Definition: complete obstruction RA → RV (muscular TA, membranous, valvular TA and Ebstein’s anomaly) with presence of PFO/ASD, VSD, and increased mitral valve annulus, leading to hypertrophic LV and hypoplastic RV.
Physiology:
Depends on the position of great arteries and the VSD physiology:
60% normal great arteries with restrictive VSD and pulmonary stenosis or atresia causes decreased PBF and cyanosis (PBF depending on VSD and PDA)
10% normal great arteries with unrestrictive VSD causes increased PBF and CCF
30% with D-TGA (10% with pulmonary stenosis or atresia, 20% without pulmonary stenosis)
Diagnosis:
ECG (left axis, LVH, P tricuspidale), ECHO, angiography.
Management preoperatively:
With decreased PBF:
- PGE1 infusion (20 ng/kg/min) to maintain PDA patency
- BAS or blade septostomy in older children if ASD restrictive
- Intubation and ventilation, hence lowering PVR
- Aim for SpO2 75 – 85%
With increased PBF:
- Anticongestive treatment
- Aim for SpO2 75-85%
Preoperative preparation:
ECG, CXR, CUS, FBE, clotting, UECs, PRBC (4), FFP (2), platelets (2), cryoprecipitate (2).
Methylprednisolone 10mg/kg 12 hrs and 6 hrs pre surgery in neonates.
Surgery:
Dependent on anatomical associations and PBF:
With decreased PBF: BT-Shunt or a modified BT Shunt in newborns
With increased PBF: PA banding (careful in subaortic obstruction!) or Damus-Kaye-Stansel (end-to-side anastomosis PA to the ascending aorta) for patients with LVOTO; in older children: bidirectional Glenn shunt or total-cavopulmonary connection (Fontan).
Postoperative management for tricuspid atresia:
Postoperative management for TA and PA banding:
- Commence morphine sedation, paralyse with cisatracurium for 12 hrs until pulmonary and systemic blood flow have balanced
- Respiratory: SpO2 75 – 85%, may need some time to settle pulmonary blood flow and achieve stable saturations
- Inotropes: usually not required
- Haemodynamics: SBP >60 mmHg, MAP >40 mmHg, increasing over time, LAP 8-12 mmHg, CVP 8-12 mmHg
- Fluid restriction: 3 ml/kg/hr, early feeds if stable
- Haemostasis
Specific problems:
- Persistent low SpO2 indicate a too tight PA band (differential diagnosis: hypovolaemia, low CO)
- Persistent high SpO2 indicate a too loose band → child is growing into it; manipulate Qp:Qs by pH (acidosis), pO2 (decrease FiO2), pCO2 (mild hypercapnoea), systemic vasodilators (SNP)
Outcome:
- Depends on the underlying lesion; average PICU stay: 2 days
References:
[1] Critical Heart Disease in Infants and Children; 2nd ed, Nichols et al: Tricuspid Atresia
[2] Surg Gynecol Obstet 1952;95:213: Muller et al: The treatment of certain congenital malformations of the heart by the creation of pulmonic stenosis to reduce pulmonary hypertension and excessive pulmonary blood flow: a preliminary report
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