Changes in left ventricular diastolic flow dynamics in the neonatal transition period and beyond.

Significant hemodynamic changes occur within the neonatal transition period including a sudden increase in pulmonary blood flow, disappearance of fetal shunts, and increase in systemic vascular resistance. How this affects left ventricular (LV) physiology and intraventricular flow dynamics is still poorly understood. Blood speckle tracking is a novel high frame rate echocardiographic technique that allows to visualize two-dimensional intraventricular flow dynamics. In this study, longitudinal changes in LV diastolic flow dynamics were explored in a prospective single-center design analyzing a total of 176 echocardiographic examinations in 36 healthy newborns from birth until 6 mo of age. Kinetic energy, energy loss, vorticity, and intraventricular pressure difference increased significantly from birth until 6-8 wk of age (P < 0.001 for all parameters). The increase in intraventricular pressure difference continued until 6 mo of age, whereas no further significant changes in the other quantitative LV flow parameters could be observed beyond 6-8 wk. Early after birth, diastolic vorticity was predominantly located at the anterior mitral valve leaflet whereas at 6 mo of age, vorticity was similar at the anterior compared with the posterior mitral valve leaflet. Overall, these results indicate that LV diastolic physiology and flow dynamics undergo substantial changes in early life. The observed changes in diastolic LV properties are likely associated with increased LV filling in the presence of increased pulmonary blood flow.NEW & NOTEWORTHY Assessment of left ventricular flow dynamics is highly feasible using high-frame rate echocardiography-based blood speckle tracking. In healthy newborns, left ventricular diastolic kinetic energy, energy loss, and vorticity significantly change during the first weeks, stabilizing after 6-8 wk, whereas intraventricular pressure difference continues to increase until 6 mo of age. These findings indicate that intraventricular flow dynamics can describe changes in cardiac physiology contributing to normal postnatal cardiovascular adaptation, maturation, and function.