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