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