NORMAL SIZE OF THE AOTIC SEGMENTS

• Maximum sizes are measured at the end-systole.
• Aortic and pulmonary annulus is measured at the valve level.
• Ascending aorta is measured immediately above the sinuses of Valsalva.

• Aortic isthmus is measured immediately above the entrance of the ductus arteriosus.
• Left and right pulmonary arteries are measured at their origin from the main pulmonary trunk.
• Normal Values have been reported (1).

• Diameter of aortic root on a long axis view (+/- 1.4 mm) (2):
• 16 wks – 3.2 mm
• 20 wks – 4.3 mm
• 24 wks – 5.4 mm
• 28 wks – 6.5 mm
• 32 wks – 7.6 mm
• 36 wks – 8.7 mm
• 40 wks – 9.8 mm
• Mean diameter of the aortic segments regardless of gestational age (3):
• Aortic root – 5.0 mm
• Ascending aorta – 4.4 mm
• Transverse arch – 4.1 mm
• Isthmus - 3.6 mm
• Descending aorta – 4.2 mm

REFERENCES

1. Tan J, Silverman NH, Hoffman JIE et.al. Cardiac dimensions determined by cross-sectional echocardiography in the normal human fetus from 18 weeks to term. Am J Cardiol 1992;70:459-1467.
2. Allan LD, Sharland GK et.al. Prospective diagnosis of 1006 consecutive cases of congenital heart disease in the fetus. J Am Coll Cardiol 1994;23:1452-1458.
3. Hornberger LK, Weintraub RG, Pesonen E et.al. Echocardiographic study of the morphology and growth of the aortic arch in the human fetus. Observations related to the prenatal diagnosis of coarctation. Circulation 1988;86:741-745.