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Aortic Dissection
高雄長庚醫院心臟內科臨床教授傅懋洋醫師
Aortic Dissection
If untreated• Early mortality(within 48 hours): 1%/hr• 80% mortality within 2 weeks• 90% mortality within 3 months
Operated• In-hospital and follow up mortality:
Proximal type: 21%
Distal type: 29%• Reoperation rate: 7-20%
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Aortic Dissecton
(Am. J. Cardi., 30:263, 1972)Time of survival
Prognosis of untreated acute aortic dissection
Type classifications• Debakey
Type I : begins in AsAo, extends beyond the
AsAo and arch
Type II : begins in AsAo, confined to the AsAo
Type III : originates In the DsAo• Daily
Type A: proximal or ascending
Type B: distal or descending
Aortic Dissection
Aortic DissectionType classifications: Debakey
Aortic DissectionType classifications: Daily Type A Type B
Aortic DissectionType Classifications
Usual sites of primary intimal tear
Segment Number Percent
Ascending 244 61.9
Arch 37 9.4
Isthmus 62 15.7
Descending 41 10.4
Abdominal 10 2.5
Aortic Dissection
Hirst AE et al: Medicine(Baltimore) 37:217, 1958 (505 cases)
Aortic Dissection
Proposed Mechanism of Initiation
• Intimal tear
Aortic blood enter the media
• Medial Hemorrhage
Secondary rupture of the intima
Aortic DissectionProposed Mechanism of Initiation
• Incidence:
5 -10 cases/million/year
2000 new cases/year in USA
AMI / AD : 10-20 / 1
• Sex: M / F : 2 / 1
• Age: Peak : 60 - 70 years old
Proximal type: younger
Aortic Dissection
Aortic DissecionPrediposing Factors in the EtiologyHypertensionCongenital Cardiovascular Diseases Coarctation , Biscuspid aortic valve Aortic hypoplasia, Aortic stenosis Floppay mitral valveInlammatory Conditions Aortitis -- syphilitic, Arteritis -- giant cellTrauma Blunt, IatrogenicCystic Medial Necrosis Marfan syndrome, Ehler-Danlos syndrome Pregnancy
Complications
• Compression of neighboring structures
• Aortic rupture
• Occlusion of branching artery
• Aortic insufficiency
Aortic Dissection
Compression of neighboring structures
Sympathetic ganglia Horner syndrome
Recurrent laryngeal nerve Hoarseness
Trachea or bronchus Airway obstruction
Superior vena cava SVC syndrome
Conduction system AV block
Aortic Dissection
Aortic ruptureExternal Hemorrhage Pericardium Tamponade (most commo
n) Thorax Hemothorax ( Left > Right)
Hemomediastinum Abdomen Hemoperitonium
HemoretroperitoniumInternal Hemorrhage GI tract GI bleeding Trachea Hemoptysis
Aortic Dissection
Aortic Dissection
Mechanism of Arterial Occlusion
Occlusion of branching artery Arteries involved Manifestations
Coronary Myocardial ischemia, infarction
Carotid Stroke, hemiplegia, amaurosis
Innominate and Ischemic upper extremity subclavian
Mesenteric and Intestinal Ischemia, infarction celiac
Renal Hypertension, oligouria, hematuria
Iliac Ischemic lower extremity
Aortic Dissection
Aortic DissectionOcclusion of branching artery
Aortic insufficiency• Dissection may dilate the aortic root, widening the annulus --- --- aortic leaflets unable to coapt • Pressure from dissecting hematoma may depress one leaflet below the line of closure of the others• The annular support of the leaflets or the leaflets themselves may be torn so as to render valve incompetent
Aortic Dissection
Aortic Dissection
Mechanism of Aortic Insufficiency
Diagnosis• History taking• Physical Examination• Chest X-ray• Echocaridography Transthoracic(TTE) Transesophageal(TEE)• Computed Tomography(CT)• Magnetic Resonance Image(MRI)• Aortography
Aortic Dissection
Acute Aortic DissectionClinical Features• Severe pain in chest, Intrascapular region, back• Syncope• Amaurosis• Dyspnea• Nausea, or vomiting• Abdominal pain• Melena, or hematemesis• Oligouria, anuria, or hematuria• Paralysis, weakness, and numbness
