Effect of Ventricular Septal Defect and Patent Ductus Arteriosus on Left Ventricular Pressure in Complete Transposition of the Great Vessels

The relationship between the pressures in the left and right ventricles was examined in 80 infants and children who had complete transposition of the great vessels and in whom the presence of a ventricular septal defect or a patent ductus arteriosus was known. All children with obstruction to left ventricular outflow have been excluded. It was found that 92% (34 of 37) of the children with transposition and a ventricular septal defect had left ventricular pressures greater than 70% of the systemic, while 45% (10 of 22) of those with a patent ductus and only 5% (1 of 21) with a closed ventricular septum and no ductus, had pressures in this range. Seventy-six per cent (16 of 21) of the children in this last group had left ventricular pressures less than 50% of the systemic pressure. It is concluded that infants with transposition of the great vessels and a ventricular septal defect stand in high risk of developing obstructive pulmonary vascular disease and therapy should be guided accordingly.