Peripheral Vascular Disease Flashcards
What is an aneurysm?
What is an arterial dissection?
Aneurysm:
- Localized dilatation of a blood vessel (aorta) or heart
-
Types:
- True: involves all three layers of wall
- False (pseudoaneurysms): Wall defect leading to extravascular hematoma
Arterial dissection:
- blood enters the wall of the artery
What are the two pathologic processes that can cause an aneurysm?
- Inadequate or abnormal syntheses of collagen
or
- Excessive connective tissue degradation
What syndromes are caused by inadequate or abnormal syntheses of collagen?
What is the pathogenesis for each?
-
Marfan syndrome
- Defective synthesis of fibrillin
- Fibrillin is “scaffolding” for deposition of elastic tissue
- Results in cystic medial necrosis of aorta
- Leads to aneurysm formation & aortic dissection
-
Ehlers-Danlos syndrome
- One variant has defective synthesis of Type III collagen
- Leads to aneurysm formation
How can excessive connective tissue degradation lead to anuerysm formation?
- Occurs with increased matrix metalloproteinase (MMP) or decreased tissue inhibitors of metalloproteinase (TIMP)
- In the setting of inflammation (atherosclerosis) polymorphisms of MMP &/or TIMP genes may predispose to aneurysm formation
What can loss of smooth muscle cells lead to in the vascular wall?
-
Loss of smooth muscle cells
- Thickening of intima (due to atherosclerosis)
- Leads to ischemia of inner media
- Systemic hypertension
- **Narrows vasa vasorum **⇒ ischemia of outer media
- Morphologic results is cystic medial degeneration
What are the most common causes of aneurysms?
- Atherosclerosis – abdominal aorta
- Hypertension – ascending aorta
What are some uncommon causes of aneurysms?
- Congenital defects
- Infections (bacteria, fungi)
- Trauma – AV (fistula) aneurysm
- Vasculitis
- Genetic defects in collagen (Marfan’s & Ehlers-Danlos)
- What congenital defects lead to aneurysm formation?
- What infections lead to aneurysm formation?
-
Congenital defects
- Berry aneurysm: bifurcation of cerebral arteries, subarachnoid hemorrhage
-
Infections (bacteria, fungi)
- Mycotic aneurysm: septic emboli, direct extension, direct infection by circulating organisms
- Syphilis (Treponema pallidum)
- What is the most common location of arotic aneuryms?
- What are some less common locations?
- What is the most common etiology of aortic anuerysms?
- What is the most common association of aortic aneurysms?
-
Abdominal aortic aneurysm (AAA): MOST COMMON LOCATION
- Below renal arteries and above bifurcation
- Less common: Arch of aorta, thoracic aorta and iliac arteries
- Most common cause – atherosclerosis
- More common in men & smokers
Describe the **morphology **of aortic aneurysms:
- Up to 15 cm diameter
- Thinning & destruction of media
- Mural thrombus
- Saccular or fusiform
- Variants:
- inflammatory – unknown etiology
- mycotic – secondary infection (salmonella gastroenteritis) of an atherosclerotic wall
What is the classic clinical presentation of AAA?
What complications can arise from AAA?
- More common in men over 50
- Present as pulsatile abdominal mass
Complications:
- Rupture into peritoneum or retroperitoneum
- Vascular obstruction – renal, mesenteric, spinal arteries
- Embolism of atheroma or mural thrombus to kidneys or lower extremities
- Impingement of ureter(s)
Risk of rupture is directly proportional to ____.
size
- Aggressive management for large aneurysms (> 5 cm)
What are causes of thoracic arotic aneurysms?
- Hypertension
- Marfan’s syndrome
- Syphilis (tertiary)
What are clinical features associated with thoracic aortic aneurysms?
-
Mediastinum encroachment
- Tracheal compression
- Esophageal compression
- Bone erosion
- Cough due to irritation of recurrent laryngeal nerve
-
Cardiac Symptoms
- Heart failure due to aortic valve insufficiency
- Aortic rupture
What causes an aortic dissection?
What is the pathogenesis of aortic dissections?
-
Blood between and along laminar planes of media
- Causes a blood-filled channel that easily ruptures
-
Pathogenesis/etiology
-
Hypertension (40-60 years of age):
- > 90% of cases
- Connective tissue abnormality (younger ages): in association with Marfan’s syndrome or Ehlers-Danlos syndrome
- Ascending aorta most commonly involved
- Rare causes:
- post-procedural – arterial cannulation
- pregnancy
-
Hypertension (40-60 years of age):
What is the morphology of aortic dissection?
What patients have a pre-existing condition to aortic dissection?
