Torsion of young hearts: a speckle tracking study of normal infants, children, and adolescents

Abstract

Our aim was to study the rotational mechanics of the heart in a special population including neonates, young children, and adolescents. We showed the effect of age on torsion and the different rotational variables. This study is the first that focuses on neonatal heart mechanics. We recruited 70 normal children between few hours and 18 years old. We excluded abnormal rhythm and function. Short-axis parasternal views were taken at the base of the heart and the apex. Using the speckle tracking technique, we analysed the rotation curves at apex and base and calculated the net twist and torsion of the left ventricle (LV). We also calculated the twist and untwist rates to get the correlation with age and body surface area (BSA). Rotational patterns during diastole also were studied. Deformational time delay between the base and the apex was looked up. Apical rotation and net twist increased with age significantly (r = 0.41 and 0.38, respectively, P = 0.001) but when normalized by LV length there was fixed torsion among age groups. Rotation velocity declined with ageing during systole and diastole for both base and apex (r = -0.58 and -0.62 for twist rate, -0.69 and -0.6 for untwist rate, respectively, P < 0.001). Concordant results were reported for BSA. Deformational delay was decreasing with age (r = -0.74 for systolic and -0.53 for diastolic, P < 0.001). Infants hearts tend to deform more and faster than other groups. While apical twist and net twist increase with age, torsion is fixed among age groups. In young hearts, torsion is the result of differential twist.