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INFARCTIONINFARCTION
Dr.CSBR.Prasad, M.D.
Common clinical examples ofCommon clinical examples of
infarction:infarction:
• Myocardial infarction
• Cerebral infarctio...
Atrial fibrillationAtrial fibrillation
with mural thrombiwith mural thrombi
INFARCTIONINFARCTION
Def: An infarct is an area of
ischemic necrosis caused by
occlusion of either the arterial supply
or ...
Basis of infarction:Basis of infarction:
Vascular compromise
• Obstruction to arterial supply
• Impeded venous drainage
Common causes:Common causes:
Arterial occlusion:Arterial occlusion:
• 99% result from arterial occlusion (thrombotic or em...
ClassificationClassification
Based on the colour & presence or absence of
infection
MorphologyMorphology
Red (hemorrhagic) infarctsRed (hemorrhagic) infarcts occur
(1) with venous occlusions (such as in ova...
MorphologyMorphology
White (anemic) infarctsWhite (anemic) infarcts occur
with arterial occlusions in solid organs with
en...
Most of the infarcts are wedgeMost of the infarcts are wedge
shapedshaped
• with the occluded vessel at the apex and
the p...
Margins become hyperemicMargins become hyperemic
• Initially:Initially: all infarcts are poorly defined and
slightly hemor...
Examples of infarcts:
A, Hemorrhagic, roughly wedge-shaped pulmonary infarct.
B, Sharply demarcated white infarct in the s...
Pulmonary infarctionPulmonary infarction
Splenic infarctionSplenic infarction
Histology of infarctionHistology of infarction
Changes depends on time
Ischemic coagulative necrosis
Inflammation
Liquifac...
Remote kidney infarct,
now replaced by a large
fibrotic cortical scar.
Factors That InfluenceFactors That Influence
Development of an InfarctDevelopment of an Infarct
The major determinants inc...
Factors That InfluenceFactors That Influence
Development of an InfarctDevelopment of an Infarct
The major determinants:
(1...
Factors That InfluenceFactors That Influence
Development of an InfarctDevelopment of an Infarct
The major determinants:
(2...
Factors That InfluenceFactors That Influence
Development of an InfarctDevelopment of an Infarct
The major determinants:
(3...
Factors That InfluenceFactors That Influence
Development of an InfarctDevelopment of an Infarct
The major determinants:
(4...
Factors That InfluenceFactors That Influence
Development of an InfarctDevelopment of an Infarct
The major determinants:
(4...
Compartment syndrome
Compartment syndrome
Inguinal hernia
Inguinal hernia
Strangulated hernia
Umbilical hernia
Umbilical Hernia
Umbilical hernia
Volvulus
Volvulus
Volvulus involving
caecum
Torsion - ovary
Torsion - ovary
Torsion - ovary
Torsion – Fallopian tube
Torsion testis – torsion of hydatid
Torsion - testis
Gangrene ofGangrene of
the fingersthe fingers
E N DE N D
6 infarction
6 infarction
6 infarction
6 infarction
6 infarction
6 infarction
6 infarction
6 infarction
6 infarction
6 infarction
6 infarction
6 infarction
6 infarction
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6 infarction

