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Diseases of the Aorta

Cindy Chan, MD

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Overview

Aortic structure

Dilating disease

Constricting disease Diagnosis

Treatment

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Aortic structure

Aortic layers: intima, media and adventitia

Medial Lamellar units (layers)

Collagen/elastin composition

Most collagen in adventitia (for tensile strength)

Most elastin in media (for compliance)

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Zatina, et al. J Vasc Surg 1:443, 198

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Matrix degradation

Proteases

Matrix Metalloproteinases MMPs

Eg. MMP-1 (collagenase), MMP-2, MMP-9 (elastase)

Protease inhibitors Eg. a-1 antitrypsin

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Dilating disease of the aorta

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Dilating disease of the aorta

Nonspecific Aneurysm

Dissection

Congenital Eg. Marfans Disease, Ehlers-Danlos syndrome

Infection

Trauma

Unusual Eg. Behets Disease

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Nonspecific Aortic Aneurysm

Atherosclerotic - misnomer

Genetic

Males

Inflammation Inflammatory cell infiltrates

Matrix degradation

Increased collagenase and elastase activity

Defective remodeling Cellular and matrix proliferation

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Nonspecific Aortic Aneurysm

Location

Thoracic - rare (Marfans, chronic dissection)

Thoraco-abdominal

Abdominal (most) Natural history

Unpredictable rate of increase

Risk of rupture aneurysm diameter

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Distribution of

aneurysms inaorta

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AAA, Ultrasound Imaging

Aortic Diameter

Mural

Thrombus

Aortic Lumen

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Complications of aneurysms

Rupture

Free, anterior rupture

Retroperitoneal rupture

Rupture into adjacent structures

Inferior vena cava: aorto-cava fistula

Duodenum: aorto-enteric fistula

Thrombosis

Acute arterial occlusion (of the aneurysm itself)

Embolization

Acute arterial occlusion (distally)

Compression of adjacent structures

Veins, nerves, bowel

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Infrarenal AAA

Mortality is 75-90%

5 year rupture risk is related to transverse diameter

< 3 cm ~ 0%

3.5-4.9 cm ~ 5%

> 5.0 cm ~ 25% ( ~20% at 2 years)

> 6.0 cm ~ 40%

> 8.0 cm 75-80%

5.0 cm is cut-off for surgical intervention

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Dilating disease of the aorta

Dissection

Incidence 5-10 / 1,000,000 (~2x rupt AAA) Blood dissects through intima, separating intima from

media

Classification - Stanford A & B

Acute dissection High mortality if untreated

33% 24 h

50% 48 h

66% 1 wk

90% 1 mo

1% mortality rate / hour for the first 48 hours

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Stanford

Classification

Of AorticDissection

Miller, et al., J Thorac Cardiovasc Surg 78:365, 1979.

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Dilating disease of the aorta

Aortic Dissection

Stanford type A ~ 2/3 of aortic dissections

Tear in ascending aorta or arch

Younger, inherited connective tissue disease

High mortality with medical Rx

Stanford type B

~ 1/3 of aortic dissections

Tear in descending aorta

Older patients, chronic hypertension

Equivalent early results with medical Rx

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Effects of aortic dissection on branch arteries

C f

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Rupture of false lumen

Free rupture into chest or abdomen exsanguination

Pericardial tamponade

Compression by false lumen

Aortic annulus aortic insufficiency

Main aortic lumen ischemia

Arterial branches ischemia

Coronary myocardial infarction

Bracheocephalic stroke

Spinal paralysis

Renal renal failure

Mesenteric intestinal infarction

Extremity gangrene Gradual enlargement of false lumen

Chronic dissection false aneurysm Late rupture!

Complications of Aortic Dissection

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From: Hurst and Gore, inDoroghazi and Slater (eds.):

Aortic Dissection, McGraw-

Hill, 1983, p 193.

Aortic segmental

and branch artery

involvement in 450

aortic dissections(by autopsy)

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Dilating disease of the aorta

Focal destruction of arterial wall

Specific pathology

Trauma

Infection Prior vascular repair

Saccular configuration

Less predictable natural history

Expectant management is notappropriate

Also..Pseudoaneurysm

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Aortic Atherosclerotic Ulcers

From: Stanson AW, in Strandness and vanBreda (eds.):Vascular Diseases, Churchill Livingstone, 1994, p 600.

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Perforation of the aorta

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Constricting disease of the aorta

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Constricting disease of the aorta

Congenital

Coarctation

Thoracic

Abdominal (0.5-2% of coarcs)

AcquiredAtherosclerosis

Radiation

Takayasus disease

Tumor

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Constricting disease

Stenosis - limits maximal flow volume throughan artery

Symptoms result from ischemia of organs

Resting demands Increased demands

Exercise

Emotional stress

Digestion

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Constricting disease of the aorta

Atherosclerosis Location

Branch points

Turbulent flow, decreased shear

Abdominal > thoracic aorta

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Arterial adaptation to atherosclerotic plaque

Glagov, et al., N Engl J Med 316:1371, 1987.

Zarins, et al., J Vasc Surg 7:386, 1988.

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Hypoplastic

Aorta

Syndrome

43 yo WF

- Hyperlipidemic- Smoker

- post menopausal

- Rest pain

Calcified aortic (coral reef) atherosclerosis

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Calcified aortic (coral reef) atherosclerosis

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Fibromuscular

dysplasia (FMD) ofthe Iliac artery

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Diagnosis & Treatment ofDilating & Contricting Disease

Diagnosis

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Diagnosis

Symptomatic presentation

Pain Hypotension

Ischemia - visceral, extremity, cerebral

Physical Exam

Pulses / bruits Abdominal masses

Imaging

Lumenal - stenoses: - duplex U/S, arteriography

Mass - aneurysm/ dissection: - CT, MR, U/S

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Treatment

Dilating diseases

Replacement of weakened wall

Control of infection?

Constricting disease Medical therapy for rare cases

Atherosclerosis

Risk factor management

Bypass grafts

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Endoluminal Grafting

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Meadox Vanguard

- nitinol supports

- thin wall seamless fabric

Endoluminal Grafting

Endoluminal Aortic Grafting

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