Serial studies of pulmonary stenosis in infancy and childhood.

Thirty-five children with pulmonary stenosis were catheterized from 1 day to 9 years of age and recatheterized after 2 weeks to 15 years. Right ventricular systolic pressure rose in 24 and the increase was greater in those under than over 5 years old. Pulmonary valve orifice area per square metre of body surface area increased in 12, but did not change in 3, and fell in 17; absolute decrease in calculated orifice area was usually associated with infundibular hypertrophy. Increase in right ventricular systolic pressure with age was thus caused by failure of the valve orifice to grow fast enough to keep pace with the increase of stroke volume. In the whole group, increasingly severe pulmonary stenosis was matched by increasing electrocardiographic evidence of right ventricular hypertrophy. However, in individual patients the electrocardiogram could suggest that right ventricular pressure had decreased when in fact it had risen considerably.