Upload
gloria-king
View
235
Download
0
Tags:
Embed Size (px)
Citation preview
Diseases of the AortaDiseases of the Aorta
Seoul National University HospitalDepartment of Thoracic & Cardiovascular Surgery
Anatomy of Aorta
Aortic root aortic valve, sinus of Valsalva, c
oronary artery Ascending aorta
aortic root ~ innominate artery Aortic arch
proximal, distal Descending thoracic aorta
distal to LSCA ~ 12th ICS Thoracoabdominal aorta
descending thoracic aorta & abdominal aorta
Properties of Aorta & Major Conduit
1. Aorta
Compliant vessel (Windkessel function)
; transforms pulsatile hydraulic energy into a more ste
ady flow by elastic distension & contraction
2. Synthetic conduit
Noncompliant
; must result in alteration of arterial hemodynamics
& LV load (increased impedance & afterload)
Diseases of Thoracic Aorta
Aortic aneurysm
Aortic dissection
Obstructive disease of branches
of the thoracic aorta
Traumatic aortic rupture
Pathophysiology of Aortic AneurysmDefinition
localized or diffuse dilatation > 50% of normal diam. Most common aortic disease that require surgery
Etiology Atherosclerosis ( + underlying weakness) Chronic aortic dissection Annuloaortic ectasia (Marfan syndrome) Trauma Infection Associated with aortic valve disease
Histopathology of Ascending Aortic Aneurysm
1. Cystic medial necrosis by pooling of mucoid material
2. Elastin fragmentation by disruption of elastin lamellae
3. Fibrosis as an increase in collagen at the expense of smooth muscle cells
4. Medionecrosis as areas with apparent loss of nuclei
Pathophysiology of Ascending AA
Marfan syndrome Incidence
– 1 / 5,000 Annuloaortic ectasia is very common Associated defects
– Aortic regurgitation, mitral valve prolapse, dysrhythmia
– Tall stature, long limbs and digits, anterior chest deformity, joint laxity, vertebral column deformity
– High arched palate, lens disorder
Marfan’s Syndrome
* Definition
1) A heritable disorder (AD) of connective tissue involving biochemic
al abnormality of extracellular matrix by a mutation in fibrillin gene on
chromosome 15 (Fibrillin-1, 350-KD glycoprotein : integral structural c
omponent of 10-nm noncollagenous microfibrils of extracellular matr
ix in most tissue)
2) The absence of structural integrity of skeletal, ocular, & cardiov
ascular system
3) Adult patients demonstrate abnormal elastic properties manifes
ted by decreased aortic distensibility & increased stiffness index
Marfan’s Syndrome
Clinical manifestations Cardiovascular
Ocular
Skeletal abnormality
Cardiovascular manifestations Progress with time Mitral valve prolapse in 100% Aortic root dilatation in 80% Rarely atrial septal aneurysm
Manifestations of Marfan’s Syndrome
1. Patterns of aortic dilatation 1) 80% of the patients shows aortic dilation
2) more commonly generalized form than localized form
3) more commonly aortic regurgitation in generalized form
2. Natural prognosis 1) Life expectancy is significantly reduced (40~50) as a
consequence of aortic dilatation & its complications
(aortic dissection, fatal rupture, AR, heart failure)
Marfan’s Syndrome in Children
1. Diagnosis can be made at any age with marked variation
in clinical expression.
2. Patients without family history (in one third of patients
of all age) have more severe manifestation probably
due to sporadic mutation.
3. Surgery should be carried out even in asymptomatic
patients, once the diameter of the aortic root or
ascending aorta reaches 5 to 6cm as in adults.
4. Mitral valve prolapse is as common as aortic root
dilatation and progression can cause significant
morbidity & mortality.