- Intimal tear within 10 cm of aortic valve
- Dissection plane between middle and outer thirds of wall, in media
- Usually extends anterograde
- Usually ruptures “out”
- May reenter and form a double-barreled lumen
-
In hypertensive patients
- Vasa vasorum: hyaline arteriolosclerosis
- Media: loss of smooth muscle cells
- Pre-existing pathology of cystic medial degeneration in patients with connective tissue disorder (Marfan syndrome)
What is responsible for aortic dissection in Marfan’s Syndrome?
- Cystic medial necrosis causes connective tissue weakness
- Pools of blue mucinous ground substance disrupt elastic fibers
What is the clinical course of an aortic dissection?
- Dependent on level of aorta involved
- Sharp pain of anterior chest, uneven pulses and widened mediastinum
- Types A and B
-
Classic clinical symptoms:
- Sudden onset of tearing
- Stabbing pain in anterior chest radiating to back
What are complications associated with aortic dissection?
-
Hemopericardium occurs when blood dissects through media, proximally
- causes tamponade
- May also rupture into pleural or peritoneal cavities
What is vasculitis?
What general pathologic processes can cause it?
- Inflammation of vessel walls; may affect any size vessel
- Pathogenesis
- Immune-mediated processes
- Infectious origin
- Unknown
Pathogenesis of Immune-mediated Vasculitis:
Immune-compex mediated
- SLE (Systemic Lupus Erythematosis): DNA – anti-DNA complexes
- Hypersensitivity to drugs
- Viral infections
- HBsAg – anti-HBSsAg
Pathogenesis of Immune-mediated Vasculitis:
Anti Neutrophil Cytoplasmic Antibodies (ANCA) associated
- Autoantibodies against enzymes in granules of neutrophils
- Ab titers mirror clinical severity
-
Two main patterns:
-
Antiproteinase-3 (PR3-ANCA) – Wegener Granulomatosis
- Target antigen: PR3 (neutrophil granule constituent)
- FYI PR3-ANCA = c-ANCA
-
Anti-myeloperoxidase (MPO-ANCA) – Microscopic polyangiitis and Churg-Strauss syndrome
- Target antigen: myeloperoxidase
- FYI MPO-ANCA = p-ANCA
-
Antiproteinase-3 (PR3-ANCA) – Wegener Granulomatosis
What disease is associated with antibodies to endothelial cells?
Kawasaki disease
Vasculitis of infectious origin & unknown origin:
-
Infectious
-
Direct invasion
- Syphilis
- Aspergillus & mucormycosis
-
Indirect
- Immune mechanisms triggering cross-reactivity
-
Direct invasion
-
Unknown
- Giant cell arteritis
- Takayasu arteritis
- Polyarteritis nodosa
- **Large vessel vasculitis: **
- **Medium vessel vasculitis: **
- **Small vessel vasculitis: **
-
Large vessel vasculitis: Granulomatous disease
- Giant cell arteritis
- Takayasu arteritis
-
Medium vessel vasculitis:
- Polyarteritis nodosa - immune complex mediated
- Kawasaki disease - anti-endothelial antibodies
-
Small vessel vasculitis:
- Microscopic polyangitis
- Wegener granulomatosis
- Churg-Strauss syndrome
Giant Cell (Temporal) Arteritis:
- What does it affect?
- What is the etiology?
- What is the clinical presentation, diagnosis and treatment?
- Most common form of systemic vasculitis in adults
-
Affects aorta and its major branches
- temporal artery, ophthalmic, and vertebral arteries
- Pathogenesis: uncertain
-
Clinical:
- > 50 y, often with painful superficial temporal artery, diplopia, visual loss, headache
- Increased ESR
- Diagnosis: biopsy
- Treatment: steroids
What is the **morphology **of temporal (giant cell) arteritis?
- Nodular thickenings of artery with narrowed lumen
- Patchy (discontinuous) segments affected
- Biopsy requires 2-3 cm
- Multiple levels examined
What is the histology of temporal arteritis?
-
Granulomatous inflammation of inner half of media around internal elastic lamina
- Destruction of internal elastic lamina
- Multinucleated giant cells (but not always!)
Describe what is seen in Takayasu Arteritis:
- Pulseless disease (upper extremities), ocular disturbances
- Japanese women younger than 40 yrs
- Granulomatous inflammation of aortic arch and its branches
-
Pulmonary arterties are involved 50%
- coronary and renal arteries may be involved
- Pathogenesis: autoimmune etiology
- Histology: lymphocytes, giant cells, collagenous fibrosis
What is polyarteritis nodosa? What is the pathogensis? How is it treated?
