title: Relationship between Cardiofemoral Index and the plasma concentration of brain natriuretic peptide in anemic fetuses associated with Rh alloimmunization.
abstract: BACKGROUND
  Fetal anemia is a common result of alloimmunization and is an important cause of fetal congestive heart failure resulting in heart dilation. Fetuses suspected of having heart failure present a higher Cardiofemoral Index and an increase in plasma BNP levels, because the cardiac hormonal system is activated by increased heart wall stretch due to increased left ventricular volume and pressure overload.
  
  
  METHODS
  Our group studied 33 pregnant women (22-31 weeks' gestation at the first cordocentesis) referred for intrauterine fetal transfusion due to severe red blood cells isoimmunization. Up to 6 h prior to each cordocentesis, all fetuses were submitted to ultrasonography measurements where the Cardiofemoral Index was calculated. Samples of blood from the umbilical vein were collected for hemoglobin concentration and blood gas measurements. Plasma levels of BNP were determined with the use of plasma that had previously been frozen and thawed once. Plasma BNP was measured by radioimmunoassay. Pearson's correlation test and regression analysis were used to determine the association between the plasma concentration of BNP and the Cardiofemoral Index of the anemic fetuses with RH alloimmunization.
  
  
  RESULTS
  Anemia was severe in 17 (50%) fetuses, mild in 9 (26.47%) and in 8 patients (23.53%) the fetuses were not anemic; hemoglobin ranged from 3.10 to 15.70 g/dl. The Cardiofemoral Index ranged from 0.43 to 0.87 and it was altered (>or=0.59) in 23 fetuses. A significant positive correlation was observed between BNP plasma fetal concentration and Cardiofemoral Index (Pearson r=0.61, P<0.0001).
  
  
  CONCLUSIONS
  These results suggest that fetal plasma concentration of BNP may increase in fetuses with heart dilation leading to a positive association between Cardiofemoral Index and plasma concentration of BNP.
authors.affiliation: Fetal Medicine Center, Obstetrics and Gynecology Department, Federal University of Minas Gerais, Belo Horizonte, Brazil. anapenido@oi.com.br
authors.forename: Ana Luíza Penido
authors.initials: AL
authors.lastname: Ferreira
authors.forename: Zilma Silveira Nogueira
authors.initials: ZS
authors.lastname: Reis
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Braga
authors.forename: Henrique Vitor
authors.initials: HV
authors.lastname: Leite
authors.forename: Antônio Carlos Vieira
authors.initials: AC
authors.lastname: Cabral
mesh_terms: D000328:Adult; D000740:Anemia / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D003430:Cross-Sectional Studies; D005260:Female; D005269:Femur / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D005315:Fetal Diseases / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005333:Fetus; D006352:Heart Ventricles / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D011247:Pregnancy; D012203:Rh Isoimmunization / Q000097:blood*; D018709:Statistics, Nonparametric; D016216:Ultrasonography, Prenatal; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D020097:Natriuretic Peptide, Brain