Normal values for left ventricular volume in infants and young children: questions for the authors

To the Editor: We read with interest the recent article by Lytrivi et al. and would like to thank the investigators for this important reference material. For clarification, we hope that they will respond to these questions: 1. The units of measure used for the relationship volume/(body surface area) are expressed as mL/m. Using the rule of exponents, the exponent 2 raised to the power 1.38 should result in 2 1.38 = 2.76. Could the authors explain the derivation of the exponent used in this model? 2. Inspection of the model (Figure 2) at the extreme small end (