title: Predictive Models for Normal Fetal Cardiac Structures.
abstract: Clinicians rely on age- and size-specific measures of cardiac structures to diagnose cardiac disease. No universally accepted normative data exist for fetal cardiac structures, and most fetal cardiac centers do not use the same standards. The aim of this study was to derive predictive models for Z scores for 13 commonly evaluated fetal cardiac structures using a large heterogeneous population of fetuses without structural cardiac defects.
  
  
  
  The study used archived normal fetal echocardiograms in representative fetuses aged 12 to 39 weeks. Thirteen cardiac dimensions were remeasured by a blinded echocardiographer from digitally stored clips. Studies with inadequate imaging views were excluded. Regression models were developed to relate each dimension to estimated gestational age (EGA) by dates, biparietal diameter, femur length, and estimated fetal weight by the Hadlock formula. Dimension outcomes were transformed (e.g., using the logarithm or square root) as necessary to meet the normality assumption. Higher order terms, quadratic or cubic, were added as needed to improve model fit. Information criteria and adjusted R2values were used to guide final model selection.
  
  
  
  Each Z-score equation is based on measurements derived from 296 to 414 unique fetuses. EGA yielded the best predictive model for the majority of dimensions; adjusted R2values ranged from 0.72 to 0.893. However, each of the other highly correlated (r > 0.94) biometric parameters was an acceptable surrogate for EGA. In most cases, the best fitting model included squared and cubic terms to introduce curvilinearity.
  
  
  
  For each dimension, models based on EGA provided the best fit for determining normal measurements of fetal cardiac structures. Nevertheless, other biometric parameters, including femur length, biparietal diameter, and estimated fetal weight provided results that were nearly as good. Comprehensive Z-score results are available on the basis of highly predictive models derived from gestational age or other biometrics as preferable for clinical reasons. These results supplant current equations and will provide a foundation for future multicenter collaborations.
authors: Children's National Heart Institute, Children's National Medical Center, Washington, District of Columbia.
authors: Anita
authors: A
authors: Krishnan
authors: Children's National Heart Institute, Children's National Medical Center, Washington, District of Columbia.
authors: Jodi I
authors: JI
authors: Pike
authors: Children's National Heart Institute, Children's National Medical Center, Washington, District of Columbia.
authors: Robert
authors: R
authors: McCarter
authors: Children's National Heart Institute, Children's National Medical Center, Washington, District of Columbia.
authors: Amanda L
authors: AL
authors: Fulgium
authors: Children's National Heart Institute, Children's National Medical Center, Washington, District of Columbia.
authors: Emmanuel
authors: E
authors: Wilson
authors: Children's National Heart Institute, Children's National Medical Center, Washington, District of Columbia.
authors: Mary T
authors: MT
authors: Donofrio
authors: Children's National Heart Institute, Children's National Medical Center, Washington, District of Columbia. Electronic address: csable@childrensnational.org.
authors: Craig A
authors: CA
authors: Sable
mesh_terms: D003198:Computer Simulation; D004452:Echocardiography / Q000592:standards*; D005260:Female; D005318:Fetal Heart / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D005865:Gestational Age; D006801:Humans; D007089:Image Enhancement / Q000592:standards; D007090:Image Interpretation, Computer-Assisted / Q000592:standards*; D008297:Male; D008955:Models, Cardiovascular; D015233:Models, Statistical; D009929:Organ Size; D017410:Practice Guidelines as Topic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000592:standards*
keywords: Cardiac parameters in the fetus; Fetal echocardiography; Z score