Circulating megakaryocytes and platelet production in children with congenital cardiac defects undergoing cardiac catheterisation.

The literature has recently focused attention on the lung as a source of platelet production. Thirty-two children with normal lungs admitted to hospital for investigation of congenital heart disease were studied with the intention of showing a relationship between left atrial platelet counts and pulmonary blood flow. This was not demonstrated. Mean platelet counts were 296 X 10(9)/l (right atrium) and 304 X 10(9)/l (left atrium). There was no significant difference between the two results. It is suggested that previous studies were performed on subjects with significant acquired disease and that in young children with no pulmonary disease the lung is not a major source of platelet production.