Patterns of Aortic Aneurysm
Locations of Aneurysm
Ascending aorta 45 %
Aortic arch 10 %
Descending thoracic aorta 35 %
Thoracoabdominal aorta 10 %
Natural History of AA
Aortic aneurysm Incidence
– 5.9 new aneurysms / 100,000 person-years Life time probability of rupture : 75~80% 5-yr untreated survival rate : 10~20% Median time to rupture : 2~3 yrs
Size Risk of rupture within 1yr
< 5 cm 4 % 6 cm 43 % 8 cm 80 %
Clinical Presentation of AA Symptoms & signs
Asymptomatic Compressive symptoms
– recurrent laryngeal n. or vagus n. : hoarseness– tracheobronchial tree : dyspnea– pulmonary a. : fistula, bleeding pulmonary HT & edema– esophagus : dysphagia– stomach : sensation of satiety wt. loss
Pain aneurysmal expansion
Intestinal angina, renovascular HT associated atherosclerotic obstructive disease (5% in TAAA)
Physical finding - usually unremarkable Wide pulse pressure, diastolic murmur AR
Indications for Aortic Aneurysm
Aneurysm diameter 5cm Aneurysm with documented enlargementSymptomatic aneurysm
― chest pain or back pain indicating expansion
― significant aortic regurgitation
Dissecting Aortic Aneurysm
Catastrophic event Intimal tear False channel
in the outer half of the media
highly susceptible to rupture
Acute dissection < 2 wks from Sx onset
Chronic dissection > 2 wks from Sx onset
Pathophysiology of Aortic Dissection
Malperfusion Reentry
Predisposing Factors of DA
Hypertension Cystic medial necrosis Marfan syndrome AAE(annuloaortic ectasia) Bicuspid aortic valve Coarctation Pregnancy Chest trauma
Classification of Dissection
Standford Type A
Involvement of the a-Ao ( arch or d-Ao) regardless of site of primary intimal tear
Type BAll others without involvement of a-Ao
DeBakey I, II, IIIAccording to the location of intimal tear
Classification of Aortic Dissection
A B
II I III
Natural History of DA
Annual incidence 5~10 / million
Sex ratio M:F = 2:1 ~ 5:1
Acute dissection Median time to rupture : 3 days Mortality rate ; 50 % within 2 days
75 % within 2 wks
Chronic dissection Median time to rupture : 1~3 Yrs Follows patterns of non-dissecting aneurysm
Clinical Presentation of DA
Acute dissection Excruciating pain
– abrupt onset– sudden rise to peak – Chest pain
2/3 of a-Ao dissection
– Back pain dissection distal to aortic arch
– Pain may migrate as the dissection moves distally.
Various extent of peripheral & central vessel occlusion– from progression of dissection through the false lumen
Failure of diagnosis : major problem
Clinical Presentation of DA
Type A Type B Frequency
Pain anterior substernal posterior, midscapular, abdominal
Syncope +++ rareDyspnea + ―Blood pressure elevated 50%, low 20% elevated 80%Asymmetric pulses upper, lower extremity lower extremity 30-50%Diastolic murmur 50% 10%Pericardial effusion +++ rarePleural effusion ± +++Hemiparesis or plegia + ― 5-6%Paraparesis or plegia + + 2-6%Renal, intestinal infarction + + 3-5%Myocardial infarction + rare 10 %
Principle of Treatment in DA
Type A acute aortic dissection Emergent operation
Type B acute aortic dissection Medical Tx and observation unless life threateni
ng Surgical indication
– Persistent pain– Aneurysmal dilatation ( 5cm)– End organ (kidney, bowel) or limb ischemia– Evidence of retrograde dissection to the a-Ao
Medical Management of DA Initial management
Immediate ICU care
BP control & Monitoring
– Central line, arterial line, urine output
Imaging studies
– Daily Chest X-ray, weekly CT scan during hospitalization
Pharmacologic therapy Vasodilator : Sodium nitroprusside
β-blocker : Esmolol (β-1 selective & short acting)
Diagnostic Studies for DA
CT & CT angiography Aneurysm size, location, extent, intimal tear site
Other pathologies in the chest & abdomen
Follow-up study : aneurysm growth
Limitation – unreliable detection of root enlargement
Contraindication – renal insufficiency, allergy to contrast agents
MRI Noninvasive study Do not require contrast medium Better than CT at detecting aortic root dila
tation Disadvantages
cost required time (esp, in acute dissection)
Contraindication pacemaker, claustrophobia
Diagnostic Studies for DA
Transesophageal Echocardiography (TEE) Accuracy in imaging intimal tear : 90%
Assessment of cardiac structure & function
Highly sensitive in aortic pathology diagnosis – aortic valve disease, aortic dilatation, dissection, thromb
i, atherosclerotic disease
Intraoperative monitoring– check cardiac function, aortic valve competency, atheroscl
erosis in the thoracic aorta Limitation
– requires a skilled cardiologist
Diagnostic Studies for DA
Diagnostic Studies for DA Aortography
Geography of the aorta & condition of smaller vessels Previous gold standard in dissection
– double lumen, tear site, extent Indication
– renovascular HT, intermittent claudication, atherosclerotic occlusive abdominal aorta, symptoms of carotid artery occlusion
