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Aortic Aneurysm

Aortic Aneurysm

1. Morphology

A. Atherosclerotic (degenerative) aneurysm: most common cause (1/2) of localized aortic enlargement
B. Chronic aortic dissection: persistent false channel of outer media and adventitia gradually enlarges
C. Chronic traumatic aortic transection: false aneurysm contained only by aortic adventitia
D. Annulo-aortic ectasia: aneurysmal dilation of sinuses of Valsalva (Marfan, cystic medial necrosis)
E. Aortitis: granulomatous or syphilis

2. Location

Ascending aorta45%
Arch10%
Descending thoracic55%
Thoracoabdominal10%

3. Symptoms

A. Usually asymptomatic
B. Pain implies sudden extension or rupture of aneurysm
1) Ascending aorta - neck, jaw
2) Descending aorta - back, inter-scapular
3) Thoracoabdominal aorta - low back
C. Compression of adjacent structures
1) SVC syndrome
2) Hoarseness, laryngeal nerve

4. Associated Atherosclerotic Disease

Coronary arteries16%
Cerebrovascular10%
Peripheral vascular10%
Abdominal aortic aneurysm10%

5. Diagnosis

A. Chest X-ray - enlarged aortic shadow
B. Aortography - most valuable for assessment of aorta proximal and distal to aneurysm
C. Echocardiography - is useful in the assessment of aortic valve function and can demonstrate an intimal flap.
D. Computed axial tomography - real size of aneurysm and relation to adjacent structures
E. Magnetic resonance imaging - multiple planes possible, cine loop

6. Natural History

A. Aortic aneurysms enlarge, eventually rupture (74%)
B. Large aneurysms(>6 cm) tend to rupture
C. Symptoms herald rupture (2 years)
D. Aneurysm with chronic dissection have worst prognosis

7. Operations - Ascending Aorta and Arch

A. Conventional cardiopulmonary bypass is utilized
B. Aortic valve replacement with valved conduit (Bentall procedure)or repair/resuspension if feasible
C. Arch anastomosis by tailoring or arch vessel reimplantation
D. Reimplant the coronary arteries as buttons
E. Do not cover the graft, as this will increase the risk of false aneurysm
F. Elephant trunk
G. Cerebral perfusion antegrade ? retrograde
H. Deep hypothermia - circulatory arrest

8. Operation - Descending Thoracic Aorta

A. Clamp and go is the traditional method
B. Incise the aneurysm to work inside
C. There are many approaches to protect the spinal cord and kidneys, including:
1) NTP and spinal fluid drainage are somewhat controversial
2) LV or ascending aorta to descending aorta shunt (Gott)
3) LA to femoral artery bypass
4) Femoral-femoral cardiopulmonary bypass
5) Deep hypothermia and circulatory arrest may be the most controlled approach
D. The proximal anastomosis should be precisely matched to the aorta
E. Reattach the intercostal arteries as an island; this is particularly important in the distal portion of the repair
F. The distal anastomosis may be fashioned either end-to-end or as an elephant trunk

9. Operation - Thoracoabdominal Aorta

A. Spinal cord and renal protection are essential
B. Hemorrhage remains a challenging problem
C. Thoracoabdominal incision with a retroperitoneal approach
D. There are also various approaches to these aneurysms:
1) Clamp and go with or without heparinization
2) Deep hypothermia with circulatory arrest
E. Reimplant the visceral and intercostal-lumbar arteries when involved

10. Results

Death (hospital) - bleeding, neuro, MI
Ascending aorta4-10%
Arch5-50%
Descending5-15%
Thoracoabdominalup to 50%
Survival - new aneurysm, CHF, renal
5 years60%
10 years40%