ATHEROMA: MORPHOLOGY and EFFECTS

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ATHEROMA MORPHOLOGY and EFFECTS

• Brian Angus
• Pathology
• Department
• University of
• Newcastle
• upon Tyne

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CONTENTS
ATHEROMA
INTRODUCTION DEFINITIONS MORPHOLOGY CONSEQUENCES
VASCULAR CONSEQUENCES ORGANS
The fibrous plaque

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INTRODUCTION
Atheroma is the single most important cause of
morbidity and mortality in Western
countries. The most important effects of
atheroma are ischaemic heart disease, peripheral
vascular disease and cerebrovascular
disease. The cause of atheroma is not known, but
many risk factors, and factors which accelerate
disease development have been identified.
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DEFINITIONS
Atheroma Atherosclerosis Athere
porridge. Sclerosis hardening Atheroma is
manifest as the development of deposits of
fibrous tissue and lipid on arterial walls.
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DEFINITIONS
Atheroma is the same as atherosclerosis. However
arteriosclerosis is the medical term for
hardening of the arteries with advancing age. The
media and intima become replaced by fibrous
tissue sometimes with calcification.
Arteriosclerosis is not often of serious
consequence.
No picture
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THE FATTY STREAK
The fatty streak comprises a slightly elevated
zone on the arterial wall caused by accumulation
of a small number of lipid laden histiocytes,
with some free lipid also (not shown). They
occur in all societies, even those without a high
prevelance of atheroma, but are thought to be
the origin of atheroma, as they occur at the same
sites.
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THE FATTY STREAK
.
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THE FIBROUS PLAQUE
This is the second stage in development of
atheroma. Lipid accumulates, free and in foamy
histiocytes. Smooth muscle cells migrate from the
media and proliferate. Fibrosis develops around
the lipid, and forms a cap over the lesion
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THE FIBROUS PLAQUE
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THE COMPLICATED PLAQUE
Ulcers and fissures of the fibrous cap reveal
plaque contents, resulting in thrombosis. The
plaque may undergo calcification, visible on
X-ray. Inflammation associated with the plaque
destroys the media which undergoes fibrosis, and
is weakened.
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PLAQUE MORPHOLOGY
Take a closer look at this picture on the next
slide. Identify the three stages of development
of atherosclerosis.
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PLAQUE MORPHOLOGY
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ARTERIES AFFECTED
All arteries down to 1 mm diameter can be
affected. The brachial arteries are spared. The
renal arteries are spared (except in diabetes).
Maximum atheroma occurs at sites of
haemodynamic stress e.g. bifurcations.
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VASCULAR CONSEQUENCES
Atheroma has the following effects on vessels and
the organs/parts served LUMENAL NARROWING
ISCHAEMIA LUMENAL OCCLUSION
INFARCTION EMBOLISM ISCHAEMIA AND
INFARCTION WEAKENED WALL ANEURYSM
Coronary artery thrombosis
The following slides show each of these in turn.
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VASCULAR CONSEQUENCESLUMENAL NARROWING
Lumenal narrowing results in ischaemia if severe
enough. Usually a much greater degree of
narrowing is required to cause symptoms than in
the diagram. An example is chest pain on
exertion due to narrowing of the coronary
arteries (angina).
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VASCULAR CONSEQUENCESLUMENAL OCCLUSION
Lumenal occlusion is due to thrombosis. This
will often result in infarction of the part
served. An example is myocardial infarction due
to thrombosis of a coronary artery.

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VASCULAR EFFECTSEMBOLISM
This usually occurs when non occlusive thrombus
breaks off and travels with the blood flow until
it occludes a distal vessel. A clinical example
is transient cerebral ischaemic attacks due to
embolism from carotid atheroma. Embolism of lipid
rich plaque contents is rare.
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VASCULAR EFFECTSANEURYSM
The commonest site for aneurysm is the abdominal
aorta, as shown here. The aorta dilates, becomes
filled with lamellated thrombus, and eventually
ruptures.
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VASCULAR EFFECTSANEURYSM
The patient with a ruptured aneurysm presents
with severe abdominal or back pain, and is often
shocked due to blood loss. This is a surgical
emergency, and grafting is required.
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VASCULAR EFFECTSANEURYSM
The patient with a ruptured aneurysm presents
with severe abdominal or back pain, and is often
shocked due to blood loss. This is a surgical
emergency, and grafting is required.
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ORGAN CONSEQUENCES
We will now examine the consequences of
narrowing, occlusion and embolism on the
principal organs affected, namely the

HEART BRAIN LEGS GUT and KIDNEYS
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ORGAN CONSEQUENCES 1 HEART ANGINA
Narrowing of the coronary arteries results in
chest pain on exertion - angina.

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ORGANCONSEQUENCES 1 HEART ANGINA

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ORGAN CONSEQUENCESHEART INFARCTION
Thrombotic occlusion of a coronary artery
results in myocardial infarction. The photograph
shows a 10 day old infarct.

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HEART INFARCTION


ddddddddddddddddddddddddddddddddddddddd
Myocardial infarct
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ORGAN CONSEQUENCESBRAIN INFARCTION
Thrombotic occlusion of a cerebral artery results
in cerebral infarction. The patient will usually
present with neurological deficit and reduced
conscious level the precise features depend on
the site and size of the infarct.

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BRAIN INFARCTION


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ORGAN CONSEQUENCESBRAIN TRANSIENT ISCHAEMIC
ATTACKS
Thrombosis over the carotid arteries may result
in release of small emboli. These travel to the
brain. The patient suffers transient neurological
deficit, or loss of consciousness. These small
emboli usually lyse without permanent deficit,
but there is always the risk of this.

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ORGAN CONSEQUENCESLEG CLAUDICATION
Atheroma of the femoral artery results in reduced
blood supply to the lower leg. The patient
experiences pain in the calf on walking-
claudication. This is relieved by rest and the
patients progress is punctuated by alternate
walking and resting intermittent claudication.

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ORGAN CONSEQUENCESLEG GANGRENE
Thrombosis may develop over an atheromatous
plaque in the femoral (or other supplying) artery
resulting in infarction of all tissues served
(gangrene). This can also occur in severe
stenotic atheroma if something else reduces blood
flow, e.g. development of cardiac failure.

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LEG GANGRENE

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ORGAN CONSEQUENCESGUT INFARCTION
Thrombosis may develop over an atheromatous
plaque in one of the mesenteric arteries
resulting in infarction. The photograph shows
small bowel infarction.

University of Utah
Small bowel infarction
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GUT INFARCTION

University of Utah
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ORGAN CONSEQUENCESCOLON ISCHAEMIC COLITIS
Lack of blood to the colon results in ischaemic
damage short of infarction. The patient has pain
and bloody diarrhoea.

Narrowed inferior mesenteric artery to colon
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ORGAN CONSEQUENCESKIDNEY HYPERTENSION
The renal arteries are usually spared severe
atheroma but sometimes, especially in diabetic
patients, the origin of the renal artery is
affected. The kidney gradually becomes atrophic
due to chronic ischaemia. The underperfused
kidney releases renin resulting in renal
hypertention, with consequent risk of heart
failure and stroke.

Narrowed origin of left renal artery.
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KIDNEY Atheroma at origin of renal artery


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END OF PRESENTATION

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