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Growth patterns of cardiac structures and changes in systolic time intervals in the newborn and infant. A
Insights
Cardiac dimensions in newborns grow linearly with age, except for the right ventricle, influencing the RV/LV ratio. Systolic time intervals rapidly normalize post-birth, reflecting pulmonary vascular resistance changes.
Area of Science:
- Pediatric Cardiology
- Neonatal Physiology
- Echocardiography
Background:
- Understanding normal cardiac development in neonates is crucial for identifying potential abnormalities.
- The transition from fetal to neonatal circulation involves significant hemodynamic changes.
Purpose of the Study:
- To longitudinally assess cardiac growth patterns in newborns during the first year of life.
- To analyze changes in ventricular dimensions and systolic time intervals in the neonatal period.
Main Methods:
- A longitudinal study involving 21 newborns.
- Echocardiography was used to measure cardiac structures and systolic time intervals.
- Data were collected over the first year of life.
Main Results:
- Most cardiac structures showed linear growth with age and weight.
- The right/left ventricular (RV/LV) ratio decreased parabolically with age due to unchanged right ventricular end-diastolic diameter.
- Left and right ventricular systolic time interval ratios (LVPEP/LVET and RVPEP/RVET) decreased significantly post-birth, stabilizing by the third month.
Conclusions:
- Neonatal cardiac growth follows predictable patterns, with specific changes in ventricular dimensions and systolic function.
- The rapid decrease in RVPEP/RVET reflects the physiological decline in pulmonary vascular resistance after birth.
- Echocardiography is a valuable tool for monitoring neonatal cardiac development.
Abstract:
A longitudinal study was undertaken in 21 newborns to determine cardiac growth pattern by echocardiography over the course of the first year of life. Most cardiac structures increased in size as a linear function of age and weight; however, the right ventricular end-diastolic diameter remained unchanged so that the RV/LV ratio decreased as a parabolic function of age. Left and right ventricular systolic time intervals (RVSTI, LVSTI) after birth were also studied. The ratio of left ventricular preejection period (LVPEP) to left ventricular ejection time (LVET) decreased markedly immediately after birth and subsequently remained at a constant mean value (0.30 +/- 0.04) for the rest of the study period. Right ventricular systolic time interval ratios (RVPEP/RVET) decreased rapidly and significantly during the first day of life (from a mean value of 0.39 +/- 0.08 in the first 24 hours to 0.28 +/- 0.05 on the 6th day of life). Constant values of 0.24 +/- 0.03 were found from the 3rd month of life onwards. The decrease in RVPEP/RVET in the first days of life followed a parabolic function reflecting the physiological decrease of pulmonary vascular resistance after birth.