Left ventricular isovolumic relaxation and renin-angiotensin system in the growth restricted fetus.

OBJECTIVE To determine left ventricular isovolumic relaxation time (LV IRT) in normally developing and growth restricted fetuses (FGR) as an indicator of fetal cardiac afterload and neonatal systolic blood pressure. STUDY DESIGN A prospective longitudinal study in 124 normally developing and 47 growth restricted fetuses (FGR). LV IRT, fetal heart rate (FHR) and umbilical artery pulsatility index (PI) were determined at 2-3 week intervals starting at 22-26 weeks of gestation until delivery. Renin and angiotensin I levels were measured by radioimmunoassay in umbilical venous blood after delivery. Systolic blood pressure was measured at day 1 and day 5 of postnatal life. To evaluate the association between LV IRT, gestational age and FHR, bivariate regression analyses were performed. RESULTS Mean LV IRT (62+/-8 ms) was 29 percent longer in FGR as compared to the normal subset (47+/-6 ms) at all gestational ages (p<0.001). Mean postnatal active plasma renin level (7.78+/-S.D. 1.03 ng/ml) and postnatal angiotensin I level (4.21+/-0.70 ng/ml) in the FGR subset were significantly higher (p<0.001) than in the normal subset (4.81+/-1.04 ng/ml, renin and 2.69+/-0.44 ng/ml, angiotensin I). There was a significant difference (p<0.01) in systolic blood pressure between the two subsets on postnatal day 1 (FGR 52+/-6 mmHg vs. normal 46+/-4 mmHg) and day 5 (FGR 76+/-5 mmHg vs. normal 60+/-6 mmHg). CONCLUSION Left ventricular isovolumic relaxation time may act as a sensitive index of increased arterial afterload in the growth retarded fetus and may herald raised systolic blood pressure in the early neonatal period.

[1]  J. Manning,et al.  Postnatal modulation of prenatally programmed hypertension by dietary Na and ACE inhibition. , 2005, American journal of physiology. Regulatory, integrative and comparative physiology.

[2]  J Golding,et al.  Growth in utero, blood pressure in childhood and adult life, and mortality from cardiovascular disease. , 1989, BMJ.

[3]  R. Carey,et al.  Newly recognized components of the renin-angiotensin system: potential roles in cardiovascular and renal regulation. , 2003, Endocrine reviews.

[4]  M. Mongelli,et al.  Z‐velocity in screening for intrauterine growth restriction , 2005, Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology.

[5]  P. Steendijk,et al.  Indexes of diastolic RV function: load dependence and changes after chronic RV pressure overload in lambs. , 2002, American journal of physiology. Heart and circulatory physiology.

[6]  L. Korst,et al.  Intrauterine growth restriction is accompanied by decreased renal volume in the human fetus. , 2003, American journal of obstetrics and gynecology.

[7]  A. Baschat,et al.  The sequence of changes in Doppler and biophysical parameters as severe fetal growth restriction worsens , 2001, Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology.

[8]  D J Barker,et al.  Fetal nutrition and adult disease. , 2000, The American journal of clinical nutrition.

[9]  P. Chatelain.  Children born with intra-uterine growth retardation (IUGR) or small for gestational age (SGA): long term growth and metabolic consequences. , 2000, Endocrine regulations.

[10]  A. Wilkinson,et al.  New birthweight and head circumference centiles for gestational ages 24 to 42 weeks. , 1987, Early human development.

[11]  R. Bajoria,et al.  Placental transport rather than maternal concentration of amino acids regulates fetal growth in monochorionic twins: implications for fetal origin hypothesis. , 2001, American journal of obstetrics and gynecology.

[12]  P. Gluckman,et al.  Chronic Maternal Undernutrition in the Rat Leads to Delayed Postnatal Growth and Elevated Blood Pressure of Offspring , 1996, Pediatric Research.

[13]  M. Divon,et al.  Intrauterine Growth Retardation: Definition, Classification, and Etiology , 1992, Clinical obstetrics and gynecology.

[14]  J. Wladimiroff,et al.  Assessment of fetal left cardiac isovolumic relaxation time in appropriate and small-for-gestational-age fetuses. , 1995, Ultrasound in medicine & biology.

[15]  J. Gardiner,et al.  A standard protocol for blood pressure measurement in the newborn. , 1997, Pediatrics.

[16]  H. Drexler,et al.  The renin-angiotensin system and experimental heart failure. , 1999, Cardiovascular research.

[17]  E. Ferrazzi,et al.  Temporal sequence of abnormal Doppler changes in the peripheral and central circulatory systems of the severely growth‐restricted fetus , 2002, Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology.

[18]  D. Taylor,et al.  Human fetal kidney morphometry during gestation and the relationship between weight, kidney morphometry and plasma active renin concentration at birth. , 1996, Clinical science.

[19]  P. Gluckman,et al.  Developmental Origins of Disease Paradigm: A Mechanistic and Evolutionary Perspective , 2004, Pediatric Research.

[20]  J. Newnham.  Consequences of fetal growth restriction. , 1998, Current opinion in obstetrics & gynecology.

[21]  I. McMillen,et al.  Restriction of placental and fetal growth in sheep alters fetal blood pressure responses to angiotensin II and captopril , 1999, The Journal of physiology.

[22]  C. Romanini,et al.  Changes of Pulsatility Index From Fetal VesselsPreceding the Onset of Late Decelerations inGrowth-Retarded Fetuses , 1992, Obstetrics and gynecology.