Interrupted aortic arch
Definition:Â obstructive anomaly of the aortic arch.
Classification by Celoria et al:
Type A (20%): IAA distal to left subclavian artery.
Type B (78%): between left subclavian and left carotid artery.
Type C (2%): proximal to left carotid artery.
Most of them are associated with a VSD or other defects.
Prevalence 1% of all CHD. Incidence 4:10.000 of all life births. Genetic association to Di-George-Syndrome.
Physiology:
With PDA closure there is an acute increase in LV afterload, a decreased CO, increased LVEDP. Â This leads to CCF (in extreme: myocardial ischemia) and shunt reversal along the PFO (and VSD if present). Â This in turn causes increased PBF and severe CCF with systemic hypotension.
Diagnosis:
Hypertension of upper limbs is usually not present before Day 5, but usually after PDA closure with signs of CCF of various degree.
ECG: signs of RVH.
CXR: cardiomegaly and pulmonary congestion.
ECHO
Cardiac catheterisation (diagnostic and interventional)
MRI
Preoperative management:
- Commence Prostaglandin E1 (20ng/kg/min) to maintain systemic perfusion. Intubate and sedate to lower the oxygen consumption. Hypoventilation to higher the PVR and to lower the SVR.
- Balanced circulation with PDA open and/or VSD present (aim SpO2 75-85%)
- Dopamine (5-10 mcg/kg/min), dobutamine (5-10 mcg/kg/min) or adrenaline (0.02-0.1 mcg/kg/min) may be required to stabilise for a low CO
- Careful fluid resuscitation – this is an obstructive lesion, not hypovolaemic!
- Calcium infusion if there is Di-George Syndrome (see inotropes)
Preoperative preparation:
ECG, CXR, CUS, FBE, xlotting, UECs, FISH, PRBC(4), FFP (2), platelets (2), cryoprecipitate (2).
Methylprednisolone 10mg/kg 12hrs and 6hrs pre surgery in neonates.
Surgery:
Preferred single stage repair with end-to-end or end-to-side anastomosis, patch augmentation, subclavian-flap aortoplasty or extended resection with primary anastomosis and also VSD closure.
Postoperative management:
- Keep intubated, ventilated, sedated and paralysed for 24 hours for patients with preceding high PBF; elective cases can be extubated earlier
- Inotropes: milrinone plus dopamine
- Haemodynamics: age adjusted, in neonates: SBP >60 mmHg but <80 mmHg; MAP >40 mmHg; prevent hypertension (SNP or Esmolol infusion)
- Respiratory: normoxaemia, normocapnea
- Fluid restriction: 1ml/kg/hr, careful trophic feeds
- Haemostasis: Hb 100-140
- Maintain normothermia
Specific problems:
- Acute hypertension (increase of noradrenaline release due to sympathetic stimulation during repair): SNP or Esmolol infusion
- Postcoarctectomy syndrome:Â hypertension, abdominal pain, ileus (2-3 days post repair)
- PHT if high PBF was preceding (VSD or ASD)
- Thoracic duct injury with chylothorax
- Laryngeal nerve injury
- Spinal cord injury (spinalis anterior injury): 0.4-1.5%
- Neurological injury due to deep hypothermic circulatory arrest
Outcome:
Perioperative mortality: 5-7%
Recoarctation: 5-50%
Long term antihypertensive treatment required in 30%.
Long term survival after 10 yrs: 94% (IAA and VSD); 72% (IAA and TGA). 5 yrs: 47% (IAA and other defects)
References:
[1] Critical Heart Disease in Infants and Children; 2nd ed, Nichols et al: Interrupted Aortic Arch
[2] Eur J Cardiothorac Surg. 2009 Apr;35(4):565-8: Kobayashi et al: Outcomes following surgical repair of aortic arch obstructions with associated cardiac anomalies
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