Tricuspid atresia

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.

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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)

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Diagnosis:

ECG (left axis, LVH, P tricuspidale), ECHO, angiography.

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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%

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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.

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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).

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Postoperative management for tricuspid atresia:

• BT shunt
• Glenn shunt
• Fontan circulation

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

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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)

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Outcome:

• Depends on the underlying lesion; average PICU stay: 2 days

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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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