SM 137a - Peripheral Vascular Disease

Question 1

What congenital syndromes are associated with abdominal aortic aneurysm?

Answer 1

Marfan syndrome (Fibrilin-1 defect)

Type IV Ehlers-Danlos syndrome (Type III procollagen defect)

Question 2

Describe the presentation of a patient with aortic dissection

Answer 2

• 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

Question 3

What is TEVAR?

What does it usually repair?

Answer 3

TEVAR = thoracic endovascular aortic repair

Typically repairs aortic dissection

Question 4

What are the possible presentations of abdominal aortic aneurysm?

Answer 4

Asymptomatic

Abdominal or back pain

Distal emboli

Rupture (pain, hypotension, pulsatile mass)

Question 5

What are the major risk factors for peripheral aterial disease (PAD)?

Answer 5

HASH-FAD

• Hypertension
• Age >65 years
• Smoking
• Hyperlipidemia
• Family history
• Atherosclerosis (known in another vasclar bed)
• Diabetes

Question 6

Males are ____ times as likely to have an abdominal aortic aneurysm than females

Answer 6

Males are 2-6 times as likely to have an abdominal aortic aneurysm than females

Question 7

Type B aortic dissections are __________ to the left subclavian artery

Answer 7

Type B aortic dissections are Distal to the left subclavian artery

Question 8

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)

Answer 8

1-3%

Question 9

What complications of type B aortic dissection would create a need for emergency surgery?

Answer 9

• Paraplegia
• Renal failure
• Renal vascular hypertension
• Bowel gangrene
• Leg ischemia
• Intestinal ischemia
• Rupture

Question 10

As an aneurysm gets larger, the risk of it rupturing increases.

Which law explains this?

Answer 10

La Place’s Law

Increased diameter and pressure increase the wall pressure, thus increasing the risk of rupture

Question 11

A patient with an abdominal aortic aneurysm has increased circulating levels of MMP-9

What do you recommend for treatment?

Answer 11

Increased levels of MMP-9 indicate a large, expanding aneurysm.

In this case, you will most likely want to repair the aneurysm surgically

Question 12

____% of all abdominal aortic aneurisms are genetic

Answer 12

15-25% of all abdominal aortic aneurisms are genetic

Question 13

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):

Answer 13

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

Question 14

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):

Answer 14

Non-fatal CV event (MI or stroke) (Box K): 20%

Mortality (Box L): 10-15%
Note: 75% of these mortalities are from CV causes

Question 15

What are the risk factors for initiation of an abdominal aortic aneurysm?

Answer 15

Genetics (connective tissue disorders)

Gender

Ethnicity

Age

Question 16

People with peripheral arterial disease have a ___ fold increased risk of mortality

Answer 16

People with peripheral arterial disease have a 2-3 fold increased risk of mortality

Question 17

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):

Answer 17

Alive with 2 limbs (Box E): 45%

Amputation (Box F): 30%

Mortality (Box G): 25%

Question 18

What are the risk factors for progression of an abdominal aortic aneurysm?

Answer 18

Smoking

Hypertension

Atherosclerosis

Question 19

What life-threatening sequale can arise from type A aortic dissection?

Answer 19

Aortic valve insufficiency

Occlusion of coronary vessels

Rupture into pericardium

Question 20

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

Answer 20

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

Question 21

People with peripheral aterial disease have a _____ fold increase in their chance of dying from coronary artery disease

Answer 21

People with peripheral aterial disease have a 4-5 fold increase in their chance of dying from coronary artery disease

Question 22

Type A aortic dissections are __________ to the left subclavian artery

Answer 22

Type A aortic dissections are proximal to the left subclavian artery

Question 23

What are the indications for surgical treatment of an abdominal aortic aneurysm?

Answer 23

The aneurysm should be repaired if it is…

• Large (>5.5 cm)
• Rapidly expanding (>0.5 cm/year)
• Symptomatic
• Ruptured - Emergency repair!

Question 24

What sources of MMPs are relevant to aortic aneurysm?