Pain• 90% of presentations• Cataclysmic in onset• earing? ?ripping? tabbing• Migratory(70%)• Associated with vasovagal symptoms:
Drenching sweating, apprehension,
Nausea, vomiting, faintness• Locations
Aortic Dissection
Physical Findings• Hypertension• Shocky appearance, hypotension• Deficiency of pulses• Unilateral or bilateral jugular venous engorgement• Pleural effusion ( Hemothorax )• Rales, congestive heart failure• Aortic regurgitation• Cardiomegaly• Cardiac tamponade• Absent bowel sound• Bruit• Hemiparaplegia, anesthesia, paresthesia, paraparesis
Acute Aortic Dissection
Blood PressureHypertension (90%)
Ususally elevated at admission
Hypotension(systoic < 100mmHg)
usually indicates complication
Paradoxical pulse
Pseudo-hypotension
Unequal in arms - occlusion of innominate or
left subclavian artery
Wide pulse pressure in AR
Aortic Dissection
Neck veinUnilateral engorgement Compession of jugular veinBilateral engorgement Comression of SVC Pericardial effusion Cardiac tamponade Congestive heart failureFlat or low CVP Indicate complications Rupture
Aortic Dissection
Chest plain film• Normal• Abnormal mediastinum• Abnormal aorta
a. Disparity in size
b. Double aortic shadow
c. Irregular contour
d. Displaced intimal calcification• Abnormal cardiac silhouette• Displacement of trachea, esophagus
Aortic Dissection
Aortic Dissection
Imaging Technologies
• Aortography
• Computerized tomography
• Magnetic resonance imaging(MRI)
• Echocardiography
Transthoracic
Transesophageal
Angiographic Findings1. Direct signs
a. Intimal flap
b. Double lumens
2. Indirect signs
a. Compressed true lumen
b. Thickened aortic wall
c. Ulcer like projection
d. Abnorml catheter position
e. Aortic insufficiency
f. Branch abnormality
Aortic Dissection
CT Findings1. Detection of intimal flap2. Identification of two lumina a. Differential density between two lumina in precontrast images b. Compression deformity of the true lumens by the false lumen c. Delayed flow rate in false lumen by dynamic scanning3. Displaced intimal calcifications from outer aortic contou
r4.Aortic lumen widening a. Disparate sizes of AsAo and DsAo5. Associated complications
Aortic Dissection
Echocardiography(I)• Transthoracic
Type A (+)
Type B ?• Transesophageal
Type A (+)
Type B (+)
High diagnostic accuracy
Aortic Dissection
Echocardiography(II)• Recognition of intimal flap
• Aortic root dilatation
• Widening aortic root walls
• Aortic regurgitation
• Pericardial effusion
• Cardiac tamponade
• Pleural effusion
Aortic Dissection
Aortic Dissection
Accuracy of diagnostic modality
Sensitivity Specificity
Aortography 88% 94%
CT scanning 82-100% 90-100%
MRI 100% 100%
TTE 59-85% 63-96%
TEE 99% 97%
Aortic DissectionPrinciples of modality for diagnosis• Confirmation of dissection
• Determination of whether or not the ascending aorta is involved
• Detection of entry sites
• Demonstration of abnormal anatomic features
• Detection of complications
• Risk of the examinations
• Sensitivity, specificity, and predictive accuracy
• Time for diagnosis
• Cost-benefit advantage
Aortic DissectionComparison of different imaging modalities
Aortogram CT scan MRI TEE
Confirmation +++ ++ +++ +++
Tear site ++ + ++++ +++
Complication ++ + +++ ++++
Contrast +++ ++ - -
Convenience + ++ + +++
Cost ++++ ++ +++ +
Risk ++++ + + +
Follow up + ++ +++ ++++
Differential Diagnosis• Myocardial infarction• Acute aortic regurgitation• Coronary insufficiency• Thoracic aneurysm• Mediastinal tumors• Pericarditis• Musculoskeletal pain
Aortic Dissection
