2. Structure and function of blood
vessels
• 5 main types
– Arteries – carry blood AWAY from the heart
– Arterioles
– Capillaries – site of exchange
– Venules
– Veins – carry blood TO the heart
4. Structure
• Tunica interna (intima)
– Inner lining in direct contact with blood
– Endothelium continuous with endocardial lining of heart
– Active role in vessel-related activities
• Tunica media
– Muscular and connective tissue layer
– Greatest variation among vessel types
– Smooth muscle regulates diameter of lumen
• Tunica externa
– Elastic and collagen fibers
– Vasa vasorum
– Helps anchor vessel to surrounding tissue
6. Arteries
3 layers of typical blood vessel
– Thick muscular-to-elastic tunica media
– High compliance – walls stretch and expand in
response to pressure without tearing
– Vasoconstriction – decrease in lumen diameter
• Vasodilation – increase in lumen diameter
7. Veins
• Structural changes not as distinct as in arteries
• In general, very thin walls in relation to total
diameter
• Same 3 layers
• Tunica interna thinner than arteries
• Tunica interna thinner with little smooth muscle
• Tunica externa thickest layer
• Not designed to withstand high pressure
Valves – folds on tunica interna forming cusps
• Aid in venous return by preventing backflow
9. Aneurysms
• Localized abnormal dilatation of blood
vessel or the wall of the heart that may be
congenital or acquired.
• True aneurysm: an aneurysm is bounded by
arterial wall components or the attenuated
wall of the heart.
• Atherosclerosis, Syphilitic & congenital
vascular aneurysms & left ventricular
aneurysm that can follow MI.
10. Aneurysm
• False/Pseudo aneurysm: it is the breach in the
vascular wall leading to an extravascular
hematoma that freely communicates with the
intravascular space ( “pulsating hematoma”).
OR
• Having fibrous wall & occuring often from
trauma to the vessel.
• Post-myocardial infarction rupture that has
been contained by a pericardial adhesion.
11. Aneurysms
Depending upon the shape classified as
• Fusiform having slow spindle shaped dilatation.
• Saccular : having large spherical outpouching.
• Dissecting: arises when blood enters the wall of artery, as a hematoma
dissecting b/w its layers.
• Cylindrical: with a continuous parallel dilatation.
• Serpentine or varicose: Has tortuous dilatation of vessel.
• Racemose or circoid: having mass of inter communicating small
arteries & veins.
• Berry aneurysm: small dilatations ( circle of willis in the base of brain)
• Complications:
– Thrombosis
– Embolism
– Rupture
15. Pathogenesis : aneurysms
1. The intrinsic quality of the vascular wall CT is poor.
Example:
Marfan syndrome: defective synthesis on protein
fibrillin- weakning of elastic tissue.
Ehlers –Danlos syndrome: defective type III
collagen synthesis.
loeys- dietz syndrome: mutations in TGF-beta
receptors- defective synthesis of elastin & collagens
I & II.
16. Pathogenesis : aneurysms
2. The balance of collagen degradation &
synthesis is altered by inflammation &
associated proteases
3. Vascular wall is weakened through loss 9of
smooth muscle cells or synthesis of
noncollagenous or nonelastic extracellular
matrix.
19. Abdominal aortic aneurysm ( AAA)
• Occuring as a consequences of atherosclerosis.
• Abdominal aorta & common iliac arteries.
• Common in men & in smokers.
• Rarely developing before age 50.
• Positioned below renal arteries & above
bifurcation of aorta.
• Saccular/ fusiform : 15cm in diameter & 25cm
in length.
20. Abdominal aortic aneurysm ( AAA)
• There is severe complicated atherosclerosis,
destruction & thinning of aortic media, containing
bland, laminated ,poorly organized mural thrombosis.
• Variants of AAA
1. Inflammatory AAA: younger patients, back pain,
elevated inflammatory markers (increased C-reactive
protein)
• Lymphoplasmacytic inflammation with many
macrophages. Periaortic scarring.
• Cause: localized immune response.
21. Mycotic aneurysms
• Infection of major artery that weakens its wall
give rise to mycotic aneurysm.
