title: The effects of surgically treated pulmonary stenosis on lung growth and cardiopulmonary function in children during rest and exercise.
abstract: The effects of high pulmonary blood flow and pressure on pulmonary development are well understood, but the effect of low pulmonary flow/pressure is not. Pulmonary stenosis (PS) was therefore used as a model to determine its effect on lung development, which was assessed noninvasively by carbon monoxide transfer at rest and during exercise. One hundred and six control children (55 males, 8-16 yrs) and 11 children with isolated valvar or subvalvar PS surgically corrected > or =10 yrs prior to the study without residual stenosis/regurgitation were evaluated. Measurements of effective pulmonary blood flow, stroke volume, arteriovenous oxygen difference (AVO), transfer factor and transfer constant, alveolar ventilation and anaerobic threshold were performed using a mass spectrometer. Data from the normal children allowed calculation of z-scores for the study group matched for age, sex, pubertal stage and surface area. PS children at rest had a significantly lower forced expired volume in one second, cardiac frequency and transfer constant with a raised oxygen consumption and AVO which persisted on exercise. During exercise, the cardiac frequency was 12 beats x min(-1) slower and AVO 0.017 L greater than controls (p<0.05). A persistently mildly raised effective functional residual capacity (0.2 L x m(-2)) during exercise led to a reduced transfer constant (0.35 mmol x min(-1) x kPa(-1) x L(-1)), although the percentage rise (28%) from rest to peak exercise was normal. The percentage fall in stroke volume from the penultimate exercise stage to peak exercise stage was greater in PS children (24%, 95% confidence interval 11-37) than control children (2.4, -2-10, p<0.005). In conclusion, although the effects are small, pulmonary stenosis does affect cardiopulmonary function after surgery. This needs to be considered when contemplating the timing of treatment.
authors.affiliation: Dept of Paediatric Respiratory Medicine, The Royal Brompton Hospital, London, UK.
authors.forename: M
authors.initials: M
authors.lastname: Rosenthal
authors.forename: A
authors.initials: A
authors.lastname: Bush
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D002648:Child; D002675:Child, Preschool; D015444:Exercise / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008168:Lung / Q000254:growth & development*; D008297:Male; D013058:Mass Spectrometry; D011652:Pulmonary Circulation / Q000502:physiology*; D011659:Pulmonary Gas Exchange; D011666:Pulmonary Valve Stenosis / Q000175:diagnosis / Q000503:physiopathology / Q000601:surgery*; D012129:Respiratory Function Tests; D012146:Rest / Q000502:physiology; D018709:Statistics, Nonparametric; D013318:Stroke Volume / Q000502:physiology*