Infarction
How a blocked vessel kills a territory of tissue: why some infarcts are pale and others red, why they are wedge-shaped, how an infarct changes from hours to months, and how infarcts differ in the heart, brain, lung, kidney, spleen and bowel.
By the end, you can
- Define an infarct and explain the factors that decide whether occluding a vessel causes one.
- Distinguish pale (white) from red (haemorrhagic) infarcts and relate each to the blood supply of the organ.
- Describe how an infarct evolves from coagulative necrosis to scar, and why brain infarcts liquefy.
- Relate infarcts in the heart, brain, lung, kidney, spleen and bowel to their effects.
- Explain how septic infarcts and venous infarction differ from the usual arterial infarct.
- Date an infarct from its appearance, recognise the tests and classifications examiners ask about, and explain how reperfusion within the time window, antithrombotic drugs and protecting the surviving tissue limit an infarct.
What it is
An infarct is an area of tissue necrosis caused by ischaemia, almost always from sudden occlusion of the artery that supplies it and less often of the vein that drains it. Most infarcts are coagulative necrosis, but the brain liquefies. Infarcts are pale (white) in solid organs supplied by end arteries, and red (haemorrhagic) where blood still enters the dead tissue.
3 types to tell apart
- Pale (white, anaemic) infarct
- Arterial occlusion in a solid organ with end arteries, such as the heart, kidney or spleen; little blood enters the dead tissue.
- Red (haemorrhagic) infarct
- Venous occlusion, loose tissue, a dual or collateral supply (lung, bowel), a congested organ, or flow restored to dead tissue: blood fills the infarct.
- Septic infarct
- An infected embolus, such as a fragment of a vegetation on an infected heart valve, turns the infarct into an abscess.
US spelling: ischaemia → ischemia, haemorrhagic → hemorrhagic.
Normal function
Each artery supplies its own territory
Arteries branch like a tree. In the kidney, each divides at the hilum into branches that fan out towards the surface and do not join one another: they are end arteries. Each branch supplies a cone-shaped territory, its apex at the hilum and its base at the capsule. The spleen and the retina are supplied the same way.
The heart and brain have small connections between neighbouring arteries, too small to take over quickly when one artery blocks suddenly (functional end arteries). The lung has two supplies (pulmonary and bronchial arteries), the liver two (hepatic artery and portal vein), and the bowel is supplied by arcades of linked arteries.
Underlying change · Step 1 of 4
When a blocked vessel causes an infarct
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 2 of 4
Pale and red infarcts, and their shape
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 4
From dead tissue to scar
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 4 of 4
Infarcts organ by organ
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 4 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .