11/2 Diseases of Aorta - Corbett Flashcards
gross anatomy of the aorta
microscopic anatomy (layers)
- major blood conduit from LV
- diameter decreases moving from thoracic → abdominal/infra-renal portions
- medial elastin layers, overall elastin content, and collagen content decline from proximal to distal
three layers:
- intima: endothelial cells on top of internal elastic lamina
-
media: SMCs and ECM of colagen (strength) and elastic fibers (flexibility)
* elastic lamellae allow aorta to withstand pressures and evenly distribute flow to extremeties - adventitia: collagen, perivascular nerves, vasa vasorum
fibrillin-1
deficiency of fibrillin-1?
fibrillin-1 is a glycoprotein that helps to maintain the structural integrity of the aortic wall and valve leaflets
- tethers VSM cells to a matrix of elastin and collagen
fibrillin-1 deficiency leads to VSM cell detachment from elastin and collagen
- induces apoptosis and loss of ECM structural integrity
- MARFAN SYNDROME
HTN as a normal consequence of aging
explain
elastin component of the aorta degenerates over time as a normal conseq of aging
- eventually, collagen >>> elastin
- aorta stiffens
- SYSTOLIC BP RISES bc walls are less distensible! → higher systolic pressure
coarctation of aorta
comorbidities
in utero issues?
other congenital heart defects
- VSD, AV canal defects
- **bicuspid aortic valve**
Turner Syndrome
coarctation does NOT cause problems in utero!
- 2/3 of combined cardiac output flows through PDA into desc thoracic aorta (bypassing site of constriction at isthmus)
coarctation of the aorta
pathophysiology
- increased afterload →
- incr LV wall stress
- compensatory LVH
- development of aortic collaterals → “notching of ribs”
- development of hypertension
- mechanical obstruction
- renin-angiotensin-mediated humoral mechs
classic findings of coarctation of aorta:
older child, adult
- systolic HTN in upper extremities
- reduced systolic BP in lower extremities (> 20mmHg)
- radial artery to femoral pulse delay
other sx and signs
- incidental HTN (majority of adult patients detected thsi way)
- headache, fatigue, chest pain, leg weakness
- MURMUR
- systolic/holosystolic
- left infra-clavicular area or under left scapula
- bicuspid aortic valve occurs in 30% of adults
- systolic murmur following ejection click
classic findings of coarctation of aorta:
infant
- congestive heart failure
- tachycardia, poor feeding, shock
- differential cyanosis
what do these findings indicate?
- fixed splitting of S2
- radial to femoral pulse delay
- cont machine-like murmur below left clavicle
- capillary pulsations
- blowing decrescendo diastolic murmur over LSB
- ASD
- coarctation of aorta
- patent ductus arteriosus
- aortic regurgitation
- aortic regurgitation
bicuspid aortic valve
basics
associations/risks
male predominance 3:1
35% of affected develop complications:
- aortic stenosis and regurg
- endocarditis
- asc aortic aneurysm (26%)
- aortic dissection (8x)
>50% of BAV patients have dilated aortic root
- ARD increases risk of acute aortic dissection/rupture
bicuspid aortic valve:
clinical presentation
aortic stenosis is most common manifestation of disease (75% of pts have it)
- progressive fibrocalcific stenosis of valve requiring intervention and presenting at YOUNG AGE
aortic regurg (20%)
aortic dissection
endocarditis
aortic dissection
what is it?
what causes it?
damage to intima, causing secondary damage to media
- intima tears, allows high pressure blood to gain access to media
- blood travels within media (both prox and dist)
what causes aortic dissection?
DAMAGE TO AORTIC WALL
- HTN + atherosclerosis → necrosis and fibrosis of media = cystic medial degeneration
- intimal tear develops → blood enters media
- “false lumen” is created by high pressure, can extend to outer aspect of media and propagate prox or dist
classification of aortic dissection
where do aortic dissections classically present?
