Response to Letter Regarding Article, “Implications of Early Aortic Stiffening in Patients With Transposition of the Great Arteries After Arterial Switch Operation”

We thank Drs Kharabish and Fratz for their comment on and question about whether the observed difference in aortic distensibility truly reflects a difference in bioelastic properties rather than being confounded by the larger lumen area near the aortic root. We would like to point out several aspects that run counter to such a line of thought:1. The suggestion that distensibility generally decreases with increasing cross-sectional area when stroke volume and bioelastic properties remain unchanged is incorrect. The physical quantity that causes the area change for a vessel with given bioelastic properties is the pulse amplitude. Vessel distensibility is commonly defined as the …