Effect of respiration on the echocardiogram in children with cystic fibrosis.

Respiration-related cyclic variation was noted in echocardiographic measurements of right and left ventricular end-diastolic dimension. D-E amplitude of the anterior mitral leaflet, and mitral valve E-F slope in 26 children with cystic fibrosis. The observed echographic changes seem to be an exaggeration of the normal physiologic variation seen with respiration. In children with advanced respiratory disease, airway obstruction, rather than cor pulmonale, may be responsible for this exaggeration.