Introduction: Aim, to defining LV mechanics, strain, rotation, and torsion in normal newborns and comparing these results to a cohort of normal adults.
Methods: 15 healthy full-term neonates without evidence of cardiac or systemic abnormalities, ages 24-48 hours, underwent echocardiography in the newborn nursery at UCSD. Exam included parasternal short axis (at the LV base, mid-LV, and apex), and apical 2- and 4-chamber views. Post-processing by speckle tracking was performed to calculate LV radial, circumferential and longitudinal strain and strain rate, as well as LV rotation and torsion (net difference between apical and basal rotation). The results were compared with data of 83 normal adults from Kaplan MC.
Results: Radial strain in neonatal LV measured approximately half compared to adults, newborn 20.3±11.0% and adult 40.6±22.8%, (p<0.001). Longitudinal strain was also significantly lower in newborns, newborn -16% and adult -23%, (P<0.001). In contrast, peak circumferential strain was similar (at the mitral valve level, newborns -17.6±5.4% adults, -19.8±4.0% (p=0.17), at the papillary muscles level, newborns -21±4.9% and adults -24±4.9% (p=0.1), and in the apical level, newborns -26.8±5.7% and adults -23.7±12.0%, (p=0.15)). The apical rotation was similar in newborns and adults (newborns 5.7±3.9°, adults 5.7±4.4°), while basal rotation was reduced in the newborns -2.3±2.9°, adults: -5.1±4.4°, (P<0.001), thereby resulting in decreased torsion in neonates compared to adults.
Conclusions: Speckle tracking measurements show that the overall LV muscular dynamics are less developed in normal neonates as compared to normal adults, with decreased radial and longitudinal strain and LV torsion.
