First Trimester Fetal Echocardiography: Insight Into the Fetal Circulation

Transcription

1 First Trimester Fetal Echocardiography: Insight Into the Fetal Circulation Lisa K. Hornberger, MD Fetal & Neonatal Cardiology Program Department of Pediatrics, Division of Cardiology Department of Obstetrics & Gynecology Women s & Children s Health Research Institute University of Alberta Provides an opportunity for early diagnosis at least at weeks Provides a unique opportunity to investigate the early human heart and circulation Developmental changes in fetal cardiac structure during the first trimester Developmental changes in fetal myocardial function based on Doppler parameters Developmental changes in the fetal circulation based on Doppler parameters Fetal Cardiac Embryology Dr. Mark Hill 2010: 1

2 Fetal Cardiac Embryology Human Embryo 8wks robby.nstemp.com/photo.html Fetal Cardiac Embryology Hornberger & Barrea Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu Fetal Cardiac Structure McBrien et al JASE weeks CTR largest 50-60% Midline cardiac axis Pericardial effusion Larger atria RV<LV or symmetric Ventricle width/length ratio greatest 2

3 Fetal Cardiac Structure McBrien et al JASE weeks Cardiac axis more leftward than earlier gestation but not as leftward as later gestations Pericardial effusion common Larger atria relative to total heart size Symmetry is usual Fetal Cardiac Structure McBrien et al JASE weeks CTR ~46-47% Cardiac axis ~40-45% Few with pericardial effusion Atria not as large Symmetry is usual Fetal Cardiac Structure McBrien et al JASE weeks CTR 45% Cardiac axis 50 Symmetry is usual Findings much like the midtrimester exam 3

4 Fetal Heart Rate Dubose et al obgyn.net 2011 Fetal Circulation/Heart Function Rizzo G, Arduini D, Romanini C. Umbilical vein pulsations: a physiological finding in early gestation. Am J Obstet Gynecol 1992; 167: Merce LT, Barco MJ, Bau S. Color Doppler sonographic assessment of placental circulation in the first trimester of normal pregnancy. J Ultrasound Med 1996; 15: Makikallio K, Tekay A, Jouppila P. Yolk sac and umbilicoplacental hemodynamics during early human embryonic development. Ultrasound Obstet Gynecol 1999; 14: Fetal Circulation/Heart Function Leiva MC, Tolosa JE, Binotto CN et al. Fetal cardiac development and hemodynamics in the first trimester. Ultrasound Obstet Gynecol 1999; 14: Makikallio K, Jouppila P, Rasanen J. Human fetal cardiac function during the first trimester of pregnancy. Heart 2005; 91: Wloch A, Rozmus Warcholiæska Wet al. Doppler study of the embryonic heart in normal pregnant women. J Matern Fetal Neonatal Med 2007;20:

5 Fetal Circulation/Heart Function : 360 fetal echocardiograms performed in 150 prospectively recruited healthy pregnancies, all with initial study at <14 weeks, 90 at <10 weeks Fetal Cardiac Function-Inflow Dopplers A A A A 8 Weeks 10 Weeks A A 12 Weeks 14 Weeks A A A < 10 weeks brief uniphasic AV inflow Doppler At weeks the uniphasic inflow transitioned to a biphasic inflow with appearance of low velocity E wave Increasing AV valve E/A velocity ratios demonstrated with advancing gestation (p < ) Fetal Cardiac Function-Inflow Duration F = p < Inflow duration relative to the CCL increases with gestational age 5

6 Fetal Cardiac Function 9 wks 14 wks ET ET ICT IVRT IVRT Fetal Cardiac Function-Tei Index p < (LV) Tei Index is very high at 6-7 weeks and exponentially decreases to 12 weeks then remains constant thereafter Fetal Cardiac Function - IVRT F=16.02 p < F= p < IVRT and ICT are longest relative to CCL in the mid first trimester then progressively decrease p < ultimately to plateau at weeks. 6

7 Fetal Cardiac Function-Ejection Time Ejection time relative to CCL remains constant from 7-14 weeks. Fetal Cardiac Function-IVC Flow Howley,Sekar et al Circ wks Very high a wave velocities in the IVC is 12 wks A wave the norm at less than 10 weeks. 14wks 20 wks Fetal Cardiac Function-Ductus Venosus 9wks 14wks 20wks A wave reversal is consistently present at <10 weeks; whereas after 14 weeks there is always forward flow during atrial systole in the ductus venosus 7

8 Fetal Cardiac Function-Umbilical Vein 8 wks 10 wks 12 wks 14 wks Umbilical vein flow demonstrate late diastolic (likely a wave) pulsations consistently at <10wks After 15 weeks gestation, umbilical venous pulsations no longer are present in normal pregnancies Antegrade Late Diastolic Arterial Flow Howley et al Circ 2010 In the postnatal period, antegrade late diastolic pulmonary arterial flow, occurring during atrial contraction, is a recognized feature of restrictive RV physiology ALDAF is present in both great arteries of the fetus, particularly earlier in gestation 10 week fetal MPA AV Interval Durations Howley et al Circ 2010 AV and ALDAF-V Interval Duration is longest at 7-8weeks, shortest at 10 weeks and then progressively increases to 40 weeks 8

9 Umbilical Arterial Flow 8 Weeks 10 Weeks 12 Weeks UA with absent diastolic flow in early gestation Gradual forward diastolic flow Forward continuous diastolic flow by 14 weeks 14 Weeks Conclusion Changes in Doppler flow patterns from 6 weeks to the early 3rd trimester suggest 1) Given the lack of early diastolic flow, short duration inflow, prolonged IVRT and presence of ALDAF the very early fetal myocardium is likely both more restrictive and has a reduced ability to relax both which improve with gestational age. Atrial function is potentially critical at this stage Conclusion 2) Systemic venous Doppler findings in the early fetal heart could suggest the presence of relatively high central venous pressures at least during atrial systole which decrease with gestational age but could also reflect maturational differences in atrial function & systemic venous tissue properties 3) The presence of ALDAF suggests atrial systole is not only critical for ventricular filling in the very early fetus, but also importantly contributes to early fetal cardiac output 9

10 Conclusion 4) The ejection time remains constant from 6 weeks despite significant changes in cardiac output which could be a consequence of differences in ventricular performance and loading conditions 5)Changes in UA flow reflect differences in placental versus fetal systemic vascular resistance with either high placental resistance (accepted) or low fetal systemic vascular resistance and output, the latter of which may be suggested by the presence of ALDAF 10