Right Ventricular Function in Preterm and Term Neonates: Reference Values for Right Ventricle Areas and Fractional Area of Change

Abstract

Background Right Ventricle fractional area of change (RV FAC) is a quantitative two- dimensional echocardiographic measurement of RV function. RV FAC expresses the percentage change in the RV chamber area between end-diastole (RVEDA) to end-systole (RVESA). The objectives of this study were to determine the maturational (age- and weight- related) changes of RV FAC and RV areas and to establish reference values in healthy preterm and term neonates. Methods A prospective longitudinal study was conducted in 115 preterm infants (23-28 weeks gestational age at birth, 500-1500 gram). RV FAC was measured at 24 hours of age, 72 hours of age, 32 weeks and 36 weeks postmenstrual age (PMA). The maturational patterns of RVEDA, RVESA, and RV FAC were compared to 60 healthy full term infants in a cross sectional study (> 37 weeks, 3.5 +/− 1 kg), who received echocardiograms at birth (n=25) and one month of age (n=35). RVEDA and RVESA were traced in the RV focused apical 4-chamber view, and FAC was calculated using the formula: 100 * [(RVEDA – RVESA)/RVEDA)]. Premature infants that developed chronic lung disease or had a clinically and hemodynamically significant PDA were excluded (n=55) from the reference values. Intra- and inter- observer reproducibility analysis was performed. Results RV FAC ranged from 26% at birth to 35% by 36 weeks PMA in preterm infants (n=60) and increased almost two times faster in the first month of age as compared to healthy term infants (n=60). Similarly, RVEDA and RVESA increased throughout maturation in both term and preterm infants. RV FAC and RV areas correlated with weight (r=0.81, p<0.001), but were independent of gestational age at birth (r=0.3, p=0.45). RVEDA and RVESA correlated with PMA in weeks (r=0.81, p<0.001). RV FAC trended lower in preterm infants with bronchopulmonary dysplasia (p=0.04), but did not correlate to size of PDA (p=0.56). There was no difference in RV FAC based on gender or need for mechanical ventilation. Conclusions This study establishes reference values of RV areas (RVEDA and RVESA) and RV fractional area of change (RV FAC) in healthy term and preterm infants and tracks their maturational changes during postnatal development. These measures increase from birth to 36 weeks PMA, and this is reflective of the postnatal cardiac growth as a contributor to the maturation of cardiac function These measures are also linearly associated with increasing weight throughout maturation. This study suggests that two-dimensional RV FAC can be used as a complementary modality to assess global RV systolic function in neonates and facilitates its incorporation into clinical pediatric and neonatal guidelines.

Novel Echocardiography Methods in the Functional Assessment of the Newborn Heart

“…Although FAC is affected by loading conditions, it is less sensitive to abnormal geometry and regional abnormalities. RV FAC measurements in term and preterm infants are highly reproducible [28,44,73] . Reference values for RV RV EDA, RV ESA, and FAC have been identified in the neonatal population for both term and preterm infants [73] .…”

“…RV FAC measurements in term and preterm infants are highly reproducible [28,44,73] . Reference values for RV RV EDA, RV ESA, and FAC have been identified in the neonatal population for both term and preterm infants [73] . As expected, there is an increase in RV areas and FAC Color version available online with gestational age and a linear increase with weight [28] .…”

Right Ventricular Function in Infants with Bronchopulmonary Dysplasia: Association with Respiratory Sequelae

“…No sedation was used; infants were swaddled by parents or nursing staff. Assessments were made as described previously [9,10,12]. Table 1 summarises the various parameters studied.…”

“…Recently, investigators have established its feasibility and utility in neonates [7,8]. Additionally, given complex geometric considerations relevant to the right ventricle, fractional area change (FAC) and tricuspid annular plane systolic excursion (TAPSE) have been increasingly used to quantify RV function in infants [9,10]. …”

Longitudinal Assessment of Left and Right Myocardial Function in Preterm Infants Using Strain and Strain Rate Imaging

“…There has been recent interest in describing myocardial function in preterm infants using tissue Doppler imaging (TDI)-derived strain and strain rates [1,2,3,4,5,6]. The longitudinal systolic strain, systolic and diastolic strain rates have proven to be valuable diagnostic tools in adults, children and term infants [7,8,9,10,11].…”