SM 137a - Peripheral Vascular Disease Flashcards
What congenital syndromes are associated with abdominal aortic aneurysm?
Marfan syndrome (Fibrilin-1 defect)
Type IV Ehlers-Danlos syndrome (Type III procollagen defect)
Describe the presentation of a patient with aortic dissection
- Severe, excruciating pain in the anterior chest and back
- Malperfusion syndrome
- Stroke
- Intestinal ischemia
- Lower extremity ischemia
- Paralysis
- Cardiac tamponade (type A)
- Coronary ostia compromise (type A)
- Hypotension/shock
What is TEVAR?
What does it usually repair?
TEVAR = thoracic endovascular aortic repair
Typically repairs aortic dissection
What are the possible presentations of abdominal aortic aneurysm?
Asymptomatic
Abdominal or back pain
Distal emboli
Rupture (pain, hypotension, pulsatile mass)
What are the major risk factors for peripheral aterial disease (PAD)?
HASH-FAD
- Hypertension
- Age >65 years
- Smoking
- Hyperlipidemia
- Family history
- Atherosclerosis (known in another vasclar bed)
- Diabetes
Males are ____ times as likely to have an abdominal aortic aneurysm than females
Males are 2-6 times as likely to have an abdominal aortic aneurysm than females
Type B aortic dissections are __________ to the left subclavian artery
Type B aortic dissections are Distal to the left subclavian artery
Patient population: 50+ years old, initial clinical presentation of peripheral arterial disease (PAD)
What fraction of these patients present with critical limb ischemia (aka CLTI)? (Box D)
1-3%
What complications of type B aortic dissection would create a need for emergency surgery?
- Paraplegia
- Renal failure
- Renal vascular hypertension
- Bowel gangrene
- Leg ischemia
- Intestinal ischemia
- Rupture
As an aneurysm gets larger, the risk of it rupturing increases.
Which law explains this?
La Place’s Law
Increased diameter and pressure increase the wall pressure, thus increasing the risk of rupture
A patient with an abdominal aortic aneurysm has increased circulating levels of MMP-9
What do you recommend for treatment?
Increased levels of MMP-9 indicate a large, expanding aneurysm.
In this case, you will most likely want to repair the aneurysm surgically
____% of all abdominal aortic aneurisms are genetic
15-25% of all abdominal aortic aneurisms are genetic
Patient population: 50+ years old, initial clinical presentation of peripheral arterial disease (PAD)
Of the patients who do not have critical limb ischemia initially (97-99%), list the 5-year outcomes for limb mortality for:
Stable claudication (Box H):
Worsening claudication (Box I):
Critical limb ischemia (Box J):
Stable claudication (Box H): 70-80%
Worsening claudication (Box I): 10-20%
Critical limb ischemia (Box J): 5-10% - See 1 year outcomes for CLI
Patient population: 50+ years old, initial clinical presentation of peripheral arterial disease (PAD)
Of the patients who do not have critical limb ischemia initially (97-99%), list the 5-year outcomes for CV morbidity and mortality:
Non-fatal CV event (MI or stroke) (Box K):
Mortality (Box L):
Non-fatal CV event (MI or stroke) (Box K): 20%
Mortality (Box L): 10-15%
Note: 75% of these mortalities are from CV causes
What are the risk factors for initiation of an abdominal aortic aneurysm?
Genetics (connective tissue disorders)
Gender
Ethnicity
Age
People with peripheral arterial disease have a ___ fold increased risk of mortality
People with peripheral arterial disease have a 2-3 fold increased risk of mortality
Patient population: 50+ years old, initial clinical presentation of peripheral arterial disease (PAD)
Of the patients who present with critical limb ischemia (1-3%) list the 1-year outcomes for the following:
Alive with 2 limbs (Box E):
Amputation (Box F):
Mortality (Box G):
Alive with 2 limbs (Box E): 45%
Amputation (Box F): 30%
Mortality (Box G): 25%
What are the risk factors for progression of an abdominal aortic aneurysm?
Smoking
Hypertension
Atherosclerosis
What life-threatening sequale can arise from type A aortic dissection?
Aortic valve insufficiency
Occlusion of coronary vessels
Rupture into pericardium
People between ____ and ____ years old are more likley to have a type A aortic dissection
People between ____ and ____ years old are more likley to have a type B aortic dissection
People between 50** and **60 years old are more likley to have a type A aortic dissection
People between 60 and 70 years old are more likley to have a type B aortic dissection
People with peripheral aterial disease have a _____ fold increase in their chance of dying from coronary artery disease
People with peripheral aterial disease have a 4-5 fold increase in their chance of dying from coronary artery disease
Type A aortic dissections are __________ to the left subclavian artery
Type A aortic dissections are proximal to the left subclavian artery
What are the indications for surgical treatment of an abdominal aortic aneurysm?
The aneurysm should be repaired if it is…
- Large (>5.5 cm)
- Rapidly expanding (>0.5 cm/year)
- Symptomatic
- Ruptured - Emergency repair!
