Aneurysms of blood vessels - PowerPoint Presentation

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Aneurysms of blood vessels

By Dr. S.Homathy

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Aneurysm

It is a localized dilatation of blood vessel or the heart due to a weakening of its wall.

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Classification

Aneurysms may be classified

by

type

,

location, the affected vessel. Other factors may also influence the pathology and diagnosis of aneurysms.

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True and false aneurysms

A true aneurysm

is one that involves all three layers of the wall of an artery (intima, media and adventitia

).

True aneurysms

include atherosclerotic, syphilitic,

and congenital aneurysms

,

ventricular aneurysms that follow transmural myocardial infarctions aneurysms that involve all layers of the attenuated wall of the heart are also considered true aneurysms

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A false aneurysm or pseudo-aneurysm

does not primarily involve such distortion of the vessel. It is a collection of blood leaking completely out of an artery or vein ( extravascular

haematoma

)

but confined next to the vessel by the surrounding tissue.

It freely communicates with the intravascular space (

pulsating haematoma)This blood-filled cavity will eventually either thrombose (clot) enough to seal the leak or rupture out of the tougher tissue enclosing it and flow freely between layers of other tissues or into looser tissues.

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Pseudoaneurysms can be caused by trauma that punctures the artery and are a known complication of percutaneous arterial procedures, such as

arteriography

arterial grafting,

or use of an artery for injection,

such as by drug abusers unable to find a usable vein

Ventricular aneurysm after MI that are contained by a pericardial adhesionLike true aneurysms, they may be felt as an abnormal pulsatile mass on palpation.

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Morphology

Aneurysms are classified by their macroscopic shape and size and are

described as either

saccular

fusiform

. Saccular aneurysms are

spherical in shape

and involve only a portion of the vessel wall; they vary in size from 5 to 20 cm (8 in) in diameter, and are often filled, either partially or fully, by thrombus.

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Fusiform

("spindle-shaped") aneurysms areInvolve diffuse, circumferential dilation of a long vascular segment

variable in both their diameter and length;

their diameters can extend up to 20 cm (8 in).

They often involve

large portions of the ascending and transverse aortic arch, the abdominal aorta, or

less frequently the iliac arteries.

The shape of an aneurysm is not pathognomonic for a specific diseaseCan involveextensive portion of the aortic arch

Abdominal aorta

iliacs

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Location

Cerebral aneurysms, also known as intracranial or brain aneurysms,

occur

most commonly in the anterior cerebral artery, which is part of the circle of Willis.

The

next most common sites of cerebral aneurysm occurrence are in the internal carotid

artery

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Many

non-intracranial aneurysms arise distal to the origin of the renal arteries at the

infrarenal

 abdominal aorta,

a condition some have postulated to be related to 

atherosclerosis.

However, increasing evidence suggests abdominal aortic aneurysms are a wholly separate pathology.

TraumaCongenital defectsInfections (mycotic aneurysm)- syphilisvasculitis

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The thoracic aorta can also be involved.

One common form of thoracic aortic aneurysm involves widening of the proximal aorta and the aortic root, which leads to aortic insufficiency.Aneurysms can also occur in the legs, particularly in the deep vessels (e.g., the popliteal vessels in the knee).

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Arterial and venous

Arterial aneurysms are much more common,

but

 venous aneurysms do happen

example

, the

popliteal venous

aneurysm13Slide14

Abdominal Aortic Aneurysms (AAA

)Definition

Diameter of the aorta 1.5 times

greater than normal.

Most are

infrarenal

, and a significant number extend down into one or both iliac arteries

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Pathogenesis

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Primary Risk Factors

Men over 60

Men are four times more likely to develop AAAs, but 20%

do occur in women.

Smokers

Current smokers are seven times more likely to develop AAA than non-smokers.

Former smokers are three times more likely.

Family History20% of AAA patients have a relative with the condition

Gene

Marfan, Ehlers-Danlos syndrome

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Secondary risk factors

Obesity High blood pressure High cholesterol

Atherosclerosis

Cardiovascular disease

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Important causes of aortic aneurysm

AS

Intima

infiltrated by atherosclerosis and thinned media.

Possible

intraluminal

thrombus and adventitia infiltrated by inflammatory cells

Cystic medial degeneration of the arterial mediaOther causes includeTraumaCongenital defects

Infections

Syphilis

vasculitis18Slide19

Infection of the major artery weaken its wall

Mycotic aneurysmCan originate From

embolizationof

a septic thrombus ( IE)

Extension of an adjacent

suppurative

process

Circulating organisms directly infecting the arterial wall.19Slide20

Morphology

Usually(about 90%) positioned below the renal artery and above the bifurcation of the aorta.AAA saccular

or

fusiform

As large as 15cm in dm and as long as 25 cm

Aneurysm and nearby aorta often contain

atheromatous

ulcers covered by granular mural thrombi.Prime site for atheroemboli that lodge in the vessels of the kidneys or lower extremities

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A thrombus frequently fills the part of the distal segment.

Two variant of AAAInflammatory AAA consist of dense

periaortic

fibrosis containing an abundant

lymphoplasmacytic

inflammatory reaction

With many MP and often giant cells

Mycotic AAAsAtheromatous lesions become infected by circulating organism in the wallDestroy the media – rapid dilation and rupture

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Clinical features

Rupture into the peritoneal cavity- fatal haemorrhage

Obstruction of a branch vessel – down stream tissue

ischaemic

injury

Iliac- leg

Renal –kidney

Mesenteric- GITVertibral branches- spinal cordEmbolism from atheroma or thrombiImpingment

on an adjacent structure

Abdominal mass

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Risk of rupture directly related to the size of the aneurysm

If find any aneurysms refer to follow up>5cm diameter –increased chance of rupture<5cm –decreased chance of rupture

Symptomatic aneurysms of any size = Emergency!!