Answer 24

• Vascular smooth muscle cells
• Fibroblasts
• Inflammatory cells
• Endothelial cells surrounding the vasa vasorum

Question 25

What is EVAR? What does it typically repair?

Answer 25

Endovascular AAA repair | (Abdominal aortic aneurysms)

Question 26

What are the 3 central themes that drive the pathophysiology of abdominal aortic aneurysms?

Answer 26

1. **Inflammation**: Inflammatory cells release cytokines and activate MMPs 2. **Disruption of connective tissue architecture with loss of elastin**: MMPs degrade collagen and elastin 3. **Medial thickening**: Smooth muscle cells - increased apoptosis, decreased density, impaired proliferation

Question 27

How can circadian pattern paly a role in the pathophysiology of aortic dissection?

Answer 27

In the morning... * Increased sympathetic activity * Increased BP, HR * Increased shear forces * Increased platelet activation, fibrinogen, coagulation factor * Hyperoagulability + weakened arterial wall * Dissection * Decreased tissue plasminogen activator (tPA) * Hypofibrinolysis All of the above lead to increased risk of aortic dissection

Question 28

Describe the pathophysiology of aortic dissection

Answer 28

* 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)

Question 29

What is the mortality of untreated aortic dissection within... 6 hours: 24 hours: 1 week:

Answer 29

6 hours: **22.7%** 24 hours: **50%** 1 week: **68%**

Question 30

How should type B aortic dissections be treated?

Answer 30

* 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

Question 31

Which two types of MMP are relevant to aortic aneurysm?

Answer 31

* **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**

Question 32

Which type of aortic dissection is most life-threatening? Why?

Answer 32

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

Question 33

What are the 3 general types of peripheral arterial disease? Which are classified as "chronic limb-threatening ischemia (CTLI)," aka "critical limb ischemia (CLI)"?

Answer 33

1. Claudication: Pain with walking 2. Rest pain: Pain in the feet at rest 3. Tissue loss/ulceration/gangrene 2 and 3 are classified as CTLI/CLI

Question 34

Besides aorta, what are other vessels that may develop an aneurysm?

Answer 34

* Popliteal (2nd most common location) * Subclavian * Femoral (99% occur in men) * Hand (usually caused by trauma)

Question 35

What are MMPs?

Answer 35

MMPs = Matrix metalloproteinases * Zinc-dependent enzymes * Secreted as zymogens (proenzymes) * Activated by inflammatory cytokines * **Degrade collagen and elastin**

Question 36

What is a mycotic aneurysm?

Answer 36

An aneurysm due to infection

Question 37

Patient population: 50+ years old, initial clinical presentation of peripheral arterial disease (PAD) What fraction of these patients are are asymptomatic? (Box A)

Answer 37

A: 20-50%

Question 38

Patient population: 50+ years old, initial clinical presentation of peripheral arterial disease (PAD) What fraction of these patients present with typical caudication? (Box C)

Answer 38

10-35%

Question 39

How should type A aortic dissections be treated?

Answer 39

Emergency surgery

Question 40

What defines an abominal aortic aneurysm?

Answer 40

Enlargement of the aortic diameter to 1.5x its normal diameter (Typically \>3cm total for the aorta)

Question 41

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)

Answer 41

B: 30-40%

Question 42

What type of genetic disorders predispose an individual to aortic dissection?

Answer 42

Connective tissue disorders; usually implicated if a young person has an aortic dissection (ex: Marfan's syndrome)

Question 43

What is the most common cause of peripheral arterial disease (PAD)?

Answer 43

Atherosclerosis

Question 44

What is an aortic dissection?

Answer 44

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

Question 45

What causes aneurysms to be pathologic?

Answer 45

If they rupture or thrombose/embolize Rupture usually occurs in body cavities Thrombosis/embolizm usually occurs in extremities

Question 46

List the possible etiologies of abdominal aortic aneurysm

Answer 46

* Atherosclerotic (90%) * Infectious: Mycotic aneurysm * Inflammaotry * Congenital syndromes * Post-stenotic * Pseudoaneurysm * Congenital anatomy