Disadvantages– invasive procedure using radiopaque dyes
Cardiac cath & coronary angiography Evaluation of the concomitant coronary artery disease
Principles of Surgical Tx in Acute Dissection Resection of aortic segment containing intimal tear
Obliteration of false lumen in both end of remained aorta Graft replacement of resected aortic segment
Techniques Median sternotomy Femoral-femoral bypass Trendelenburg position Circulatory arrest with deep hypothermia Retrograde cerebral perfusion Reinforcement of the intima & adventitia together
(sandwich technique)
Surgery of Type A Dissection
Operation of Type A Dissection
Type A Dissection
Techniques Similar to the techniques for aneurysm Rechanneling blood into the true lumen Ligation of all intercostal arteries in acute dissecti
on
Surgical indications Persistent pain Aneurysmal dilatation ( 5cm) End organ(kidney, bowel) or limb ischemia Evidence of retrograde dissection to the a-Ao
Surgery of Acute Type B Dissection
Acute Type A Dissection Early mortality : 20~30 % Main cause of death underlying end-organ injury Major complications stroke (9%) Major risk factors for postop. stroke
– pump time, episode of severe hypotension
Acute Type B Dissection Early mortality : 25~50 % (cf. medical treatment : 7~32 %) Major complications : ischemic spinal cord injury
Surgical Results of DA
Surgical Treatment of AA Aneurysm : Aortic Root, a-Ao, Aortic Arch
Historical evolution
1950s : Cardiopulmonary Bypass (Gibbon)
1955 : 1st successful a-Ao repair (Cooley & DeBakey)
1964 : 1st successful replacement of entire a-Ao (Wheat)
– CPB, coronary perfusion, myocardial cooling, cold cardiac arrest
1968 : Composite valve graft (Bentall & de Bono)
1975 : Replacement of entire aortic arch (Griepp)
– profound hypothermia & circulatory arrest
Aortic Root, Ascending Aorta, Aortic Arch
Limitation of profound hypothermia< 30 min : safe duration > 45 min : increased incidence of stroke> 65 min : increased incidence of death
Calculated safe duration of hypothermic circulatory arrest Temperature Cerebral Metabolic Rate Safe Duration of HCA
(C) (% of baseline) (min)
37 100 5
30 56 ( 52 ~ 60 ) 9 ( 8 ~ 10 )
25 37 ( 33 ~ 42 ) 14 ( 12 ~ 15 )
20 24 ( 21 ~ 29 ) 21 ( 17 ~ 24 )
15 16 ( 13 ~ 20 ) 31 ( 25 ~ 38 )
10 11 ( 8 ~ 14 ) 45 ( 36 ~ 62 )
Aortic Root, Ascending Aorta, Aortic Arch
Adjuncts for brain protection
Reintroduction of antegrade cere
bral perfusion (Frist, 1987)
Retrograde cerebral perfusion (U
eda, 1989)
Aortic Root - Techniques
Median sternotomy Antegrade and/or retrograde cardioplegic perfusion Techniques for aortic root
– Wheat – Composite graft (esp, for Marfan)
Bentall Cabrol modified Cabrol button
– Homograft– Valve sparing procedure Choice of tube graft ; diameter of 10%
smaller than the length of the free
margin of the aortic leaflet
Valve-sparing Operation
Resorting aortic root dimensions in an aortic valve-sparing operation when aortic annulus is normal and sinotubular junctio
n is enlarged
Resorting aortic root dimensions in an aortic valve-sparing operation when aortic annulus is normal and sinotubular junctio
n is enlarged
Valve-sparing Operation
Resorting aortic root dimensions when aortic annulus & sinotubular junction are normal, as in aortic dissection
Resorting aortic root dimensions when aortic annulus & sinotubular junction are normal, as in aortic dissection
Valve-sparing Operation
Resorting aortic root dimensions when aortic annulus and sinotubular junction are enla
rged, as in anuloaortic ectasia with Marfan syndrome
Resorting aortic root dimensions when aortic annulus and sinotubular junction are enla
rged, as in anuloaortic ectasia with Marfan syndrome
Valve-sparing Operation
Reconstructing aortic root using a graft with the aortic valve placed within it
Reconstructing aortic root using a graft with the aortic valve placed within it
Separate valve/graft replacement For older patients with mild to moderate sinus
dilatation
Aortic Root – Wheat Technique
Bentall technique Coronary artery reattachment
side-to-side anastomosis Disadvantage
bleeding d/t anastomosis tension → pseudoaneurysm (7~25%)
Aortic Root – Composite Valve Graft
Cabrol technique Coronary artery reattachment
– a small graft to the both coronary arteries
– side-to-side anastomosis of the small graft & composite graft
Advantage– ↓anastomosis tension
Disadvantage– kinking at the anastomosis sites
Aortic Root – Composite Valve Graft
Modified Cabrol technique Coronary artery reattachment
– a small graft to the LCA– end-to-side anastomosis of the small gra
ft & composite graft– button attachment of the RCA
Advantage– ↓kinking
Aortic Root – Composite Valve Graft
Button technique Coronary artery reattachment Carrel patch for both coronary a.
