The spectrum of pulmonary input impedance in children with complete transposition after the arterial switch operation

Abstract

AbstractWe evaluated the physical characteristics of the pulmonary trunk in 32 patients with complete transposition after the arterial switch operation, calculating the pulmonary input impedance. In 6 of the patients, the characteristic impedance was equal to, or less than, the value in patients with ventricular septal defect. In those patients with an intact ventricular septum, or those with a ventricular septal defect who had undergone the arterial switch operation or banding of the pulmonary trunk before 3 months age, the frequency of the first modulus minimum also agreed with the values obtained in patients with ventricular septal defect. The value was high, however, in patients with complete transposition with ventricular septal defect who had undergone an arterial switch operation or banding of the pulmonary trunk after 4 months of age. Our data suggest decreased distensibility of the proximal pulmonary trunk after the arterial switch operation, and mild changes in the pulmonary vasculature in patients with complete transposition with ventricular septal defect who had undergone either an arterial switch operation or banding of the pulmonary trunk after 4 months of age. Long-term follow-up is needed clarify whether or not these features affect right ventricular function by means of an increase in afterload.