its o rigin.

2. Types of emboli
 CLASSIFICATION DEPENDS UPON:
 1.Physical nature of emboli:
 Solid –Thromboemboli,Tumor emboli
 liquid –fat,bone marrow,amniotic fluid.
 Gaseous-air or other gases.
 2.Whether infected or not:
 Bland-sterile
 Septic-infected
 3.Source: The emboli may be exogenous or endogenous
 cardiac emboli
 vascular emboli
• Arterial emboli-e.g;atheromatous plaque,aneurysms.
• Venous embolism-e.g;DPT.Tumor emboli.
• Lymphatic emboli-e.g;tumor emboli.

3. Pulmonary Embolism
 It is defined as an embolism in which emboli occlude the pulmonary arterial
tree.
 Site: Deep leg veins, pelvic veins, venacava.
 Risk factor: Advancing age, post surgery, post operative infection, cancer and
pre existing venous diseases.
 SADDLE EMBOLISM: It is large pulmonary embolus which lodges at the
bifurcation of themain pulmonary artery.No blood flow to both the lungs.
 PARADOXICAL EMBOLISM: Emboli orginates in venous circulation and
bypasses the lungs; Right to left shunt; Block blood flow to the systemic
arteries.
 Consequences:
1. Pulmonary Infarction
2. Pulmonary Hemorrhage
3. Pulmonary Hypertension
4. Minimal effect- Neither infarction nor hemorrhage.

4. Systemic embolism
 It is defined as embolism in which emboli occlude systemic arterial circulation; usually
produces infracts.
 Sources: heart and blood vessels
 Major sites affected by arterial thromboembolism:
1. Lower extremities: Produces gangrene
2. Brain: Produces ischemic necrosis; stroke
3. Intestine: Produce infraction of the bowel .
4. Kidney: Renal artery embolism; peripheral infracts in kidneys
5. Blood vessels: Inflammation of arteries and produces mycotic aneurysm
 Other sites: Spleen and upper extremities; less affected.
 Consequences:
• Arterial emboli tend to pass through the progressively narrow arterial lumen and
lodge at the point where the vessel lumen narrows abruptly .Example : At bifurcation
• The arterial emboli can travel to many sites of the body unlike venous emboli.

5. Fat embolism and Marrow embolism
 It consists of microscopic globules of fat with or without bone marrow
elements ; when released into circulation produces fat embolism
 Causes:
• Trauma to adipose tissue with fracture
• Soft tissue trauma and burns
• During vigorous cardiopulmonary resuscitation
 Manifestation: Mostly asymptomatic.
• Fat embolism syndrome
 Clinical features:
1. Respiratory features- tachypnea, dyspnea, and tachycardia which leads to
respiratory failure .
2. Neurological symptoms- irritability, restlessness, delirium and coma .
 Consequences:
• It depends on size and quantity of fat globules and whether the emboli are
arrested in pulmonary or systemic circulation
• Respiratory distress syndrome , cerebral edema , small hemorrhages and
occasionally microinfracts.

6. PATHOGENESIS
1. By mechanical obstruction
Trauma
Release of emboli consisting of fat
Entry of emboli along with red cells
and platelet aggregates into the
capillaries which are ruptured at the site
of fracture
Due to increased interstitial pressure
above the capillary pressure ;fat
globules enter systemic circulation
Occlusion of pulmonary and cerebral
microvasculature
2. By biochemical injury
Trauma
Release of free fatty acids
Cause platelet activation and granulocyte
recruitment with release of free radicals ,
protease and eicosanoids.
Biochemical injury increases the vascular
damage

7. AIR EMBOLISM
 It occurs when air is introduced into venous or arterial circulation
 Causes:
• Trauma / injury
• Surgery/invasive procedure
• Criminal abortion
 Mechanism : In the circulation, air or gas bubbles tend to coalecse to form frothy mases
which physically obstruct vascular blood flow in the right side of heart
 Consequences: Decompression sickness(acute and chronic)

8. AMNIOTIC EMBOLISM
 Develops when amniotic fluid along with fetal cells and debris
enter the maternal circulation. It enters through open uterine
and cervical veins or tear in the placental membrane.
 Consequences: Fatal disseminated intravascular
coagulation(DIC)
 Morphology
• Amniotic fluid contains within pulmonary vasculature.
• Other findings: Pulmonary edema, Diffused alveolar damage,
and features of DIC.
 Features:
• Abrupt onset –shock, coma and death.
• Bleeding
• Acute respiratory distress syndrome
• Schistosomiasis
• Tumor emboli, Atheromatous emboli, Platelet emboli, Infective
emboli.

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