Aortic Aneurysms & Dissection

Robbins 530 -534

Aneurysm-localized dilation of a blood vessel

• True aneurysm: bounded by generally complete but often atentuated arterial wall

• False aneurysm=extravascular hematoma that communicates with the intravascular space

Types of aneurysms

• Berry Aneurysm-congenital defect in vessel wall

• Mycotic aneurysm-infection that weakens the wall

• Saccular: spherical-5 to 20 cm and partially filled with a thrombus

• Fusiform: gradual, progressive dilation of the complete circumference

Aortic Aneurysms

• Atherosclerotic• Abdominal aorta

• Syphilis • Ascending aorta and root of aortic valve

• Dissecting (not a true aneurysm but better thought of as a dissecting hematoma)• Blood enters wall of aorta

• Hypertension, Marfan’s syndrome

Abdominal Aortic Aneurysm• Atherosclerotic

• Below the renal arteries

• Large thrombus

• Many associated with dense inflammation

• Rupture

• Occlusion of a branch vessel

• Embolism from atheroma

• Impingement of an adjacent structure

Abdominal aneurysm

Abd. Aneurysm with laminated thrombus

Early AAA

Aneurysm repair

AAA repair-- 6 months

Aortic Dissection - Dissecting Hematoma

• Dissection of blood between the media forming a channel within the aortic wall

• Men 40 to 60 years of age with hypertension

• Younger group with Marfan syndrome

Aortic Dissection

• Intimal tear within 10 cm of the aortic valve

• May have another intimal tear where channel reenters the main aortic channel

• Ruptures into pericardial, pleural or peritoneal cavities

• Cystic medial degeneration- break down of elastic fibers

Dissection plane-false lumen

Aortic valveAscending aorta

Dissecting aneurysm

Dissection plane

Dissecting hematoma of aorta lumen

Hematoma-- false lumen

Dissecting aneurysm

True lumen

Dissection- false lumen

Normal aorta

Cystic medial necrosis

Aortic Dissection

• Sudden onset of excruciating pain, anterior chest, radiating to the back and moving downward

• Can be confused with MI

• Transesophageal echo, CT scan

• Surgical repair

Types of dissections

DeBakey Classification

• What determines type?

• Site of the intimal tear, NOT the extent of the false lumen

• Either at the:

• sinotubular junction

• just past L subclav art

Further Imaging: CT vs Aortography

• CT, MRI Aortographyreal size of aneurysm assessment of aorta prox & relation to adj structures distal to aneurysm  

QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Treatment

• Indications for surgical treatmentall symptomatic patientstwice the normal size of the aorta or 7 cm.progressive enlargement 

• Medical managementBeta blockersControl HTN and COPD 

Annulo-Aortic Ectasia• Aneurysmal dilation of sinuses of Valsalva

(Marfan, cystic medial necrosis) 

• Etiology:intrinsic connective tissue defects involve all layersnon-specific medial necrosis in non-Marfan patientsaortic annular dilatation causes aortic regurgitation

• Natural history:Marfan’s (Ehlers-Danlos): < 50% survive > 45 yo

90% CV deaths, 3/4 of these dissection or rupture

Diagnosis • Most are asymptomatic 

• Symptoms/signs of AIbounding pulseswiden pulse pressures

• Marfan syndrome stigmataectopia lentis (87%)arachnodactyly (77%)MV prolapse (90%)

Surgical Rx

•  - signs of AI 

•  - Acute or Chronic Dissection 

•  - Rupture 

•  - progressive enlargement 

•  - Marfan's pt. with size > 5 cm 

Surgical Results: Thoracic Aneurysms & Annulo-aortic Ectasia

• Hospital death      - bleeding, neuro, MI 

•     Ascending Aorta               4-10% 

•     Arch                                   5-50% 

•     Descending                        5-15% 

•     Thoracoabdominal           up to 50%

• postop 5YSR

• Ascending  74% Descending 56%

FALSE LUMEN•   extension related to

velocity of ejection and (dp/dt) 

•  may rupture pericardium, pleura 

•  may occlude branches 

•  may re-enterthru a second tearremains patent, dilates

QuickTime™ and a decompressor

are needed to see this picture.

Treatment - Ascending AortaTypes I, II

• Immediate operation is indicated because rupture likely1-2% mortality per hour during first 48 hrs

• Contraindications:  advanced age, incurable coexisting disease,  paraplegia 

• Note:  new stroke may resolve, not a contraindication

• OPERATIVE STRATEGY: Eliminate INTIMAL TEARReplace ascending aorta, repair or replace aortic valve  Replace arch if false channel leaking or site of tear

Aortic Tear/TransectionAortic Tear/Transection

• 15% of blunt chest trauma deaths

• 90% die at the scene

• 10% (survivors) false aneurysmwithout intervention 50% will die within 48 hrs. 

• 15% of blunt chest trauma deaths

• 90% die at the scene

• 10% (survivors) false aneurysmwithout intervention 50% will die within 48 hrs. 

90% occur at the aortic isthmus

Repair of Aortic Tear/TransectionRepair of Aortic Tear/Transection

• Operation: Graft replacement via left thoracotomy with partial pump bypass (to perfuse spinal cord)  

• Results15-30% mortality7% paralysis15% can be repaired primarily 

• Operation: Graft replacement via left thoracotomy with partial pump bypass (to perfuse spinal cord)  

• Results15-30% mortality7% paralysis15% can be repaired primarily 

Pathology determines treatment

Aneurysm (true)

Dissection Transection

Let’s Summarize• Thoracic Aortic Aneurysm

all layers dilated replace the dilated part

• Annulo-aortic Ectasiaall layers dilated; involves aortic root replace dilated part/ replace or repair aortic valve

• Aortic Dissectiontear in intima; false lumen travels varying distancesreplace part with intimal tear; follow false lumen long-term

• Traumatic Aortic Transectionnear-circumferential disruption of all layers; survive if adventia holdsgraft doesn’t “replace”, it joins the 2 ends together