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Coarctation Of The Aorta

Coarctation of Aorta

1. Definition and Morphology

A. Congenital narrowing of upper descending thoracic aorta
B. Infolding of media, most prominent opposite ductus
C. > 50% narrowing needed to be significant
D. 6.5% of CHD
E. Isolated: M/F = 2:1
F. Coexisting anomalies: M/F = 1:1

2. Embryology

A. Abnormal ductal tissue with circumferential extension
B. Ductus a muscular vessel
C. In normal aorta, ductal tissue < 30% circumference
D. 95% pathology specimens with circumferential ductal tissue
E. Abnormal fetal blood flow
F. Normal fetus has decreased flow across isthmus
G. Increased incidence of coarctation with conditions that have higher ductal flow
H. Lower incidence of coarctation with conditions that have lower ductal flow

3. Coarctation Associations

A. 82% isolated lesion
B. 11% VSD's
C. 8% other cardiac abnormalities
D. 50-65% distal aortic arch narrowing
E. 27-46% bicuspid aortic valve

4. Clinical Features: Neonate

A. Heart failure after a variable time of being well
B. Delay in onset of failure related to PDA closure
C. Degree to which collaterals develop
D. Presence of major non-cardiac anomalies
E. Tachypnea, feeding difficulties, progress to acidosis
F. BP mismatch with decreased or absent femoral pulses
G. Systolic murmur L sternal border with extension posteriorly

5. Other Clinical Features Related to Age

A. Infancy: Variable clinical manifestations
B. HTN, but seldom severe
C. Cardiomegaly on CXR, RVH on EKG
D. Childhood (1-14 years): Most asymptomatic unless associated lesion
E. HTN 90%, Cardiomegaly 33%
F. Rib notching 15% (> 3 years)
G. LVH on EKG, or normal EKG in 40%
H. Adolescence/Adult: Many asymptomatic
I. HTN common and more severe
J. Murmur, decreased pulses, rib notching

6. Diagnosis'

A. Echo to visualize coarctation in neonate and infants
B. Cardiac catheterization and aortography in older patients
C. Withdrawal gradient at rest across coarctation

7. Indications for Operation

A. Neonate with severe failure, operation indicated at time of diagnosis
B. If cardiac failure or FTT not present, delay 3-6 months
C. Increased incidence of recurrent stenosis if operated at less than 3 months
D. Increased incidence of HTN if coarctation is repaired beyond infancy

8. Operative Repair

A. Resection and end-to-end anastomosis (ETE)
B. Subclavian flap aortoplasty (SFA)
C. Resection and extended end-to-end anastomosis
D. Combined end-to-end anastomosis and SFA

9. Results

A. Overall
B. Current mortality 2-10% for isolated coarctation
C. Increased mortality with
1) Distal aortic arch hypoplasia
2) Increased mortality and recurrence if < 3 months
3) Historical recurrence rates with ETE 20-40%
4) Initial results with SFA encouraging, with 10% recurrence
5) New microsurgical techniques, ETE with 10-15% recurrence
6) SFA: L arm problems, aneurysms, not appropriate in hypoplasia
7) Combined ETE and SFA

10. Persistent or Recurrent Coarctation

A. Resting peak pressure gradient > 20 mmHg
B. Incomplete resection of ductal tissue
C. Failure to extend the SFA incision distal enough
D. Balloon angioplasty and operative approaches

11. Interrupted Aortic Arch

A. Morphology and Presentation
B. 1% of all CHD
C. Type B (proximal to L subclavian) most common 55% 75% mortality at 1 month if untreated
D. Presentation
E. Critically ill infant with severe failure
F. Volume overload due to L to R shunt
G. High afterload due to closure of ductus
H. Decreased pulses, acidosis, anuria

12. Treatment and Results

A. PGE-1, oxygenation, pressors
B. If condition good - operate at first convenient time
C. If unsuitable - pressors, treat acidosis, increase CO2
D. Treatment: palliation vs. correction
E. Historical mortality 35-40%, current can be 10-15%

