Abstract 18692: Evolution of Diastolic Parameters and Their Relationship to Heart Rate in the 7-15 Week Human Fetus
Bibliographic record
Abstract
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.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".