Pain
Aortic dissection Myocardial infarction
Prodrome - +
Onset Abrupt Gradual
Maxium at outset Delayd
Persistence + +
Radiation neck, back, legs neck, arms
Migration + -
Aortic Dissection
Aortic dissection Myocardial infarction
BP usually elevated normal or low Pulse defict + -AR murmur + -Neurological + - manifestationEKG infarction - +Chest X-ray Mediastinal widening + - Calcium sign + - Double lumen + -
Aortic Dissection
Management• Relief of chest pain• Monitor of blood pressure(on arterial line)• Control hypertension
Vasodilator is avoid• Place the patient in intensive care unit• Consult CVS surgeon• Initiate the diagnostic procedure• Type A aortic dissection -- operation• Type B aortic dissection -- medical treatment• Complicated aortic dissection -- operation
Aortic Dissection
Indications for treatment• Surgical 1. Treatment of choice for acute proximal type 2. Acute distal type complicated with a. Progression with vital organ compromise b. Rupture or impending rupture c. Aortic regurgitation(rare) d. Retrograde extension into ascending aorta e. Dissection in Marfan syndrome
• Medical 1. Treatment of choice for uncomplicated distal type 2. Treatment for stable, isolated arch dissection 3. Treatment of choice for stable chronic dissection (2 weeks or later after onset without complications)
Aortic Dissection
Indications for definitive surgical therapy1. Type A aortic dissection
2. Aortic valve insufficiency, secondary to dissection
3. Impending rupture
4. Progression of the dissection hematoma
5. Compromise or occlusion of a major branch of the Ao
6. Acute saccular aneurysm
7. Blood in pleural space or pericardium , or both
8. Inability to relieve and control pain
9. Inability to bring blood pressure and cardiac
pulse under control within 4 hours
10. Marfan syndrome or annuloaortic ectasia
Aortic Dissection
Indications for intensive drug therapy1. Drug therapy is the initial treatment of choice in all patients with acute aortic dissection2. Type B aortic dissection without involvement of AsAo3. The site of intimal tear cannot be identified without involvement of AsAo4. The site of origin of acute dissetion is in transverse arch without extension into AsAo5. Patients who are poor surgical risks in general6. Failure of opacification of the false channel
Aortic Dissection
Goals for medical therapy• Reduction of the blood pressure
< 100 - 120 mmHg in systole
lowest level tolerated with
adequate vital organ perfusion
• Decrease the velocity of ventricular
contraction ( dp/dt )
Aortic Dissection
Drugs used in control of hypertension• Trimethaphan (Arfonad)• Sodium nitroprusside (Nipride)• Betablockers• Alpha + betablocker ( Labetalol)• Methyldopa• Clonidine• Reserpine• Guanethidine( Ismelin)• Diuretics
Aortic Dissection
Aortic DissectionCritical determinants of prognosis• Age• Site of intimal tear• Presence of complications:
Pericardial effusion
Aortic regurgitation• Formation of thrombus in false lumen• Prompt and accurate diagnosis and managem
ent
Prognosis
Proximal Distal
Acute Chronic Acute Chronic
Hospital Surgical 53% * 92% 51% 83%
survival *
Medical 56% 80% 100%
Late Surgical 82% 70% 82% 60%
survival
Medical 80% 64% # 100%
* P<0.01, # P<0.05 (MGH 1963-1978)
Aortic Dissection
Mortality
Proximal Distal
Medical(136) 69% 20%
Surgical(188) 35% 49%
Aortic Dissection
Aortic Dissection
Poor prognostic factors• Presence of an open false lumen with persistent communi
cation between true lumen• Extravasation of fluid in the pleural cavity or the mediast
inum
Good prognostic factors• Thrombus formation in the false lumen
Raimund Erbel, et al: Circulation 1993;87:1604-1615