atheroma: morphology and effects 1 atheroma: morphology and effects brian angus pathology department...

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ATHEROMA: MORPHOLOGY AND EFFECTS

ATHEROMA: MORPHOLOGY and EFFECTS

Brian Angus

PathologyDepartment

University of Newcastleupon Tyne

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CONTENTS

INTRODUCTION

DEFINITIONS

MORPHOLOGY

CONSEQUENCES: VASCULAR

CONSEQUENCES: ORGANSThe fibrous plaque

ATHEROMA

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INTRODUCTIONAtheroma 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 stresse.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

The following slides show each of these in turn.

Coronary artery thrombosis

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VASCULAR CONSEQUENCES:LUMENAL 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 EFFECTS:EMBOLISM

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 EFFECTS:ANEURYSM

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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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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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

Myocardial infarctddddddddddddddddddddddddddddddddddddddd

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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 patient’s 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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atheroma: morphology and effects 1 atheroma: morphology and effects brian angus pathology department...

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