By Dr SHomathy 1 Aneurysm It is a localized dilatation of blood vessel or the heart due to a weakening of its wall 2 Classification Aneurysms may be classified by type location ID: 641055
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Slide1
Aneurysms of blood vessels
By Dr. S.Homathy
1Slide2
Aneurysm
It is a localized dilatation of blood vessel or the heart due to a weakening of its wall.
2Slide3
Classification
Aneurysms may be classified
by
type
,
location, the affected vessel. Other factors may also influence the pathology and diagnosis of aneurysms.
3Slide4
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
4Slide5
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.
5Slide6
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.
6Slide7
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.
7Slide8
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
8Slide9
9Slide10
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
10Slide11
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
11Slide12
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).
12Slide13
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
14Slide15
Pathogenesis
15Slide16
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
16Slide17
Secondary risk factors
Obesity High blood pressure High cholesterol
Atherosclerosis
Cardiovascular disease
17Slide18
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
20Slide21
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
21Slide22
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
22Slide23
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%
23Slide24
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
31Slide32
>
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
33Slide34
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
).
35Slide36
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
36Slide37
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
37Slide38
There is a tear (arrow) located 7 cm above the aortic valve and proximal to the great vessels in this aorta with marked atherosclerosis.
38Slide39
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.
40Slide41
Microscopically,
the tear (arrow) in this aorta extends through the media, but blood also dissects along the media (asterisk).
41Slide42
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.
42Slide43
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44