Neonatal cardiac surgery in low and middle-income countries: importance of foetal maturation on postoperative outcomes

The number of births globally each year with a diagnosis of congenital heart disease (CHD) is estimated at around 1.3 million1; the majority of these (almost 90%) occur in low to middle-income countries (LMICs). Many of the complex operations for CHD are performed in the newborn period. While neonatal cardiac surgery comprises around 25% of the total CHD surgical volume, it accounts for more than 50% of postoperative mortality. Evidence from preclinical studies suggests that premature birth and the associated cessation of cardiomyocyte proliferation result in substantial alterations to the normal maturational processes in the newborn myocardium. An abnormal cardiac maturation trajectory ensues, which is characterised by cardiomyocyte hypertrophy, and a severalfold increase in extracellular matrix deposition in the myocardial interstium, often resulting in myocardial fibrosis.2 These changes can adversely influence contractility and conductivity of the myocardial muscle, leading to cardiac dysfunction and arrhythmia in the early postnatal period and beyond.2 When the added constraints of being born with a CHD are superimposed on these alterations, the adverse effects are likely to be magnified severalfold. An immature neonatal myocardium is more susceptible to the effects of cardiopulmonary bypass and reperfusion injury during cardiac surgery and recovers less well than an older infant’s myocardium. A recent meta-analysis3 has shown that neonates born prematurely have persistently smaller ventricular dimensions, left ventricular diastolic dysfunction that worsens with age, impaired right ventricular systolic function and an accelerated rate of left ventricular hypertrophy from the neonatal period through to childhood and adulthood. This suggests that even if an infant were to survive and be discharged from hospital after surgery, the risks were present lifelong. …