Tissue doppler myocardial velocity imaging in infants and children--a window into developmental changes of myocardial mechanics.

In adults, tissue Doppler myocardial velocity imaging (TDI) is a recommended component of routine echocardiography and particularly useful to assess diastolic function of the left ventricle. In contrast, color and pulsed-wave TDI velocities are less accepted in pediatrics, perhaps due to their strong age dependence in children. This review discusses the strengths and limitations of TDI velocity imaging in the pediatric age group. Myocardial velocities increase during normal childhood heart development, starting from fetal life, and these changes vary by cardiac segment. TDI velocity maturation opens an interesting window into the normal development of myocardial mechanics in childhood, but makes it difficult to interpret data in an individual child. Moreover, there is a wider range of normal for any given pediatric age than in adults. Still, TDI has been useful to monitor systolic heart function in children with cardiomyopathy or after heart transplantation. TDI studies revealed diastolic dysfunction in obese children and in cancer survivors with preclinical anthracycline cardiomyopathy. There is a growing body of studies using TDI to assess right heart function in children with congenital heart disease or pulmonary hypertension. Another potential strength of TDI velocities is the study of myocardial dyssynchrony where color TDI is well suited for rapid pediatric heart rates, even on fetal echocardiogram. Quantitative stress echocardiography with TDI is an emerging application in children that already offered insight into heart function in children with tetralogy of Fallot. Therefore, TDI velocity imaging should become part of the routine assessment of heart function in children.