Position of heart in relation to sternum and nipple line at various ages.

Frontal X-ray pictures of 210 healthy children from birth to twelve years of age with radio-opaque markers at sternal ends and both nipples were reviewed. The position of centre of cardiac silhouette was correlated with sternal areas and internipple line. The heart was found to descend with age, its centre lying beneath mid-sternum during first six months of life and beneath lower sternum after infancy (p less than 0.001). The position did not vary with age in relation to internipple line (p greater than 0.05). In 77.6% of all children, it was below the internipple line and in 22.4% above or at the internipple line. Because of the erratic relationship of cardiac centre with internipple line, the latter should not be considered a landmark for cardiac position. External cardiac massage should be applied in relation to sternum and at different locations according to the age. Sites for optimal compression have been suggested. No sexual dimorphism was observed.