15. Vascular Pathology

What blood vessels do Atherosclerosis affect?

Large and medium arteries

What blood vessels do Arteriosclerosis affect?

Small arteries and arterioles

What blood vessels do Aneurysms affect?

Vary by type of aneurysm

What blood vessels do Vasculitis affect?

• Immune complex vasculitis (SLE): capillaries and venules

• Giant cell arteritis: specific large arteries

What blood vessels do autoregulation affect?

Arterioles and capillary sphincters

What is atherosclerosis?

A systemic vascular disease at bends due to endothelial stress.

What is atherosclerosis associated with?

Dyslipidemia

What does emboli typically include?

• Thromboemboli

• Calcium emboli

• Cholesterol emboi (hollenhorst plaques)

What are the presentations of atherosclerosis?

• BRAO/CRAO: vision loss

• Peripheral vascular disease: gangrene and amputations

• CVA: Ischemic stroke

• Heart: Ischemic heart disease → Dilated cardiomyopathy → CHF; Aortic Valve Disease → Hypertensive heart disease → CHF

• Vascular: Arteriosclerosis

• Abdominal aortic aneurysm

• Renal stenosis

• Death

What is arteriosclerosis?

A systemic vascular disease in small arteries and arterioles. Associated with stress caused by HTN that narrows the lumen of BV by making the BV thick and stiff. No emboli arise from arteriosclerosis.

What are some presentations associated with arteriosclerosis?

• BRVO/CRVO: vision loss

• CVA: hemorrhagic stroke

• Heart: Hypertensive heart disease → CHF

• Vascular issues from arteriosclerosis

• Death

What are the majority of venous occlusions caused by?

90-95% caused by arteriosclerosis; In retina arteries cross over retinal veins at arteriovenous crossings, sharing adventitia. The arterial disease then occludes the vein.

What is another potential cause for venous occlusions?

Hypercoagulopathies at 5%. They do not occur at Arteriovenous crossings.

What is a sign of HTN retinopathy?

Copper wiring

What is the pathogeneis of RVO caused by arterioscleorsis?

1. HTN

2. Arteriosclerosis in retinal artery/arterioles making the artery heavy (hyaline deposition in tunica intima)

3. Compresses underlying vein

4. Vein becomes occluded

5. blood backs up into capillary beds

6. High Pcap causes lysis of capillary beds

7. Hemorrhage → retinal venous occlusion

What are the different shapes of aneurysms?

• Saccular aneurysm

• Fusiform aneurysm

• Dissecting aneurysm

What are the different types of aneurysms?

• Berry aneurysm

• Abdominal Aortic Aneurysms (AAA)

• Dissecting aneurysm/ False aneurysm/ Pseudoaneurysm: Carotid dissections and Thoracic aortic dissection

What differentiates a true aneurysm vs a false aneurysm?

True aneurysms involve all 3 layers of the blood vessel. False aneurysms involve a wall defect (dissection) so that a hematoma forms within the vessel between the intima and media.

What does a fusiform look like?

The entire diameter of the blood vessel is enlarged

What does a saccular or berry aneurysm look like?

A sack-like bulge on one side of the blood vessel

What does a false/pseudo/dissection aneurysm look like?

Separation of the layers

What are Abdominal Aortic Aneurysms?

Fusiform aneurysms in the abdominal cavity that are asymptomatic, but can be life-threatening of it ruptures. The are occasionally found during a physical.

What is the etiology of Abdominal aoritc aneurysms?

Combination of atherosclerosis and HTN

What is the pathogenesis of Abdominal Aortic Aneurysm?

1. Atheroma forms in abdominal aorta, weakening the vessel wall

2. HTN causes dilation, and fusiform aneurysm forms

3. Sequelae:

   1. atheroma ruptures, causing thrombus and/or embolus

   2. Vessel wall can rupture into retroperitoneum with a 90% morality rate

What is the pathogenesis of Dissecting Aneurysm?

Thunic intima breaks and blood can enter between tunica intima and tunica media. The blood separates the vessel layers. Hematoma can form in the dissected layers → source of emboli. Intima can fall into lumen and cause an occlusion → ischemia/infarct.

What are 2 examples of dissecting aneurysms?

Carotid dissection & Thoracic aortic dissection

What is the etiology of a carotid dissection?

Trauma: major and minor

What is the sequelae of a carotid dissection?

• Ischemic Stroke (global or focal)

• BRAO/CRAO

• Horner’s Syndrome (sympathetic affected postganglion neuron)

What part of the aorta does a thoracic aortic dissection affect?

Any part of the thoracic aorta.

What genetic condition can cause both thoracic aortic aneurysm and aortic dissection?

Marfan Syndrome

What can an ascending aortic aneurysm lead to if it tears into the pericardial sac?

• Cardiac tamponade (a life-threatening condition where fluid accumulates in the pericardial sac)

• Death

What happens in a thoracic descending aortic aneurysm?

The aneurysm can tear down the descending aorta (thorax).

What symptoms might survivors of aortic dissection complain of?