Operative mortality of

unruptured

aneurysm is 5%

Operative mortality of ruptured aneurysm is >50%

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Syphilitic aneurysm

Occurs in 3rd stage syphilis

Obliterative

endarteritis

Involvement of

vasa

vasorum of the aortaResults in ischaemic medial injuryLeading to aneurysmal

dilation of the aorta and aortic annulus- eventually

valvular

insufficiency24Slide25

Morphology

Home work25Slide26

Aortic Dissection (Dissecting

haematoma)It is a catastrophic illness characterized by dissection of blood between and along the laminar planes of the media

With the formation of a blood- filled channel within the aortic wall

that often ruptures outwards, causing massive

haemorrhage

/ cardiac

tamponade

May or may not associated with marked dilatation of the aorta 26Slide27

Aortic Dissection

Prominent cause of sudden deathViolation of intima that allows blood to enter media and dissect b/w

intimal

and adventitial layers

Common site is ascending aorta at

ligamentum

arteriosumUnusual in the presence of substantial AS, syphilis ( medial scarring obstruct the advancement of dissection) 27Slide28

Common presenting groups

Occurs mainly in 2 groups of patients

Men 40-60 years of age with antecedent HT

( 90% of cases)

Usually younger

Systemic or localized abnormality of connective tissue that affect the aorta

.

Eg: Marfan syndromeIatrogenic- complication of arterial

cannulation

Congenital heart disease

Pregnancy28Slide29

Pathogenesis

HT is the major risk factor for aortic dissectionMedial hypertrophy of the

vasa

vasoum

Pressure related mechanical injury and / or

ischaemic

injuryOther rare causes includeInherited or acquired CT disorders causing abnormalvascular ECM

Marfan

syndrome ( elongated axial bones, lens

subluxation, cardiovascular manifestations)Vit C deficiencyCopper metabolic defects29Slide30

Once the tear has occurred, blood flow under systemic pressure dissects through the media

Fostering progression of the medial haematoma

In some cases, disruption of the

vaso

vasorum

can give rise to an intramural

haematoma without an intimal tear 30Slide31

Clinical Features

The risk and nature of serious complications depend strongly on the level of the aorta affectedMost serious complications with the involvment of aorta from the aortic valve to the arch

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>

85% abrupt, severe pain in chest or b/w scapula50% ripping or tearingPain in anterior chest –ascending aorta (70%)

Back pain (less common) –descending aorta (63%)

If dissection into carotid classic neurological symptoms

40% with neurologic

sequelae

(ex. paraplegia)

Nausea, vomiting, diaphoresisMost have sense of impending doom32Slide33

Classification

Stanford ClassificationType A ( proximal and dangerous) -involves

Ascending aorta only or

ascending aorta, arch & descending aorta

Type B –involves descending aorta

DeBakey

Classification

Type I –ascending onlyType II –ascending, arch & descending aortaType III –descending only

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Most common cause of death is rupture of the dissection outwards into the body cavity

Retrograde dissection into the aortic root causes disruption of the aortic valvular apparatus

Cardiac

tamponade

Aortic insufficiency

MI

Transverse

myelitis (compression of spinal artery)Critical vascular obstruction( extension of the dissection into the great arteries)34Slide35

The right carotid artery is compressed by blood dissecting upward from a tear with aortic dissection.

Blood may also dissect to coronary arteries. Thus patients with aortic dissection may have symptoms of severe chest pain (for distal dissection) or

may present with findings that suggest a stroke (with carotid dissection) or

myocardial ischemia (with coronary dissection

).

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An aortic dissection may lead to

hemopericardium when blood dissects through the media proximally. Such a massive amount of hemorrhage can lead to cardiac

tamponade

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Morphology

In spontaneous dissection

Intimal

tear marking the point of origin( found in the ascending aorta within 10cm of the aortic valve)

The dissection can extend along the aorta proximally towards the heart and distally

Haematoma

spreads characteristically along the laminar planes of the aorta between the middle and the outer thirds

It often ruptures out causing massive haemorrhage

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There is a tear (arrow) located 7 cm above the aortic valve and proximal to the great vessels in this aorta with marked atherosclerosis.

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Some times rupture into the lumen creating a second or distal

intimal tearNew vascular channel within the media of the aorta ( double – barreled

aorta with

false channel).

With time false channel become

endothelialized

-

chronic dissection.39Slide40

This aorta has been opened longitudinally to reveal an area of fairly limited dissection that is organizing.

The red-brown thrombus can be seen in on both sides of the section as it extends around the aorta. The intimal

tear would have been at the left.

This creates a "double lumen" to the aorta.

This aorta shows severe atherosclerosis which, along with cystic medial necrosis and hypertension, is a risk factor for dissection.

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Microscopically,

the tear (arrow) in this aorta extends through the media, but blood also dissects along the media (asterisk).

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In most cases, no specific

causual pathology can be identified in the aortic wallMost pre-existing

histologically

detectable lesion is cystic medial degeneration

will be seen in

Marfans

and HT

Elastic tissue fragmentationSeparation of elastic and fibromuscular elements of the tunica media by small cleft like or cystic spaces filled with amorphous extracellular materialsInflammation is characteristically absent.

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