Circumferential and radial deformation assessment in premature infants: Ready for primetime?

BACKGROUND: Speckle tracking echocardiography (STE) is a validated method to measure longitudinal deformation in premature infants, but there is a paucity of data on STE-derived circumferential and radial strain in this population. We assessed the feasibility and reproducibility of circumferential and radial deformation measurements in premature infants. METHODS: In a prospective study of 40 premature infants (<29 weeks of gestation at birth), STE-derived circumferential and radial strain, systolic strain rate (SRs), early diastolic strain rate (SRe), and late diastolic strain rate (SRa) were measured on day 2 and day 8. Intra- and inter-observer reproducibility analysis were performed using Bland-Altman analysis, coefficient of variation (COV), and intra-class correlation coefficient (ICC). The impact of a persistent patent ductus arteriosus (PDA) was analyzed. RESULTS: Deformation analysis was feasible in 98% of the acquisitions. Circumferential parameters demonstrated excellent intra- and inter-observer reproducibility with an ICC between 0.89 and 0.99 (all P < 0.001) and a COV between 4% and 13%. Radial parameters demonstrated acceptable intra- and inter-observer reproducibility with an ICC between 0.73 and 0.96 (all P < 0.001) and a COV between 14% and 27%. Infants with a PDA on day 8 (n = 21, 53%) demonstrated higher radial strain, SRs and SRe. There were no differences in circumferential parameters with a PDA at either time point. CONCLUSION: This study demonstrates clinical feasibility and reproducibility of circumferential and radial strain by STE in premature infants. A PDA elevates radial deformation measures, suggesting that the increased LV preload from a PDA may augment intrinsic contractility in the radial but not circumferential plane.