The examination of infants and toddlers should take place with the patient on the mother's knee, only later moving the child on to the couch. An initial attempt at auscultation through the clothing enables the child to get used to the stethoscope, and a count of the resting heart rate to be obtained. Giving the child a toy to hold may help. Timing of systole by palpation of the carotid pulse, it is wise to begin auscultation in the second left intercostal space where the two components of the normal second sound are best heard.
A split first sound is often heard, and is normal at the lower left sternal border. Physiological splitting of the second sound (P2 after A2) is most significant on inspiration. A2 is louder than P2 in pulmonary stenosis (P2 is soft and delayed), but P2 is as loud or louder than A2 in a secundum ASD or pulmonary hypertension. Splitting of A2 and P2 excludes truncus arteriosus or pulmonary atresia, but a single sound may be heard in a VSD with pulmonary hypertension, or tetralogy of Fallot.
A venous hum increases on inspiration and disappears in the head down posture, and is thereby differentiated from the continuous murmur of a ductus. The child should not only be listened to in the prone position, but rolled onto his left side for the appreciation of a mid-diastolic murmur at the apex, and sat up and leaned forward for the blowing early murmur of aortic incompetence.
Last reviewed 01/2018