- Systemic segmental transmural necrotizing inflammation of small or medium-sized muscular arteries
- Renal and visceral arteries affected, spares lung
- Focal, random, episodic
- All stages of inflammation and fibrosis co-exist
-
Aneurysms
- Necrosis with karyorrhexis
- Young adults (30% Hep B antigen), no ANCA
- Acute, chronic, subacute, or remittent course
- 90% remission or cure - corticosteroids, cyclophosphamide
What is the classic presentation of polyarteritis nodosa?
- Rapidly accelerating hypertension (renal artery involvement)
- Abdominal pain & bloody stools
- Peripheral neuritis
Kawasaki Syndrome:
- Where is endemic?
- What vessels are affected?
- What is the most common demographic?
- Endemic in Japan
- Rare, but increasing in the US
- Large, medium and small arteries
- often coronaries with aneurysm formation
-
With mucocutaneous lymph node syndrome
- Mucous membrane inflammation
- Enlarged lymph nodes
- 80% are < 4 yrs
- Leading cause of acquired heart disease in children (in Japan)
What does Kawasaki syndrome resemble on histology?
What is the etiology of Kawasaki syndrome?
- Histology: Necrosis and inflammation, aneurysms, resembles polyarteritis nodosa
- Etiology:
- ? autoantibodies to endothelial cells and smooth muscle cells
- ? Infectious agent (virus) trigger
Microscopic Polyangitis
- What vessels are affected?
- What type of ANCA? (if any)
- How will it appear on histology?
-
Arterioles, capillaries, venules
- Skin, mucous membranes, lungs, brain, heart, GIT, kidneys, muscles
- Necrotizing glomerulonephritis (90%) and pulmonary capillaritis
-
MPO-ANCA + in 70%
- Immunologic reaction to antigens- drug, Strep, tumor proteins
- Histology: fibrinoid necrosis, neutrophils, nuclear dust (karyorrhexis)
What determines the major clinical features in microscopic polyangitis?
- Major clinical features are dependent on vascular bed involved:
- hemoptysis
- hematuria
- proteinuria
- abdominal pain or bleeding
- muscle pain or bleeding
- cutaneous purpura
Wegener Granulomatosis
- What areas are affected?
- What type of ANCA? (if any)
-
Necrotizing vasculitis
- Granulomas of lung &/or upper respiratory tract (ear, nose, sinuses, throat)
- Vasculitis of small to medium sized vessels in lungs & upper respiratory tract
- Glomerulonephritis
-
PR3-ANCAs present in >95%
- Likely cell-mediated hypersensitivity response against inhaled infections or environmental antigen
What is the most common demographic affected by Wegener granulomatosis?
What is the prognosis and associated symptoms?
- M > F, ~40 years of age
- Prognosis:
- Without treatment: 1 yr – 80% mortality
- Symptoms:
- Pneumonitis (95%)
- Sinusitis (90%)
- Nasopharyngeal ulcerations (75%)
- Renal disease (80%)
What type of vasculitis is Churg-Strauss syndrome?
allergic granulomatosis and angiitis
Churg-Strauss Syndrome:
- What is it associated with?
- What are the clinical symptoms?
- Is there ANCA association?
-
Small vessel vasculitis associated with
- Asthma
- Allergic rhinitis
- Lung infiltrates
- Peripheral eosinophilia & infiltration of vessels by eosinophils
- Extravascular necrotizing granulomas
-
Clinical symptoms
- Palpable purpura
- GI bleeding
- Renal impairment
- Cardiomyopathy
- Possible hyper-responsiveness to allergic stimulus
- MPO-ANCAs – present in minority
**Thromboangiitis Obliterans (Buerger disease): **
- What areas are affected?
- What are the clinical features?
- Inflammation and thrombosis of medium to small sized muscular arteries and secondarily the veins and nerves
- Tibial and radial arteries
-
Smokers*
- < 35 yrs, Israeli, Indian subcontinent, & Japanese
- Painful ischemic disease
- Gangrene of limbs, requiring amputation
- Etiology unknown
- Direct endothelial cell toxicity by a component of tobacco
What is Raynaud’s phenomena?
What is the difference between primary and secondary?
Paroxysmal pallor or cyanosis of fingers, toes, nose or ears
-
Primary
- Recurrent vasospasm of unknown cause (exaggerated response to cold)
- Young, healthy women
- No structural changes in the arterial walls (until late in disease)
-
Secondary
- Arterial insufficiency due to narrowing
- Can be due to SLE, SS (Systemic sclerosis – Scleroderma), atherosclerosis, Buerger disease