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6 infarction

  1. 1. INFARCTIONINFARCTION Dr.CSBR.Prasad, M.D.
  2. 2. Common clinical examples ofCommon clinical examples of infarction:infarction: • Myocardial infarction • Cerebral infarction • Pulmonary infarction • Gangrene of limbs
  3. 3. Atrial fibrillationAtrial fibrillation with mural thrombiwith mural thrombi
  4. 4. INFARCTIONINFARCTION Def: An infarct is an area of ischemic necrosis caused by occlusion of either the arterial supply or the venous drainage in a particular tissue
  5. 5. Basis of infarction:Basis of infarction: Vascular compromise • Obstruction to arterial supply • Impeded venous drainage
  6. 6. Common causes:Common causes: Arterial occlusion:Arterial occlusion: • 99% result from arterial occlusion (thrombotic or embolic events) • Other causes: local vasospasm expansion of an atheroma (hemorrhage within a plaque) extrinsic compression of a vessel (e.g., by tumor) twisting of the vessels (e.g., in testicular torsion or bowel volvulus) compression of the blood supply by edema or by entrapment in a hernia sac traumatic rupture of the blood supply Venous occlusion:Venous occlusion: (organs with single veinous out flow) • Thrombosis
  7. 7. ClassificationClassification Based on the colour & presence or absence of infection
  8. 8. MorphologyMorphology Red (hemorrhagic) infarctsRed (hemorrhagic) infarcts occur (1) with venous occlusions (such as in ovarian torsion); (2) in loose tissues (such as lung), which allow blood to collect in the infarcted zone; (3) in tissues with dual circulations (e.g., lung and small intestine), permitting flow of blood from the unobstructed vessel into the necrotic zone (obviously such perfusion is not sufficient to rescue the ischemic tissues); (4) in tissues that were previously congested because of sluggish venous outflow; and (5) when flow is re-established to a site of previous arterial occlusion and necrosis (e.g., following fragmentation of an occlusive embolus or angioplasty of a thrombotic lesion)
  9. 9. MorphologyMorphology White (anemic) infarctsWhite (anemic) infarcts occur with arterial occlusions in solid organs with end-arterial circulation (such as heart, spleen, and kidney), where the solidity of the tissue limits the amount of hemorrhage that can seep into the area of ischemic necrosis from adjoining capillary beds
  10. 10. Most of the infarcts are wedgeMost of the infarcts are wedge shapedshaped • with the occluded vessel at the apex and the periphery of the organ forming the base • when the base is a serosal surface, there is often an overlying fibrinous exudate. • The lateral margins may be irregular, reflecting the pattern of vascular supply from adjacent vessels.
  11. 11. Margins become hyperemicMargins become hyperemic • Initially:Initially: all infarcts are poorly defined and slightly hemorrhagic • Later:Later: margins tend to become better defined by a narrow rim of hyperemia attributable to inflammation at the edge of the lesion.
  12. 12. Examples of infarcts: A, Hemorrhagic, roughly wedge-shaped pulmonary infarct. B, Sharply demarcated white infarct in the spleen.
  13. 13. Pulmonary infarctionPulmonary infarction
  14. 14. Splenic infarctionSplenic infarction
  15. 15. Histology of infarctionHistology of infarction Changes depends on time Ischemic coagulative necrosis Inflammation Liquifactive necrosis Abscess formation Scar tissue
  16. 16. Remote kidney infarct, now replaced by a large fibrotic cortical scar.
  17. 17. Factors That InfluenceFactors That Influence Development of an InfarctDevelopment of an Infarct The major determinants include: (1) the nature of the vascular supply; (2) the rate of development of the occlusion; (3) the vulnerability of a given tissue to hypoxia; and (4) the blood oxygen content.
  18. 18. Factors That InfluenceFactors That Influence Development of an InfarctDevelopment of an Infarct The major determinants: (1) Nature of the vascular supply (double or single blood supply) The availability of an alternative blood supply is the most important factor in determining whether occlusion of a vessel will cause damage. Lungs, for example, have a dual pulmonary and bronchial artery blood supply; thus, obstruction of a small pulmonary arteriole does not cause infarction in an otherwise healthy individual with an intact bronchial circulation. Similarly, the liver, with its dual hepatic artery and portal vein circulation, and the hand and forearm, with their dual radial and ulnar arterial supply, are all relatively insensitive to infarction. In contrast, renal and splenic circulations are end-arterial, and obstruction of such vessels generally causes infarction.
  19. 19. Factors That InfluenceFactors That Influence Development of an InfarctDevelopment of an Infarct The major determinants: (2) Rate of development of occlusion. Slowly developing occlusions are less likely to cause infarction because they provide time for the development of alternative perfusion pathways. For example, small interarteriolar anastomoses —normally with minimal functional flow—interconnect the three major coronary arteries in the heart. If one of the coronaries is only slowly occluded (i.e., by an encroaching atherosclerotic plaque), flow within this collateral circulation may increase sufficiently to prevent infarction, even though the major coronary artery is eventually occluded.
  20. 20. Factors That InfluenceFactors That Influence Development of an InfarctDevelopment of an Infarct The major determinants: (3) Vulnerability to hypoxia. The susceptibility of a tissue to hypoxia influences the likelihood of infarction. Neurons undergo irreversible damage when deprived of their blood supply for only 3 to 4 minutes. Myocardial cells, although hardier than neurons, are also quite sensitive and die after only 20 to 30 minutes of ischemia. In contrast, fibroblasts within myocardium remain viable even after many hours of ischemia
  21. 21. Factors That InfluenceFactors That Influence Development of an InfarctDevelopment of an Infarct The major determinants: (4) Oxygen content of blood. The partial pressure of oxygen in blood also determines the outcome of vascular occlusion. Partial flow obstruction of a small vessel in an anemic or cyanotic patient might lead to tissue infarction, whereas it would be without effect under conditions of normal oxygen tension. In this way, congestive heart failure, with compromised flow and ventilation, could cause infarction in the setting of an otherwise inconsequential blockage.
  22. 22. Factors That InfluenceFactors That Influence Development of an InfarctDevelopment of an Infarct The major determinants: (4) Oxygen content of blood. What is the critical value for HGB ?
  23. 23. Compartment syndrome
  24. 24. Compartment syndrome
  25. 25. Inguinal hernia
  26. 26. Inguinal hernia
  27. 27. Strangulated hernia
  28. 28. Umbilical hernia
  29. 29. Umbilical Hernia
  30. 30. Umbilical hernia
  31. 31. Volvulus
  32. 32. Volvulus
  33. 33. Volvulus involving caecum
  34. 34. Torsion - ovary
  35. 35. Torsion - ovary
  36. 36. Torsion - ovary
  37. 37. Torsion – Fallopian tube
  38. 38. Torsion testis – torsion of hydatid
  39. 39. Torsion - testis
  40. 40. Gangrene ofGangrene of the fingersthe fingers
  41. 41. E N DE N D

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