Abstract 18692: Evolution of Diastolic Parameters and Their Relationship to Heart Rate in the 7-15 Week Human Fetus
Objectives: Fetal echo offers a unique opportunity to investigate cardiac function in humans from the 1st trimester. We sought to explore the evolution left ventricular (LV) diastolic parameters and their relationship to fetal heart rate (HR) from 7-15 weeks gestational age (GA).
Methods: We prospectively performed fetal echo in 137 healthy pregnancies recruited from 7+0 to 15+0 (mean 11.5±2.1) weeks GA. From Doppler studies we measured LV isovolumic relaxation time (IRT), mitral valve (MV) inflow patterns,and duration, diastolic time (IRT+inflow duration), LV ejection time (ET) and systolic time interval (isovolumic contraction time+ET). All variables were compared to GA and HR and were assessed as a proportion of the cardiac cycle length (R-R). Data were analyzed by regression and correlation analyses.
Results: Results: From 7+0-15+0 weeks, HR and GA showed a non-linear relationship (R2=0.55, p<0.001) with low HRs at 7-8 weeks, peaking between 8-9 weeks, then falling thereafter. Diastolic time linearly increased with GA (R2=0.65, p<0.001) and inversely correlated with HR (r=0.77, p<0.001). IRT showed a nonlinear inverse relationship with GA (R2= 0.70, p<0.001), but did not correlate with HR, and IRT/RR increased linearly with GA (R2=0.71, p<0.001). Both inflow duration and inflow duration/R-R linearly increased with GA (R2=0.81,p<0.001). Inflow duration inversely correlated with HR (r=-0.70) and with IRT (r=-0.71) and IRT/R-R (r=-0.83, p<0.001 for all 3). A uniphasic MV atrial systolic inflow signal was present in 20/21 fetuses at 7+1-9+0 weeks, whereas, biphasic MV inflow was seen in 45% at 9+1-10+0 , 76% at 10+1-11+0 , 95% at 11+1-13+0 and 100% after 13+1 weeks GA. Inflow duration was significantly longer (146.9±25.4 vs 85.2±12.6ms, p<0.001) and HR was lower (160±9 vs 170±10 bpm, p<0.001) in fetuses with a biphasic flow pattern. ET demonstrated a weak relationship with GA (R2=0.41) and no relationship with HR, IVRT,or IVRT/R-R, and the systolic time showed a nonlinear trend of decreasing with GA (R2=0.46).
Conclusions: In the 7-15 week fetus, improvements in relaxation suggested by decreasing IRT, decreasing HR, and, to a lesser extent, decreasing systolic time likely contribute to increasing inflow duration and to early ventricular filling.
Author Disclosures: C.M. Bohun: None. L. Howley: None. J. Serrano Lomelin: None. W. Savard: None. L. Mills: None. A. McBrien: None. D. Gyenes: None. T. Motan: None. V. Jain: None. L.K. Hornberger: None.
- © 2015 by American Heart Association, Inc.