1. Coarctation of Aorta Seoul National University Hospital
Department of Thoracic & Cardiovascular Surgery

2. Coarctation of Aorta 1. Definition 2. History
A congenital narrowing of upper descending thoracic aorta
adjacent to the site of attachment of ductus arteriosus
2. History
Morgagni : 1st description in 1760
Bonnett : postductal & preductal type in 1903
Crafoord : 1st coarctation repair in 1944
Vorsschulte : prosthetic onlay graft or vertical incision
and transverse closure in 1957
Waldhausen : subclavian patch aortoplasty in 1966

3. Coarctation of Aorta Developmental factor
1. Underdevelopment or hypoplasia of aortic
arch or isthmus
Definition of hypoplasia
* Proximal arch : 60% of ascending aorta
* Distal arch : 50% of ascending aorta
* Isthmus : 40% of ascending aorta
2. Presence of ectopic ductal tissue in the aorta

4. Aortic Arch Hypoplasia
Definition
Hypoplastic arch has higher ratio of elastin lamellae to vessel diameter & increase in collagen and decrease in alpha-actin-positive cell that may hinder the ability of arch to distend.
1. 50% reduction of terminal end of ascending aorta, sometimes,
because of small ascending aorta in coarctation, descending
thoracic aorta is compared.
2. Transverse arch diameter less than body weight in Kg plus 1
3. Z-value less than –2 or more

5. Coarctation of Aorta Morphology 1. Localized stenosis
* More than 50% reduction in cross sectional area
* Shelf, projection, infolding of aortic media into the
lumen opposite the ductus arteriosus
* Usually intimal hypertrophy ( intimal veil ) extends
the shelf circumferentially and further narrows the
lumen (Rodbard)
2. Tubular hypoplasia
* Severe with lesser narrowing
* Proximal aortic & arterial wall
* Distal aortic arch narrowing
* Fetal flow pattern (Rudolph)

6. Coarctation of Aorta
Evolution

7. Coarctation of Aorta Pathophysiology
Narrowed aorta produces increased left ventricular afterload and wall stress, left ventricular hypertrophy, and congestive heart failure.
Systemic perfusion is dependent on the ductal flow and collateralization in severe coarctation

8. Coarctation of Aorta Associated pathology 1. Collateral circulation
* Inflow : primary from branches of both subclavian arteries
. internal mammary artery vertebral artery
. costocervical trunk thyrocervical trunk
* Outflow : into descending aorta, two pairs of intercostal arteries
2. Aneurysm formation of intercostal arteries
* 3rd, & 4th rib notching * rare before 10 years of age
3. Coronary artery dilatation and tortuosity
* due to LVH
4. Aortic valve
* bicuspid (27-45%) * stenosis ( 6 - 7%)
5. Intracranial aneurysm
* berry type intracranial aneurysm in some patients
6. Associated cardiac anomaly
* 85% of neonates presenting COA

9. CoA Localized

10. CoA Tubular Hypoplasia
Distal arch
PDA

11. Coarctation of Aorta Natural history 1. Incidence
* 5-8% of CHD (5 per live births)
* Isolated CoA (82% of total CoA) ; male:female = 2:1
CoA + VSD 11%, COA + other cardiac anomalies 7%
* Complex CoA ; no sex difference
2. Survival of pure CoA
* 15% : CHF in neonate or infancy
* 85% : survive late childhood without operation
* 65% : survive 3rd decade of life (2% at 60 years)
3. Bacterial endocarditis : common in 1st 5 decades
4. Aortic rupture : 2~3rd decade
5. Intracranial lesion : subarachnoid hemorrhage(cong. Berry
aneurysm)

12. Collaterals in CoA

13. Coarctation of Aorta Clinical features & diagnosis 1. Infancy
1) Closure of ductus (7-10 days) produces severe obstruction
2) Ductus arteriosus remains patent - differential cyanosis
3) Associated intracardiac defect - more severe, early onset
4) Degree of collateral circulation
2. Childhood
* Asymptomatic without significant associated lesion
* Hypertension (90%) * Cardiomegaly (33%)
* Rib notching (15%)
3. Adolescence and adult
* Hypertension ; very common * Valvar heart disease
* Heart failure at 30 years of age
4. Associated syndrome
* Turner syndrome (XO) : 2% * Von Recklinghausen’s D
* Noonan’s syndrome or congenital rubella

14. Coarctation of Aorta Indications for operation
1. Reduction of luminal diameter greater
than 50% at any age
2. Upper body hypertension over 150mmHg
in young infant ( not in heart failure )
3. CoA with congestive heart failure
at any age

15. Coarctation of Aorta Techniques of operation
1. Subclavian flap aortoplasty
Neonate, infant and child up to 10 years
2. End-to-end anastomosis
Preferred in any age group
* Extended end-to-end anastomosis
* Radically extended end-to-end anastomosis
3. Patch angioplasty or graft replacement