• Originate either
1.From embolization & arrest of septic embolus
at some point in the vessel( as a complication
of infective endocarditis)
2.As an extension of an adjacent suppurative
process
3.By circulating organisms directly infecting the
arterial wall.
24. Syphilitic ( luetic aneurysms)
• cardiovascular syphilis causes arteritis:
syphilitic aortitis and cerebral arteritis.
• The obliterative endarteritis characteristic of
the tertiary syphilis ( lues) , predilection for
small vessels.
• Syphilitic involvement of vasa vasorum of
thoracic aorta can lead to aneurysmal
dilatation.
26. Syphilitic ( luetic aneurysms)
• Syphilitic aneurysm Occurs in 3 rd stage
syphilis –
• Obliterative endarteritis
• Involvement of vasa vasorum of the aorta –
Results in ischaemic medial injury
• Leading to aneurysmal dilation of the aorta
and aortic annulus- eventually valvular
insufficiency.
27. Aortic Dissection (Dissecting
hematoma)
• 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 hemorrhage /
cardiac tamponade.
• May or may not associated with marked
dilatation of the aorta.
28. Aortic Dissection
• Aortic Dissection – Prominent cause of sudden
death
• Violation of intima that allows blood to enter
media and dissect b/w intimal and adventitial
layers
• Common site is ascending aorta at ligamentum
arteriosum .
• Unusual in the presence of substantial
Atherosclerosis, syphilis ( medial scarring
obstruct the advancement of dissection)
29. Aortic Dissection
• Occurs mainly in 2 groups of patients
1. Men 40-60 years of age with antecedent HT ( 90% of
cases)
2. Usually younger Systemic or localized abnormality
of connective tissue that affect the aorta. Eg: Marfan
syndrome
3.Iatrogenic- complication of arterial cannulation
4.Congenital heart disease
5.Pregnancy
30. Pathogenesis: Aortic Dissection
• HT is the major risk factor for aortic dissection
• Medial hypertrophy of the vasa vasorum asso. With
degenerative changes such as loss of medial smooth muscle
cells & disorganized ECM.
• Pressure related mechanical injury and / or ischemic injury
Other rare causes include
• Inherited or acquired CT disorders causing abnormal vascular
ECM
Marfan syndrome ( elongated axial bones, lens subluxation,
cardiovascular manifestations)
Vit C deficiency Copper metabolic defects
31. Aortic Dissection
• Once the tear has occurred, blood flow under
systemic pressure dissects through the media
Fostering progression of the medial hematoma.
• In some cases, disruption of the vaso vasorum
can give rise to an intramural hematoma
without an intimal tear.
33. Aortic Dissection
• Clinical Features
• The risk and nature of serious complications
depend strongly on the level of the aorta
affected.
• Most serious complications with the
involvement of aorta from the aortic valve to
the arch .
34. Aortic Dissection
• 85% abrupt, severe pain in chest or b/w scapula –
50% ripping or tearing – Pain 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, diaphoresis – Most have sense
of impending doom
35. Classification: Aortic Dissection
• Stanford Classification
• Type A ( proximal and dangerous) -involves –
Ascending aorta only or – ascending aorta, arch &
descending aorta
• Type B –involves descending aorta
DeBakey Classification
Type I –ascending only
Type II –ascending, arch & descending aorta
Type III –descending only
36. Aortic Dissection
• 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)
37. Varicose veins
• Abnormal diffuse dilatation of veins.
• Lower limbs- common
• Congenital or acquired
• Pathogenesis:
– Damage to valves
– Stagnation
– Increased pressure dilatation.
• Chronic ulcers.