What sources of MMPs are relevant to aortic aneurysm?
- Vascular smooth muscle cells
- Fibroblasts
- Inflammatory cells
- Endothelial cells surrounding the vasa vasorum
What is EVAR?
What does it typically repair?
Endovascular AAA repair
(Abdominal aortic aneurysms)
What are the 3 central themes that drive the pathophysiology of abdominal aortic aneurysms?
-
Inflammation:
Inflammatory cells release cytokines and activate MMPs -
Disruption of connective tissue architecture with loss of elastin:
MMPs degrade collagen and elastin -
Medial thickening:
Smooth muscle cells - increased apoptosis, decreased density, impaired proliferation
How can circadian pattern paly a role in the pathophysiology of aortic dissection?
In the morning…
- Increased sympathetic activity
- Increased BP, HR
- Increased shear forces
- Increased BP, HR
- Increased platelet activation, fibrinogen, coagulation factor
- Hyperoagulability + weakened arterial wall
- Dissection
- Hyperoagulability + weakened arterial wall
- Decreased tissue plasminogen activator (tPA)
- Hypofibrinolysis
All of the above lead to increased risk of aortic dissection
Describe the pathophysiology of aortic dissection
- Hypertenstion is usually implicated!
- -> Medial degeneration
- -> Intimal thickening
- Fibrosis
- Calcifications
- Fatty acid deposition
- Adventitial fibrosis
Also…
- Inherited connective tissue disorders
- Association with cocaine use
- Circadian pattern (more sympathetic and platelet activity in the mornings)
What is the mortality of untreated aortic dissection within…
6 hours:
24 hours:
1 week:
6 hours: 22.7%
24 hours: 50%
1 week: 68%
How should type B aortic dissections be treated?
- If complications are life threatening:
- Emergency surgery
- If complications are not life-threatening:
- Use medical management
- Decrease blood pressure
- Decrease contractility
- Decrease HR
- Pain control
- Use medical management
Which two types of MMP are relevant to aortic aneurysm?
-
MMP-2
- Substrates = collagen, gelatin, elastin
- Levels increase in a small, stable aneurysm
-
MMP-9
- Main substrate = elastin
- Levels increase in large, expanding aneurysms
- Tissue and circulating MMP-9 are proportional to aneurysm size
Which type of aortic dissection is most life-threatening?
Why?
Type A aortic dissections are most life-threatening because they may involve the heart
- Require emergency surgical treatment
- May affect the aortic valve
- -> Sudden valvular incompetence, death
- May rupture into the pericardium
- -> Death
What are the 3 general types of peripheral arterial disease?
Which are classified as “chronic limb-threatening ischemia (CTLI),” aka “critical limb ischemia (CLI)”?
- Claudication: Pain with walking
- Rest pain: Pain in the feet at rest
- Tissue loss/ulceration/gangrene
2 and 3 are classified as CTLI/CLI
Besides aorta, what are other vessels that may develop an aneurysm?
- Popliteal (2nd most common location)
- Subclavian
- Femoral (99% occur in men)
- Hand (usually caused by trauma)
What are MMPs?
MMPs = Matrix metalloproteinases
- Zinc-dependent enzymes
- Secreted as zymogens (proenzymes)
- Activated by inflammatory cytokines
- Degrade collagen and elastin
What is a mycotic aneurysm?
An aneurysm due to infection
Patient population: 50+ years old, initial clinical presentation of peripheral arterial disease (PAD)
What fraction of these patients are are asymptomatic? (Box A)
A: 20-50%
Patient population: 50+ years old, initial clinical presentation of peripheral arterial disease (PAD)
What fraction of these patients present with typical caudication? (Box C)
10-35%
How should type A aortic dissections be treated?
Emergency surgery
What defines an abominal aortic aneurysm?
Enlargement of the aortic diameter to 1.5x its normal diameter
(Typically >3cm total for the aorta)
Patient population: 50+ years old, initial clinical presentation of peripheral arterial disease (PAD)
What fraction of these patients present with leg pain other than typical caudication or critical limb ischemia? (Box B)
B: 30-40%
What type of genetic disorders predispose an individual to aortic dissection?
Connective tissue disorders; usually implicated if a young person has an aortic dissection
(ex: Marfan’s syndrome)
What is the most common cause of peripheral arterial disease (PAD)?
Atherosclerosis
What is an aortic dissection?
A tear in the edothelium of a major artery that causes blood to course through a small opening, into the media of a vessel
The layers then split over an extended length, creating a false lumen between the intima and the media
What causes aneurysms to be pathologic?
If they rupture or thrombose/embolize
Rupture usually occurs in body cavities
Thrombosis/embolizm usually occurs in extremities
List the possible etiologies of abdominal aortic aneurysm
- Atherosclerotic (90%)
- Infectious: Mycotic aneurysm
- Inflammaotry
- Congenital syndromes
- Post-stenotic
- Pseudoaneurysm
- Congenital anatomy