Type A dissections : proximal/involves arch of aorta
- usually require surgical repair
- aka DeBakey I and DeBakey II
Type B dissections : distal/no arch involvement
- can be managed medically (unless leaking or ruptured)
- aka DeBakey III
*classically, aortic dissection begins in ascending aorta (2x as common as desc aortic dissection)
aortic dissection etiology
- chronic arterial HTN
- smoking
- hyperlipidemia
- cocaine use
- pregnancy (usually with eclampsia)
- trauma
-
genetic factors
- Marfan Syndrome
- Enler-Danlos Syndrome
- Turner Syndrome
- Bicuspid Aortic Valve
aortic dissection: clinical presentation of acute dissection
presentation
exam findings
chest pain of severe intensity that occurred suddenly
absence of SUDDEN ONSET of pain = strong negative predictive value
key Qs:
- quality (sharp/tearing?)
- radiation of pain (back/scapula)
- intensity of pain at onset (10/10)
key exam findings
- hypertensive on presentation
- murmur of aortic regurg
- pulse deficits (if dissection extends to subclavians…could end up knocking out extremity pulse! upper limb ischemia)
- less common: neuro deficits, hypotension, renal failure, mesenteric ischemia, limb ischemia
catastrophic dissection
three types
three types
- free rupture
- occlusion of coronary ostia → MI
- proximal rupture into pericardium
results in death
aortic dissection:
making diagnosis
sudden onset of severe chest pain AND
- back pain
- abd pain
- syncope
- stroke
- MI
- limb ischemia
- mesenteric ischemia
need advanced imaging to exclude
- rule out high risk conditions
- Marfan’s Syndrome
- known aortic valve disease (ex. BAV)
- family hx
- check for high risk pain features
- abrupt onset
- severe
- “ripping/tearing”
- check for high risk exam features
- perfusion deficit
- murmur of aortic regurg
- hypotension
aortic aneurysmal disease
definition
most occur in infrarenal abdominal aorta (but can occur anywhere!)
- most common complication: RUPTURE
aneurysm: localized or diffuse dilation of an artery with diameter at least 50% greater than normal
- abd aorta aneurysm = > 3cm
pathophysiology of aneurysms
over age of 65:
degradation of aortic medial connective tissue
- increased MMP activity → degrades media
ischemic injury of media
- atherosclerosis
- damage to vasa vasorum
poor quality vascular connective tissue
- nutritional disorders
pathophys of aneurysms (under age 65)
syndromic connective tissue disorders
4 and wahts messed up
- Marfan Syndrome :: fibrillin
- Ehlers-Danlos (vascular) :: Type III Procollagen
- Loeys-Dietz Syndrome :: TGF-beta receptor
- Turner Syndrome :: XO
management of aortic aneurysm
most aneurysms are asymptomatic
- once detected, monitor diameter until critical point reached, after which: surgery
- until surgery: beta blockers, ARB (losartan)
if symptomatic, refer to surgery!
thoracic aortic aneurysms
consistently high proportion of pt with TAA have family hx
- suggests genetic component!
- inherited disease associated with TAA
- Marfan, Ehlers-Danlos, Loeys-Dietz Syndromes
- Turner Syndrome
- bicuspid aortic valve
HOWEVER, most TAA are acquired through
- degenerative disease
- HTN
- smoking
- atherosclerosis
- acquired infection (ex. sphyilis → arteritis of vasa vasorum within media)
- infl conditions (ex. Takayasu ateritis)
abdominal aortic aneurysms
risk/assoc factors
history/phys exam
- environmental risk more important (disease is more likely degenerative)
- risk factors: smoking, COPD, prior aneurysm, CAD, HTN
- hereditary disorders, genetics
AAAs usually asymptomatic until expansion/rupture
- back, flank, abd, groin pain
- occasionally compressive sx (hydronephrosis, duodenal compression)
physical exam findinds are unreliable: typically find a pulsatile abdominal mass
symptoms of AAA rupture
suden onset of abdominal OR back pain + hypotension = ruptured AAA
- groin pain, syncope, paralysis, flank mass
- 80% mortality associated!
physical signs: hypotension, cold/clammy extremities, signs of shock