A ripping sensation along the roots of the aorta

In an aortic dissection, which layers of the aorta are separated?

The intima and media

What is vasculitis?

A general term for vessel wall inflammation with presentations based on location of inflammation.

What is immune-complex mediated vasculitis

When the patient makes autoantibodies following an infection. It causes petechiae on skin and retina due to capillary hemorrhage. It is a type III hypersensitivity reactions.

What is the pathogenesis of Immune-complex mediated vasculitis?

1. sensitization

2. antibodies produced

3. circulating immune complex forms and deposits on vessel wall

4. activates PMNs and compliment

5. intimal inflammation/damage

6. blood seeps out of vessel, causing petechiae

What is Giant Cell Arteritis (GCA)?

A systemic autoimmune disease affecting temporal, ophthalmic, and vertebral arteries.

What is typically associated with GCA?

• Chronic granulomatous disease (DTH)

• Elevated ESR >60mm/hr

• ELevated CRP

What is the epidemiology of GCA?

• 70+ yrs old

• Most common vasculitis in elderly in US, Canada, and Europe

What arteries can be affected by GCA?

• Temporal artery

• Vertebral artery

• Ophthalmic artery

What are the presentations of the temporal artery being affected by GCA?

• Scalp pain and potential necrosis

• headache

• jaw claudication/hurts to chew

What are the presentations of the vertebral artery being affected by GCA?

Stroke

What are the presentations of the ophthalmic artery being affected by GCA?

• Sudden painful unilateral irreversible vision loss: diffuse vision loss or inferior altitudinal defect; Relative afferent pupillary defect (RAPD)

• Pale, edematous optic nerve; often with flame-shaped hemorrhages

• Can become bilateral vision loss within 24 hours

What is the pathogenesis of GCA?

1. Granulomatous inflammation in the tunica intima and tunica media disrupts the internal elastic membrane

2. Inflammation causes swelling of vessel wall

3. Lumen narrows

4. Vessel can become occluded if the lumen causes pressure to fall below the critical closing pressure

5. Ischemia of downstream tissues

What blood tests should be ordered to determine GCA?

ESR (erythrocyte sedimentation rate) and CRP (C-reactive protein)

Why are ESR and CRP ordered in suspected Giant Cell Arteritis (GCA)?

They are markers of systemic inflammation. Both are typically elevated in GCA and support the diagnosis, but confirmation is via temporal artery biopsy.

What should you do if you suspect the patient has GCA?

Steroids immediately

What is Non-arteritic Anterior Ischemic Optic Neuropathy (NAAION)?

Ischemia of the optic head that is not caused by GCA.

What are the characteristic of NAAION?

• Ischemia to optic nerve head

  • reduced perfusion of superior circle (believed to caused by poor autoregulation)

• Normal ESR and CRP = non-inflammatory

• 2nd most common optic neuropathy after glaucoma

What are the presentations of NAAION?

• Sudden painless unilateral vision loss (somewhat reversible)

  • Inferior altitudinal defect

  • RAPD

• Pale, edematous optic nerve, possible flame-shaped hemorrhages

• Less likely to become bilateral

• Typically noticed in the morning

What are predisposing factors for NAAION?

Having a small crowded disc: nerve fibers packed into small disc are thicker and increases the distance O2 needs to diffuse, thus increases risk of ischemia.

What are factors that cause NAION?

• Nocturnal hypotension with poor autoregulation

• High cholesterol

• Sleep apnea

• Rx:

  • Antihypertensive Rx

  • Erectile dysfunction Rx (within 24 hours)

  • GLP-1?

How can some factors of NAION be prevented?

• Take antihypertensives in the morning to counteract nocturnal hypotension

• Use CPAP for sleep apnea

• Statin for high cholesterol

• Do not take ED meds/lifesyle chagnes if possible

What is the pathogenesis of NAION?

• Dysfunction of autoregulation mechanisms

• poor filling pressures

• Poor venous drainage

What are the differences between arteritic anterior ischemic optic neuropathy (AAION) vs non-arteritic anterior ischemic optic neuropathy (NAAION)

What is Raynaud’s Phenomenon?

Abnormal vasospasm triggered by cold or emotion affecting fingers and toes.

What is raynaud’s phenomenon linked to?

Glaucoma

What does raynaud’s phenomenon cause?

triphasic discoloration “red, white, blue”. Red = vasodilated; white = area vasoconstricted; blue = cyanosis

What can happen if raynaud’s phenomenon is severe?

Gangrene

What is emboli defined as?

Any substance that originates in one vessel and is relocated by blood flow to a new location and is a potential for infarct.

What is Virchow’s triad?

Three main factors that contribute to thrombosis: Stasis of blood flow, endothelial injury, and hypercoagulability.

What substances can become an emboli?

• Atherosclerosis-related

  • thromboemboli

  • hollenhorst

  • calcium

• Air

• Amniotic fluid (during labor and delivery)

• Cancer cells (metastases)

• Venous Thrombosis

• Fat from bone marrow