What is the normal chest-to-height ratio for children?

Patient's question:

3-year-old chest-to-heart ratio 0.54, cardiomegaly, normal ultrasound

Doctor's answer:

The upper normal limit of the cardiothoracic ratio (CTR) for children aged 3-7 years is 0.55. The increase in the transverse diameter of the child's heart is related to weight, age, and height growth, with weight being the most closely related factor, followed by age. The cardiothoracic ratio is unrelated to age and gender.
Guidance: The upper normal limit of the cardiothoracic ratio (CTR) for children aged 3-7 years is 0.55. The increase in the transverse diameter of the child's heart is related to weight, age, and height growth, with weight being the most closely related factor, followed by age. The cardiothoracic ratio is unrelated to age and gender.