Direct anastomosis to the composite graft
Aortic Root – Composite valve graft
Composite Valve Graft
A; aortic valve is excised
B; composite prosthetic valve conduit is
attached to annulus of aortic valve
A; aortic valve is excised
B; composite prosthetic valve conduit is
attached to annulus of aortic valve
Results Early mortality : 2~15% Early complications : thromboembolism, bleeding Late complications : endocarditis, thromboembolism
pseudoaneurysmTechnique Major Complications 30-Day Survival (%) 5-Yr Survival (%)
Wheat Endocarditis (5%) 85 70
Bentall Thromboembolism (5~10%), endocarditis (5%)
85~90 70~85
Cabrol 90 75
Button Thromboembolism (2~10%), endocarditis (5%)
85~95 70~85
Surgery of Aortic Root
Surgery of Aortic Root Results
Closed technique Limited to a-Ao Aorta cross clamp
Ascending Aorta & Arch
Open techniqueArch involvementDeep hypothermia & circulatory arrest
–EEG monitoring–Retrograde cerebral perfusion
Elephant Trunk Technique (by Borst, 1988) for extensive aortic aneurysm
(“mega-aorta”)
Elephant Trunk Technique (Staged op.)
Results
Major complications – stroke, encephalopathy
Major risk factors – circulatory arrest time, transverse arch involvement
Technique Major Complications 30-Day Survival (30%)
Normothermia Not reported 25
+ Antegrade cerebral perfusion Not reported 75
TCA with profound hypothermia Stroke (2~10%) 85~90
+ Antegrade cerebral perfusion Stroke (5~6%) 80~100
+ Retrograde cerebral perfusion Stroke (3%) 95
Surgery of Ascending Aorta & Arch
Spinal protection Arterial radicularis magna (Adamkiewicz a.) Technique
– Shunt– Hypothermic circulatory arrest– Spinal cord cooling – Pharmacologic agent – Sequential aortic clamp– Distal aortic perfusion– CSF drainage– Intercostal artery reattachment (T9~12)
Descending Thoracic & Thoracoabdominal Aorta
Indications – Poor surgical candidates for
thoracic aneurysm – Expected survival time < 5 yrs
Problem – Endoleaks (→ graft migration)– Exclusion of intercostal arteries– Lack of long-term data
Results– Early mortality : 9%– Complications
stroke (7%) paraplegia (3%) early endoleak (24%) reintervention (5%)
Endovascular Stent Graft
Modified Crawford’s classification for TAAA
Thoracoabdominal Aorta
–Technique Thoracoabdominal incision Descending thoracic aorta involvement
Distal aortic perfusionCSF drainageIntercostal artery reattachment
(T9~12) Celiac axis, SMA, IMA, renal arteries
Visceral perfusionCarrel patch or bypass graft
Thoracoabdominal Aorta
Thoracoabdominal Aorta
Descending Thoracic & Thoracoabdominal Aorta Results
Risk Factors for poor outcome– aneurysm extent (type II)– preop. renal dysfunction– aortic cross clamp time
Technique Major Complications 30-Day Survival 5-Yr Survival
Descendingthoracic
Neurologic deficit (2~15%),renal failure (14%)
50~80%
TAAA type I, II& IV
Neurologic deficit (0~15%),renal failure (5~25%)
90~95 % 60~75%
TAAA type II,no adjuncts
Neurologic deficit (30~40%),renal failure (17%)
78% 35%
TAAA type II,with adjuncts
Neurologic deficit (12%), renalfailure (7%)
90% 60~70%
Abdominal Aortic Aneurysm
1. Type Fusiform : most
Sacciform
Dissecting : rare
False
2. Etiology Atherosclerosis : 90%
Traumatic
Syphilitic
Congenital
Infected
Pregnancy related
Anastomotic
Pathophysiology of Abdominal Aorta
Nature of the aortic wall
1) Contain more elastin, deposition of
cholesterol and calcium
2) Stress factor and turbulent flow due to
origin of major branches
3) Stability of proximal abdominal aorta and
presence of large bifurcation
Hemodynamic factor
Physical factor
Procedures for Abdominal AA
1 Heparin 1mg/kg IV
2 Mannitol 0.5g/kg in suprarenal clamp
3 Inferior mesenteric artery occlusion
4 Lumbar arteries oversewn
5 Proximal and distal anastomosis
6 Reimplantation of inferior mesenteric
artery
Operative Complications
1 Division of parasympathetic and
sympathetic nerves crossing the
proximal common iliac arteries
2 Peripheral embolism
3 Paralytic ileus
4 Aortoenteric fistula