EXTENDED OUTLINE

1. Coarctation of the Aorta

A. General
1) occurrence rate of .2-.6 / 1000 live births
2) 5-8 % of all congenital heart disease
3) associated congenital heart lesions
a) PDA
b) VSD
c) Bicuspid Aortic valve
d) Mitral valve stenosis
B. Anatomy/ Classification
1) Anatomy depends on the age of the patient, ass. PDA, degree of arch hypoplasia
2) Group I. isolated coarctation
3) Group II. Coarctation and VSD
4) Group III. Coarctation and complex congenital heart disease
5) Other coarctations
a) pseudocoarctation: tortuous aorta but normal blood flow surgery for compression or aneurysm only
b) Abdominal coarctation: .5-2% of all coarcts
C. Embryology
1) Flow Theory - arterial size based on the amount of fetal flow - supported by ass. lesions of VSD, bicuspid aortic valve, aortic stenosis, and mitral stenosis
2) Ductal Sling Theory- ductal tissue invades the aortic wall
D. Pathophysiology
1) Bimodal presentation
a) Infants
(1) ductal dependent circulation
(2) circulatory collapse with closure of the duct
(3) treat with PGE1 , Dopamine, ventilation, and resuscitation
b) Late Presentation
(1) symptoms related to UE hypertension
(2) headaches and epistaxis
2) Mortalities
a) CHF (26% )
b) SBE (25% )
c) Aortic Rupture (21% )
d) ICH (13% )
3) untreated patients with coarctations have an average life expectancy of 35 years
E. Diagnosis
1) Infants: tachycardia, tachypnea, UE hypertension, CHF
2) Older: UE hypertension, decrease femoral pulses, rib notching
3) EHCO: best and only study needed unless complex congenital lesions are present
F. Surgical Techniques
1) General
a) Left anterolateral thoracotomy via the 4th ICS
b) maintain proximal blood pressure 160-200 mmHg to lessen the risk of paraplegia
c) maintain distal pressure of 45 mmHg
2) Resection with end to end anastomosis
a) requires significant dissection and mobilization
b) use absorbable monofilament suture
c) probably the repair of choice for infants
3) Prosthetic patch angioplasty
a) Advantages
(1) avoids extensive dissection
(2) preserves collaterals
(3) allows for simultaneous hypoplastic arch repair
(4) tension free anastomosis
(5) allows for post op growth
b) disadvantage
(1) aneurysmal formation of the opposite wall
4) Prosthetic interposition graft
a) used most often in adults especially in the presence of aneurysms, recoarctation, and long segment coarctation
5) Subclavian Flap
a) Advantages
(1) thought to have a decreased recoarctation rate esp. in neonates, recoarctation rates in long term studies show no real difference
b) controversy over whether to include the vertebra artery or not, weighing risk of Subclavian steal verses the benefit of a collateral to the left UE
6) Resection with extended end to end anastomosis
a) used in conjunction with hypoplastic arches
7) Balloon Angioplasty
a) native coarctation
(1) recommended only in high risk surgical patients
b) recoarctations
(1) 90% successful
(2) 2.5 % mortality in one study
G. Complications
1) hemorrhage
2) Post-op hypertension
a) early phase: increased sensitivity of aortic and carotid baroreceptors
b) late phase ( 48-72 hrs): secondary to increase levels of circulating renin and angiotension
c) can result in mesenteric arteritis secondary to acute inflammation, with the end result of a GI bleed
3) Paraplegia
a) incidence of .4-1.5 %
b) one study correlates a mean cross clamp time of > 49 min. and an aberrant right subclavian artery
c) prevent with short cross clamp, mild hypothermia ( 34-35 C), increased proximal pressure, and decreased distal pressure
4) Aneurysms
a) increased in patch angioplasty
b) increased in age > 15 yrs and recoarctations
5) Recoarctations
a) defined as residual gradient of > 20 mmHg
b) increased with age < 2-3 months weight < 5 Kg morphology of the coarct silk residual ductal tissue
c) end to end anastomosis may have the lowest incidence

2. Interrupted Aortic Arch ( IAA )

A. General
1) Untreated IAA has a median survival of 4 days in 90 % of infants
2) Associated congenital lesions
a) VSD 70-90%
b) Bicuspid aortic valve 30-50%
c) LVOTO 25-40%
d) Digeorge syndrome 15-30%
e) Truncas arteriosus 10%
f) TGA 3%
B. Anatomy /Classification
1) Type A: interruption distal to the SCA ( 25-35% )
2) Type B: interruption between CCA and SCA ( 60-70% )
3) Type C: interruption between the innominate and the CCA ( 5% )
C. Embryology
1) decrease flow ass. with large VSD
2) proximal arch - aortic sac
3) distal arch - fourth arch
4) isthmus - portion of the 6 th arch & dorsal arch
D. Presentation
1) most within the first days of life as duct closes
2) CHF and acidosis
3) treat with PGE1, intubation, dopamine, and, resuscitation
E. Diagnosis
1) ECHO
F. Surgery
1) Staged Correction
a) Left thoracotomy
(1) repair arch and band PA
b) 2-3 months later median sternotomy to close VSD and repair band
c) age 8-12 replace ascending/ descending conduit
2) Single Stage
a) allows for growth with direct anastomosis with autologus tissue
b) increased technical difficulty
c) watch for compression of the LPA and Let main stem bronchus
3) Surgical Technique
a) loop PA’s and ductus
b) cannulate the ascending and descending aorta via the PA
c) hypothermic arrest for repair
d) complications
e) LVOTO 24%
f) restenosis of arch 12-30%
g) mortality 20-35 %
e) increased with low birth weight, younger age, small VSD, and subaortic stenosis