39. Vasculitides
• Vasculitides = Inflammation of Blood Vessels
• Present with Non-Specific/ systemic/Vague complaints
• Fever, Myalgia, Artharlgia, Malaise, etc.,
Types : Based on
– Size of Vessels involved
– Site of involvement
– Characteristic Features
40. Pathogenic Mechanisms
Immune –
1. Immune complex : Hypersensitivity (to Drugs),
Following Viral Infections (PAN & HBV)
2. ANCA Positive
• (Anti Neutrophil Cytoplasmic Antibodies) C- ANCA
(Ab Against Proteinase -3) :Wegener's
– P- ANCA ( Ab against MPO) : mPAN, Chaurg –
Straus
3. Anti – Endothelial Cell antibodies: SLE, Kawasaki’s
4. Autoreactive T cells.
Infectious –
• Less Common, Direct Trauma is the cause, can be
Bacterial or fungal
41. Giant cell ( Temporal) arteritis
• Systemic Vasculitis: chronic
inflammatory disorder of large to
small-sized arteries.
• Sites : Temporal ( Head ache &
Facial Pain), Vertebral, Ophthalmic
( Blindness), Aorta ( Aneurysm)
• Age, Sex & Ethnicity :
>50 yrs, M=F, Nordic people
• Clinical :Facial Pain & Headache,
Diplopia & Blindness (most
dangerous, Sudden, permanent)
• Pathology / Morphology : intimal
thickening – reduce luminal
diameter.
Granulomas in vessel walls, Giant
cells, Segmental involvement,
Fragmentation of Internal Elastic
Lamina (IEL)
• Diagnosis: Biopsy is important
Treatment: Steroids save vision
42. Takayasu ( Pulse less )
Arteritis
• Systemic Vasculitis : granulomatous vasculitis of
Medium and large size vessels
• Sites :Aorta ( Aneurysm), Temporal
( Head ache & Facial Pain), Vertebral, Ophthalmic
( Blindness),
• Age, Sex & Ethnicity
<40 yrs., F>M, Japanese, HLA (A24, B52, DR2)
• Clinical :Pulses Weak & Low BP in Hands ( Just
opposite to Coarction of Aorta)
• Pathology / Morphology : transmural fibrous thickening
of aorta.
Granulomas in vessel walls, Giant cells, Fibrosis and
Lymphocytic infiltration
• Diagnosis :Biopsy
Treatment :Steroids
• Complications :MI, Aortic Regurgitation
43. Polyarteritis Nodosa (PAN)
• Systemic Vasculitis of Small or Medium -sized
vessels
• Sites: Kidneys (not the Glomerular capillaries),
Heart, Liver, and GIT (NOT LUNGS)
• Age, Sex & Ethnicity :
Young Adults, M>F , no special risk groups
• Clinical :
Ulcers, Infarcts, Hemorrhages, HBsAg Positive
• Clinical course : Relapses & Remissions
• Pathology / Morphology :segmental transmural
necrotising inflammation.
acute (inflammation, Fibrinoid Necrosis,
Thrombosis), Chronic (nodularity, Fibrosis )
• Diagnosis: Biopsy is important, No ANCA
Positive
• Treatment :corticosteroids and
Cyclophosphamide
• Complications : Renal Failure, CNS lesions
Idiopathic PAN
Cutaneous forms of PAN
PAN asso. with chronic hepatitis.
44. PAN
• Small & Medium size
Vessels
• Different stages of disease
in same or different vessels
• HBsAg Positive
• ANCA Negative
• Capillaries (Pulmonary,
Glomerular) not involved,
• Large infarcts seen
• Bad prognosis
4. mPAN( micro)
• Smallest vessels( Arterioles,
capillaries, Venules)
• Same stage of disease in all
vessels
• Negative
• P-ANCA Positive
• Involved (Necrotizing
Glomerulonephritis,
Hemoptysis)
• No Large infarcts
• Better Prognosis
45. Kawasaki Disease
Muco Cutaneous Lymph node syndrome
• Systemic Vasculitis :of Small &
Medium size vessels
• Sites :coronary, cutaneous vessels
• Age, Sex & Ethnicity : Very
young (<4yrs. Age), North
America, Japan
• Clinical : Fever, Muco
(conjunctival, oral erythema,
erosions), cutaneous (erythema of
palms, soles, & Skin rash), Lymph
node syndrome ( cervical)
• Clinical course :spontaneous
Remissions in most of them
• Treatment :aspirin,
Immunoglobulins
• Complications: coronary
aneurysms
Acute febrile, usually self-limited
illness of infancy & childhood ( 80%
are 4 yrs old or younger)
