This document discusses embolism, infarction, and their causes and classifications. It defines an embolism as a detached mass carried by the blood to distant sites, which can lodge and block vessels, causing tissue dysfunction. Emboli sources include thrombi, fat, air, debris. Embolisms are classified as pulmonary (95% from DVTs), systemic (sites include legs, brain, intestines, kidneys). Infarctions are areas of ischemic necrosis due to blood flow obstruction. They are classified as hemorrhagic, white, septic based on appearance and presence of infection. Infarcts are eventually replaced by scar tissue.

1. Dr. Abdul Rehman
Embolism & Infarction

2. Learning Outcomes!
• Explain the causes of embolus
• Classify different forms of embolus
• Concept of infarction, classification and its morphology

3. • An embolus is a detached intravascular solid, liquid, or gaseous mass
that is carried by the blood to a site distant from its point oforigin
(dislodged thrombi)
• Emboli lodge in vessels too small to permit further passage, resulting in
partial or complete vascular occlusion
• Leads to tissue dysfunction and infarction
• Source of emboli: Dislodged thrombus (mainly), fat droplets, bubbles of
air or nitrogen, atherosclerotic debris (cholesterol emboli), tumor
fragments, bits of bone marrow, or amniotic fluid
EMBOLISM
Pulmonary Thromboembolism
95% of venous emboli originate from deep leg vein thrombi (DVT)
• Emboli traveling within the arterialcirculation
• Most (80%) arise from intra-cardiac muralthrombi
• Two thirds of which are associated with leftventricular infarcts
Systemic Thromboembolism

4. Large embolus derived from a lower
extremity deep venous thrombosis
and now impacted in a pulmonary
artery branch (Saddle Embolus)
Major sites for arteriolar embolization:
1. Lower extremities(75%)
2. Brain (10%)
3. Others: Intestines, kidneys, spleen
Systemic Thromboembolism

5. 1- Fat Embolism
• Microscopic fat globules may be found in the circulation after fractures of
long bones (which have fatty marrow) or,rarely, in the setting of soft tissue
trauma and burns
• Symptoms include pulmonary insufficiency, thrombocytopenia, anemia
and neurological damage
Bone marrow embolus in pulmonary vessel.
The cleared vacuoles represent marrow fat
that is now impacted in a distal vessel along
with the cellular hematopoietic precursors
FatEmbolusinaglomerulus
Types of Embolus

6. 2- AirEmbolism
• Gas bubbles within the circulation can obstruct vascular flow and can
cause distal ischemic injury
• Enter the circulation during cardiac surgery, neurosurgery, obstetric
procedures or as a consequence of chest wall injury
• Decompression sickness in scuba drivers & underwater construction
workers
• In excess of 100 cc is required to have a clinical effect
• Underlying cause is the infusion of amniotic fluid or fetal tissue into the
maternal circulation via tears in the placental membranes or rupture of
uterine veins
• Characterized by sudden severe dyspnea, cyanosis, and hypotensive shock,
followed by seizures and coma
3- Amniotic FluidEmbolism

7. • Definition: An infarct is an area of ischemic necrosis
• Underlying Cause: Occlusion of vascular supply to the affected tissue
• Infarction is necrosis resulting from ischemia caused by obstruction of the
blood supply to the affected area
• Pathogenesis:
Obstruction Hypoxia Reversible injury Irreversible injury
(necrosis)
Causes :
Intraluminal Intramural Extramural
- Thrombosis - Vasospasm -Tumor
- Embolism - Sclerosis - Ligation
- Atheroma - Vasculitis - Torsion
INFARCTION

8. INFARCTION

9. • Dominant histologic finding : ischemic coagulative necrosis
ischemic liquefactive necrosis (Brain)
• An inflammatory response begins to develop along the margins of
infarcts within a few hours and usually is well defined within 1 to 2 days
• Most infarcts are ultimately replaced by scar tissue
• Based on their color (reflecting the amount of hemorrhage)
1. Red (hemorrhagic) infarct 2. White (anemic) infarct
• Based on the presence or absenceof microbial infection
1. Septic infarct 2. Bland infarct
• Infarcts tend to be wedge shaped with the occluded vessel
at the apex and the organ periphery forming the base
Classification of Infarct

10. • Red (hemorrhagic) infarcts occur
(1) with venous occlusions (such as in ovariantorsion)
(2) With arterial occlusion in tissues with dual circulations
(lung & small intestine)
• White (anemic) infarcts occur
With arterial occlusions in solid organs with end- arterial
circulation (heart, spleen, and kidney)
• Septic infarctions may develop when embolization occurs by
fragmentation of a bacterial vegetation from a heart valve or when
microbes seed an area of necrotic tissue
➢ Factors that influence infarct development:
• Collateral blood supplies
• Rate at which an obstruction develops
• Intrinsic tissue susceptibility to ischemic injury and blood oxygenation

11. Types of infarct:
(A) Hemorrhagic, roughly wedge-shaped pulmonary infarct
(B) Sharply demarcated white infarct in the spleen

12. Remote kidney infarct replaced by a large fibrotic corticalscar