Normal reference ranges for aortic diameters in preterm infants.

Objective: To establish normal reference ranges and Z -scores for aortic diameters in preterm infants according to the body surface area and assess their correlation with body weight, body surface area, and gestational age.

Patients and methods: In a prospective study, 268 preterm infants who fulfilled the criteria for inclusion were examined. Echocardiograms were performed to measure the ascending aorta, transverse aorta, and aortic isthmus diameters on 0 days to 6 days of life and at weekly intervals until the babies reached 36 weeks. Body surface area was divided into 13 groups from 0.07 m2 to 0.19 m2 .

Results: The mean gestational age was 29.8 [± 2.38 standard deviation (SD)] weeks, ranging from 24 weeks to 35 weeks. The mean body weight was 1479 (± 413 SD) g, ranging from 588 g to 3380 g, and the mean body surface area was 0.13 m2 , ranging from 0.07 m2 to 0.19 m2 . All the aortic diameters correlated well with both body weight and body surface area. Reference ranges with the mean ± SD, range, and Z -scores were calculated for aortic diameters according to the body surface area. A significant gradual increase was observed in ascending aorta, transverse aorta, and aortic isthmus diameters with increasing body surface area. Overall, a progressive and significant increase in ascending aorta, transverse aorta, and aortic isthmus diameters was observed during the first 9 weeks of life.

Conclusion: The ascending aorta, transverse aorta, and aortic isthmus diameters exhibited a significant correlation with the body surface area and body weight. This study provides reference data with Z -scores that can be used as a normal reference tool for the ascending aorta, transverse aorta, and aortic isthmus diameters for preterm infants based on the body surface area.