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Maturational changes in left ventricular contractile state
M Toyono1, K Harada, Y Takahashi
1Department of Pediatrics, Akita University School of Medicine, Hondo, Japan.
Insights
Left ventricular contractility in premature infants is similar to full-term infants, showing preserved performance with lower afterload. This study tracked cardiac function from preterm birth through childhood.
Area of Science:
- Pediatric Cardiology
- Neonatal Physiology
- Echocardiography
Background:
- Age-related changes in left ventricular contractility are known in adults, but data on infants and children are limited.
- Understanding growth-related changes in left ventricular performance is crucial for assessing pediatric cardiac health.
Purpose of the Study:
- To evaluate left ventricular contractility changes from preterm infants to older children.
- To compare the contractility and afterload sensitivity between premature infants, full-term infants, and children.
Main Methods:
- Utilized two-dimensional and M-mode echocardiography to assess left ventricular contractility.
- Employed the rate-corrected mean velocity of fiber shortening (mVcfc) to end-systolic wall stress (ESS) relation as a contractility index.
- Analyzed data from 22 preterm infants, 23 full-term infants, and 35 children.
Main Results:
- Significant inverse linear correlations between ESS and mVcfc were observed in all groups (P<0.01).
- Premature infants and neonates exhibited significantly greater slopes and y-intercepts in the mVcfc-ESS relation compared to children.
- No significant differences in contractility were found between premature and full-term infants.
- Serial studies in premature infants showed increased ESS with growth, while mVcfc remained stable, indicating preserved left ventricular performance due to lower afterload.
Conclusions:
- Left ventricular contractility and afterload sensitivity in premature infants appear comparable to full-term infants.
- Left ventricular performance in premature infants is maintained during early life despite increasing afterload, suggesting adaptive mechanisms.
- This research provides valuable insights into the developmental trajectory of cardiac function in early life.
Abstract:
It has been suggested from animal and human studies that age-related alterations in left ventricular contractility occur. However, there is little information about growth-related changes in left ventricular performance from preterm infants to older children. In 22 preterm infants, 23 fullterm infants, and 35 children, left ventricular contractility was evaluated by two-dimensional and M-mode echocardiography. The rate-corrected mean velocity of fiber shortening (mVcfc)-end-systolic wall stress (ESS) relation was used as an index of contractility. There were significant inverse linear correlations between ESS and mVcfc in the three groups (all P<0.01). The slopes and y-intercepts of the regression lines of mVcfc-ESS relation were both significantly greater in the premature infants (mVcfc=-0.0133 ESS+1.62) and neonates (mVcfc=-0.0107 ESS+1.55) than those in the children (mVcfc=-0.0047+1.29). However, there were no significant differences between the premature and fullterm infants. Thus, these findings suggest that the contractility and afterload sensitivity of the left ventricle in the premature infants may be similar to those in the fullterm infants. In addition, our serial study in the premature infants showed that the ESS increased significantly with growth while the mVcfc did not change, suggesting that the left ventricular performance in the premature infants during early life was preserved in the setting of a lower afterload.