16. Prevention of Recoarctation
Ideal operative procedure
Successfully address transverse arch hypoplasia (if present),
Resection of all ductal tissue, and
Prevention of residual circumferential scarring at the aortic anastomotic sit.
Factors
Younger age at operation
Presence of aortic arch hypoplasia remain risk factors for recoarctation

17. Regional Cerebral Perfusion
Technique
We begin full-flow CPB at a calculated baseline of 150 mL · kg–1 · min–1 and, after snare placement on the proximal brachiocephalic vessels, initiate RLFP by reducing pump flow to 50% of baseline.
We make further adjustments such that baseline cerebral blood flow velocity as measured by transcranial Doppler and cerebral oximetrics as measured by NIRS are optimally maintained.
RLFP provides consistent cerebral circulatory support and that this support is bilateral, despite being applied to the inominate artery.

18. Pediatric Cardiac Surgery
Neurologic complications
Incidence of 2.3% for overt clinical presentation & up to 60% when sensitive magnetic resonance imaging is applied in heart surgery of infants & children.
In control of the arch proximal to the left carotid artery, during COA surgery, this assumes that collateral blood flow and completeness of the circle of Willis allows for a favorable and even distribution of cerebral blood flow.
But patients undergoing coarctation repair, proximal occlusion of the aortic arch results in transient but significant impairment in contralateral cerebral oxygen balance

19. Blood Supply to Spinal Cord
The most important blood supply to spinal cord comes from
spinal artery, a minor supply is from Adamkiewicz artery

20. CoA Exposure

21. CoA LSCA flap

22. CoA Patch Augmentation

23. CoA Subclavian Artery Flap

24. CoA End-to-End Anastomosis

25. CoA Extended end-to-end Anastomosis

26. Coactation of Aorta Resection and Anastomosis

27. Coactation of Aorta Resection & Extended end-to-end Anastomosis

28. Coarctation of Aorta End-to-Side Anastomosis

29. Coarctation of Aorta Enlargement of VSD, Resection of Conal Septum

30. CoA + VSD, One-stage Repair

31. CoA + VSD, One-stage Repair

32. Coarctation of Aorta End-to-Side Anastomosis
Opening of Resected Segment

33. Coactation of Aorta Operative results Hospital mortality
Causes of early death are
acute and chronic cardiac failure or severe
pulmonary insufficiency
Incremental risk factor for death
1) Older age
2) Hypoplastic left heart class
3) Techniques of operation

34. Coactation of Aorta Operative results Mobidity
1) Paraplegia (0.2 ~ 1.5%)
2) Hypertension and abdominal pain
3) Persistent or recurrent coarctation
- more than 20mmHg
- high incidence in young
4) Upper body hypertension without resting gradient
- increased vascular activity in the forearm
- age at operation is risk factor
5) Late aneurysm formation
- higher in onlay patch technique
6) Valvular disease
7) Congestive heart failure with hypertension
8) Bacterial endocarditis

35. Coactation of Aorta Special features of postoperative care
1. Systemic arterial hypertension
Usually, but infant or young child doesn’t
need to be treated.
2. Abdominal pain
Usually mild abdominal discomfort for a few days,
and prominent in %.
Control hypertension, nasogastric decompression,
IV maintain
3. Chylothorax 5%

36. Coactation of Aorta Repair
Postoperative hypertension
Sealy
Altered baroreceptor response with increased excretion of epinephrine or norepinephrine
Rocchin
Sympathetic nervous system in early phase, and renin-angiotensin system in late phase

37. Coactation of Aorta Repair
Paraplegia
1. Duration of spinal cord ischemia
2. Duration of intercostal artery ischemia
3. Intraoperative proximal hypotension
4. Postoperative hypotension
5. Hyperthermia during operation
6. Anastomosis with tension
7. Acidosis in the perioperative periods

38. Coactation of Aorta Special situation & controversies
1. CoA proximal to left subclavian artery
* 1% of all COA
* reverse subclavian flap
* abdominal CoA : 0.5 ~ 2%
2. Mild or moderate coarctation
* degenerative change prone to occur
3. Prevention of paraplegia
* Collateral circulation, hypothermia(< 45min at 33 deg C)
* Descending aortic pressure under 50mmHg after clamp
4. Recurrent coarctation
Increased mortality and morbidity
5. CoA with VSD or other anomalies

39. Coactation of Aorta Balloon dilatation
The role of balloon dilatation is controversial because of early restenosis, the need for multiple interventions, potential limb ischemia, and the increased risk of aneurysm formation
The mechanism for early restenosis in neonates may be related to multiple factors including ductal tissue constriction or recoil, isthmus hypoplasia, intimal hyperplasia as a result of smooth muscle cell proliferation, and matrix protein production with arterial remodeling are involved in restenosis