to determine whether pulmonary vascular disease can be detected in infants with ventricular septal defect ( vsd ) by the presence of an increase in the frequency of the impedance modulus minimum of the pulmonary input impedance spectrum , as has been implied for older children , spectra of 25 infants ( 2 years or younger ) ( group 1 ) were compared with spectra of 20 children ( ages 2 to 7 years ) ( group 2 ) .
C0021270
infants
C0008059
children