Definition: wide morphological spectrum with mild aortic stenosis (AS) to HLHS.
Most common is valvular AS (70 – 80%), followed by subvalvular AS (10 – 20%) and supravalvular AS (rare), which is common in Williams Syndrome (1:20.000 live births: mental retardation, behavioural traits, elfin facies with AS and peripheral PA stenosis).
All LVOTO can be associated with other defects.
LVH due to increase in afterload, subendocardial ischemia leading to coronary ischemia with cardiomyopathy; reduced blood fow through LVOT leading to hypoplasia of mitral valve, LV and aortic arch.
ECG (left axis, LVH), ECHO.
In critical AS there is early presentation with cardiogenic shock when PDA closes.
In mild forms: failure to thrive, increased WOB.
Only 15% present under age 1yr.
Management preoperatively with critical AS:
- PGE1 infusion (20ng/kg/min) to maintain PDA patency for systemic perfusion
- Intubation and ventilation as required
- Milrinone (0.25-0.5 mcg/kg/min) and noradrenaline (0.02-0.1 mcg/kg/min) to improve CO, avoid β-adrenergic drugs (worsening diastolic dysfunction, tachycardia)
ECG, CXR, CUS, FBE, clotting, UEC, PRBC (4), FFP (2), platelets (2), cryoprecipitate (2).
Methylprednisolone 10mg/kg 12hrs and 6hrs pre surgery in neonates.
Dependent on morphological structures, development of LV and LVOT and associated defects (aortic root and mitral valve diameter, LV/RV ratio).
Single ventricle pathway (HLHS) or two-ventricle surgery for AS: surgical valvotomy, percutaneous balloon valvotomy, dilation of LVOTO (Konno procedure) and/or aortic valve replacement with pulmonary autograft and pulmonary homograft (Ross procedure) or combined Ross-Konno procedure.
- Keep intubated, ventilated, sedated and paralysed for 24-48 hrs
- Inotropes: milrinone plus dopamine or adrenaline (plus noradrenaline, aim MAP >40 mmHg in neonates)
- Haemodynamics: SBP >60 mmHg, MAP >40 mmHg (increasing over time), LAP 8-12 mmHg, CVP 8-12 mmHg
- Respiratory: normoxaemia, normocapnea
- Fluid restriction: 1ml/kg/hr, trophic feeds
- Low CO: keep paralysed, don’t wean inotropes <24 hrs
- Anatomical coronary artery problems (check ECG, troponin) → early investigation (ECHO, Cathlab)
- Coronary artery spasm: start GTN 5-10 mcg/kg/min
- Arrhythmia: SVT (adenosine, digoxin), JET (slow amiodarone), bradycardia (pacing), AV block (pacing)
- Low urine output: start PD
- Severe AI (15-20%) mainly in balloon valvotomy
- Residual AS
- No anticoagulation required in Ross-Konno procedure (in valved conduits consider anticoagulation)
- Depending on the underlying lesion; average PICU stay: 5-8 days
- Pulmonary homograft needs reoperation with age
- Autograft may develop AI
 Critical Heart Disease in Infants and Children; 2nd ed, Nichols et al: Left Ventricular Outflow Obstruction
 J Thorac Cardiovasc Surg. 1966 Apr;51(4):484-92: Cornell et al: Supravalvular aortic stenosis
 Eur J Cardiothorac Surg. 2007 Jun;31(6):1013-21: Alsoufi et al: Management options in neonates and infants with critical left ventricular outflow tract obstruction
 Circulation. 2006 Nov 28;114(22):2412-22: Aboulhosn et al: Left ventricular outflow obstruction: subaortic stenosis, bicuspid aortic valve, supravalvar aortic stenosis, and coarctation of the aorta
 Ann Thorac Surg. 2003 Nov;76(5):1398-411: Brown et al: Surgery for aortic stenosis in children: a 40-year experience
 J Card Surg. 2012 Jan;27(1):103-11. Anagnostopoulos et al: Surgical management of left ventricular outflow tract obstruction
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