Normal reference ranges for cardiac valve cross-sectional areas in preterm infants.

Sir,

I have two comments on the interesting the study by Abushaban et al. on the normal reference ranges for cardiac valve cross-sectional areas (CSAs) in preterm infants in Kuwait.[1]

First, the authors found on employing echocardiography that all cardiac valve CSAs correlated well with body weight and a significant gradual increase was observed in all valve CSAs with body weight during each period of life. Overall, a progressive and significant increase in all valve CSAs was observed during the first 9 weeks of life. The authors provided reference data, which can be used as a normal reference tool for valve CSAs in preterm infants against gestational age, body weight, and chronological age.[1] The authors addressed few limitations. They used the continuity equation to calculate valve CSAs, which sometimes alters due to changes in hemodynamics. Moreover, the continuity equation method might be more complicated for clinical use, and they did not correlate the results obtained using this method with those obtained using other methods.[1] I presume that the following limitation is additionally contributory and might cast some suspicions on the study results and their constructed reference values. In the methodology, the authors stated that the studied babies were from a mixed population (most were Arabic, and the remainder were from other Asian nations).[1] This point is important to be considered as many echocardiographic parameters have been found to vary among different ethnic groups[2] and construction of ethnic-appropriate echocardiographic reference values is needed to be employed in the clinical settings and research field for a given population.[3]

Second, it is explicit that cardiovascular magnetic resonance (CMR) is considered the gold standard method for the assessment of cardiac structure and function and it permits the differentiation between normal and pathological states. Interestingly, CMR-specific reference ranges for various cardiac parameters have been constructed for certain populations.[4] To precisely construct the normal reference ranges for cardiac valve CSAs in preterm infants in Kuwait, CMR employment in a large scale multicenter study is suggested.

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Conflicts of interest

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