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Left ventricular rotational mechanics in early infancy: Normal reference ranges and reproducibility of peak values
Shiraz A Maskatia1, Wesley Lee2, Carolyn A Altman3
1Section of Cardiology, Department of Pediatrics, Stanford University Medical School, Palo Alto, CA, USA.
Insights
Cardiac twist and torsion mechanics in infants show acceptable reproducibility. Early infant values are comparable to premature neonates but higher than older children, with indexed torsion lower than premature but higher than term neonates.
Area of Science:
- Pediatric Cardiology
- Cardiac Physiology
- Neonatal Echocardiography
Background:
- Left ventricular (LV) twist and torsion are established measures in neonates.
- These parameters, including untwist rates and time to peak (TTP), remain undescribed in early infancy.
Purpose of the Study:
- To characterize LV rotational mechanics and timing parameters in early infancy.
- To assess the reproducibility of these measurements in infants aged 1-2 months.
Main Methods:
- Prospective enrollment of 53 term infants at 1-2 months postnatal age.
- Echocardiographic assessment of peak twist, torsion, twist rate, torsion rate, TTP values, and untwist rates by two blinded observers.
- Reproducibility evaluated using intraclass correlation (ICC) and Bland Altman analysis.
Main Results:
- High ICC (≥0.87) for peak rotational mechanics, indicating good reproducibility.
- Lower ICC (≤0.77) for TTP measures, with TTP twist rate showing the lowest ICC (0.69) and significant bias.
- Peak twist correlated modestly with global circumferential strain (R=0.52).
Conclusions:
- LV rotational mechanics and TTP measurements demonstrate acceptable reproducibility in early infancy.
- Peak twist, twist rate, and early untwist rates in infants resemble those in premature neonates and exceed those in older children.
- Indexed LV torsion in early infancy is lower than in premature neonates but higher than in term neonates.
Introduction:
Left ventricular cardiac twist and torsion values have been described in premature and term neonates, but not in early infancy. Early and late peak untwist rates and time to peak (TTP) values have not been described in infants.
Methods:
53 term infants were enrolled prospectively. The following parameters were obtained by two blinded observers at 1-2months postnatal age: peak twist and torsion (twist indexed to LV length), peak twist rate and torsion rate, TTP twist, early peak untwist rate, TTP early untwist rate, late peak untwist rate, TTP late untwist rate. Reproducibility was assessed using intraclass correlation and Bland Altman analysis.
Results:
Intraclass correlation was ≥0.87 for all peak rotational mechanics values. Measures of TTP values had intraclass correlation (ICC) values ≤0.77, with TTP twist rate demonstrating the lowest ICC (0.69). The only measure which demonstrated significant bias was TTP twist rate. Peak twist demonstrated modest correlation (R=0.52, p<0.001) with global circumferential strain, and no correlation with ejection fraction, global longitudinal strain, or left ventricular myocardial performance index.
Conclusions:
Measurements of rotational mechanics and timing to peak values have acceptable reproducibility. Peak twist, twist rate, and early untwist rate values in early infancy are similar to those reported in premature neonates, and higher than those reported in older children. Twist indexed to LV length (torsion) is lower in early infancy than in premature neonates, but higher than in term neonates.
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