Transcript Diseases of the Thoracic Aorta

Diseases of the Aorta
Seoul National University Hospital
Department of Thoracic & Cardiovascular Surgery
Anatomy of Aorta
 Aortic root
 aortic valve, sinus of Valsalva,
coronary 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
steady 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 Aneurysm
 Definition
 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
biochemical abnormality of extracellular matrix by a mutation in
fibrillin gene on chromosome 15 (Fibrillin-1, 350-KD glycoprotein :
integral structural component of 10-nm noncollagenous microfibrils
of extracellular matrix in most tissue)
2)
The absence of structural integrity of skeletal, ocular, &
cardiovascular system
3)
Adult patients demonstrate abnormal elastic properties
manifested 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
< 5 cm
 6 cm
 8 cm
Risk of rupture within 1yr
4%
43 %
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 enlargement
Symptomatic 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 B
All others without involvement of a-Ao
DeBakey I, II, III
According to the location of intimal tear
Classification of Aortic Dissection
II
A
I
III
B
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
Pain
anterior substernal
Type B
Frequency
posterior, midscapular,
abdominal
Syncope
+++
rare
Dyspnea
+
―
Blood pressure
elevated 50%, low 20%
elevated 80%
Asymmetric pulses
upper, lower extremity
lower extremity
30-50%
Diastolic murmur
50%
10%
Pericardial effusion
+++
rare
Pleural 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
threatening
 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
Diagnostic Studies for DA
 MRI
 Noninvasive study
 Do not require contrast medium
 Better than CT at detecting aortic root
dilatation
 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,
thrombi, atherosclerotic disease
 Intraoperative monitoring
– check cardiac function, aortic valve competency,
atherosclerosis in the thoracic aorta
 Limitation
– requires a skilled cardiologist
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
Surgery of Type A Dissection
 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)
Operation of Type A Dissection
Type A Dissection
Surgery of Acute Type B Dissection
 Techniques
 Similar to the techniques for aneurysm
 Rechanneling blood into the true lumen
 Ligation of all intercostal arteries in acute
dissection
 Surgical indications




Persistent pain
Aneurysmal dilatation ( 5cm)
End organ(kidney, bowel) or limb ischemia
Evidence of retrograde dissection to the a-Ao
Surgical Results of DA
 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 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
(C)
37
Cerebral Metabolic Rate
(% of baseline)
100
Safe Duration of HCA
(min)
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
cerebral perfusion (Frist, 1987)
 Retrograde cerebral perfusion
(Ueda, 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
junction is enlarged
Valve-sparing Operation
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 enlarged, as in anuloaortic ectasia with Marfan syndrome
Valve-sparing Operation
Reconstructing aortic root using a graft with
the aortic valve placed within it
Aortic Root – Wheat Technique
 Separate valve/graft replacement
 For older patients with mild to moderate sinus
dilatation
Aortic Root – Composite Valve Graft
 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 graft & 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
Composite Valve Graft
A; aortic valve is excised
B; composite prosthetic valve conduit is
attached to annulus of aortic valve
Surgery of Aortic Root
 Results
 Early mortality : 2~15%
 Early complications : thromboembolism, bleeding
 Late complications : endocarditis, thromboembolism
pseudoaneurysm
Technique
Major Complications
30-Day Survival (%)
5-Yr Survival (%)
Wheat
Endocarditis (5%)
85
70
Bentall
Thromboembolism (5~10%),
endocarditis (5%)
85~90
70~85
90
85~95
75
70~85
Cabrol
Button
Thromboembolism (2~10%),
endocarditis (5%)
Surgery of Aortic Root
 Results
Ascending Aorta & Arch
 Closed technique
 Limited to a-Ao
 Aorta cross clamp
 Open technique
Arch involvement
Deep 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.)
Surgery of Ascending Aorta & Arch
 Results
Technique
Major Complications
30-Day Survival (30%)
Not reported
25
Not reported
75
Stroke (2~10%)
85~90
+ Antegrade cerebral perfusion
Stroke (5~6%)
80~100
+ Retrograde cerebral perfusion
Stroke (3%)
95
Normothermia
+ Antegrade cerebral perfusion
TCA with profound hypothermia
 Major complications
– stroke, encephalopathy
 Major risk factors
– circulatory arrest time, transverse arch involvement
Descending Thoracic & Thoracoabdominal Aorta
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)
Endovascular Stent Graft
 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%)
Thoracoabdominal Aorta
Modified Crawford’s classification for TAAA
Thoracoabdominal Aorta
– Technique
 Thoracoabdominal incision
 Descending thoracic aorta involvement
Distal aortic perfusion
CSF drainage
Intercostal artery reattachment
(T9~12)
 Celiac axis, SMA, IMA, renal arteries
Visceral perfusion
Carrel patch or bypass graft
Thoracoabdominal Aorta
Descending Thoracic & Thoracoabdominal Aorta
Results
Technique
Major Complications
30-Day Survival
(2~15%),
5-Yr Survival
Descending
thoracic
Neurologic deficit
renal failure (14%)
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%), renal
failure (7%)
90%
60~70%
50~80%
 Risk Factors for poor outcome
– aneurysm extent (type II)
– preop. renal dysfunction
– aortic cross clamp time
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
2
3
4
5
6
Heparin 1mg/kg IV
Mannitol 0.5g/kg in suprarenal clamp
Inferior mesenteric artery occlusion
Lumbar arteries oversewn
Proximal and distal anastomosis
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