Fung: Vascular Pathology Flashcards
Occur in cerebral vessels
Majority occur sporadically
Some are genetic
AD polycystic kidney disease, Ehler-Danlos syndrome, NF1, Marfan syndrome
developmental (berry) aneurysms
What diseases are associated with berry aneurysms?
polycystic kidney disease
Ehler-Danlos syndrome
Marfan syndrome
What are two major risk factors for berry aneurysms?
cigarette smoking
hypertension
Are berry aneurysms really congenital?
no, they are referred to as congenital but they actually develop over time
Small direct connections between arteries and veins that bypass capillaries
atriovenous fistulas
Why do atriovenous fistulas occur?
developmental defects
rupture of arterial aneurysm into an adjacent vein
penetrating injuries that pierce arteries and veins
inflammatory necrosis of adjacent vessels
iatrogenic (consequence of medical treatment)
Focal irregular thickening of the walls of medium and large muscular arteries
Results in luminal stenosis
fibromuscular dysplasia
**occurs most frequently in young women
Localized abnormal dilation of a blood vessel or the heart
Congenital or acquired
Aneurysms
Involves an intact attenuated arterial wall or thinned ventricular wall
True aneurysm
**ex: Atherosclerotic
Syphilitic
Congenital
Ventricular following transmural infarction
Defect in the vascular wall leading to an extravascular hematoma that freely communicates with the intravascular space
False aneurysm, or pseudo-aneurysm
**Ex: ventricular rupture with pericardial adhesion
Differentiate between a saccular and fusiform true aneurysm
a saccular aneurysm is going to involve spherical outpouchings of only a portion of the vessel (usu 5-20cm in diameter)
a fusiform aneurysm is a diffuse, circumferential dilation along a vascular segment (can be up to 20cm in diameter); these aneurysms often involve extensive portions of the aortic arch, abdominal aorta, and iliac arteries
T/F: Any process that causes weakening of the vessel wall can cause aneurysm formation
true!
**aneurysms can be sporadic or due to connective tissue disease
Defect in fibrillin which can lead to aneurysm formation
Marfan syndrome
Defect in the synthesis or structure of fibrillar collagen; can lead to aneurysm formation
Ehlers-Danlos syndrome
Altered collagen cross-linking; can lead to aneurysm formation
Vit C deficiency
Defect in elastin, collagen I, and III; can lead to aneurysm formation
Loeys-Dietz syndrome
How do aneurysms form?
inflammation alters the balance of synthesis and destruction of collagen
increased matrix metalloproteases degrade the ECM
or
loss of smooth muscle cells or proliferation of non-collagenous/non-elastic extracellular matrix
**thickening of the intima decreases diffusion of oxygen and nutrients to the media causing the media to degrade
Two of the most important predisposing factors for aneurysm formation?
atherosclerosis
hypertension
Other causes of aneurysm formation?
congenital defects
infections due to embolization, direct extension or circulation of organisms
Where are atherosclerotic aneurysms most likely to occur?
abdominal aorta
**seen in male smokers >60 yo with HTN
What is one major influence in the formation of an abdominal aneurysm?
increased matrix metalloproteinase
**also, athersclerosis increases the diffusion barrier to the media, resulting in atrophy and weakening of the vessel wall
Name these two flavors of aneurysms:
- dense periaortic fibrosis containing abundant lymphocytes, plasma cells and macrophages
- due to circulating microorganisms that destroys the media
- inflammatory type
2. mycotic type
What are some clinical consequences if you have an abdominal aortic aneurysm?
rupture w potentially fatal hemorrhage (hypotension, pulsatile abdominal mass, flank pain)
impinging on adjacent structures
obstruction of some branch vessel
embolism from atheroma or a thrombus
This type of aneurysm is most commonly associated with hypertension; classically seen in tertiary syphilis
thoracic aneurysm
**tree bark appearance of the aorta
List 4 signs and symptoms of a thoracic aneurysm
- cough due to pressure on recurrent laryngeal nerve
- bone pain
- aortic valve dilation with insufficiency
- encroachment on lungs/airways, esophagus, and mediastinal structures
What is this?
Blood splays apart the laminar planes of the media to form a blood filled channel within the vessel wall
May or may not be associated with vessel dilation
dissection
Who gets dissections?
men 40-60 yo with hypertension
younger pts with abnormalities of the aorta
iatrogenic (complication of medical procedure)
Are dissections usu seen in cases of athersclerosis?
no, because in atherosclerosis there is fibrosis of the media, which would make it less likely for blood to splay apart the media
What is the major risk factor for dissection?
hypertension!!
**hyaline arteriosclerosis of the vasa vasorum –>cystic medial degeneration
In which inherited/acquired tissue disorders is dissection more common?
Marfan syndrome
Ehler-danlos syndrome
Vit C deficiency
**cystic medial necrosis due to connective tissue dysfunction
What is the most frequent histologically detectable lesion in patients with dissection?
cystic medial degeneration
Type A dissections are proximal lesions, and involve which parts of the aorta?
the ascending aorta only (DeBakey II)
or
both the ascending and descending aorta (Debakey I)
Type B dissections are distal lesions and involve which part of the aorta?
They begin distal to the subclavian artery and don’t involve the ascending aorta (DeBakey III)
General term for vessel wall inflammation
Clinical features depends on the vascular bed affected and can affect vessels of any organ or any size
vasculitis
What are the two most common pathogenic mechanisms for vasculitis?
- immune-mediated inflammation
2. direct invasion of the vascular walls by infectious agents
Which vessels are affected in large vessel vasculitis?
aorta
large branches to extremities, head, and neck
Which vessels are affected in medium vessel vasculitis?
main muscular/visceral arteries and their branches
Which vessels are affected in small vessel vasculitis?
arterioles, capillaries, venules