Fetal Cardiac function Juriy Wladimiroff, MD, PhD, FRCOG, FCNGOF, FEBCOG, FISUOG, FAIUM, FAOGU, Dr h.c.

Cardiovascular studies in the human fetus What happens to fetal cardiac performance in: I) Manifest fetal growth restriction: AC and estimated fetal weight < 5th centile; II) Diminished fetal growth: AC and estimated fetal weight still within the normal range: between 5th and 95th centile.

Fetal growth restriction is associated with centralization of the arterial circulation and preferential flow to heart,brain and adrenals. Changes in the umbilical flow velocity waveform may act as a warning sign rather than an indication for obstetric intervention. Fetal venous (ductus venosus) flow changes result from cardiac compromise reflecting fetal hypoxaemia and acedaemia.

Moderate arterial redistribution, early venous changes Severe arterial redistribution with late venous changes

Having described the changes in the fetal extra-cardiac circulation, notably in UA and DV, what happens at fetal cardiac level? Myocardial performance index (MPI) and mechanical P-R interval in SGA and FGR

Left ventricle RV R LV L MV RA LA

Color Doppler not mandatory but its use is helpful RV LV RA LA LV AoA RV AoD

Myocardial performance Index (MPI) and mechanical P-R interval in SGA and FGR MPI : (ICT + IRT) / ET : cardiac contraction force Mechanical P-R interval: time interval between onset MV A-wave and onset ET: cardiac A-V conductance 71 women between 24 and 32 weeks SGA: fetal AC < 5th centile + normal peripheral Dopplers (n =11); FGR: fetal AC <5th centile + abnormal UA PI (n =12)

CONCLUSIONS SGA and FGR fetuses demonstrate altered cardiac function in the late 2nd and 3rd trimester of pregnancy; MPI is raised in SGA fetuses before arterial and venous Doppler abnormalities that characterize hypoxia are evident; The majority of SGA fetuses with raised MPI developed abnormal umbilical artery PI within the following two weeks; Cardiac conductance does not change in SGA or FGR

DIMINISHED FETAL GROWTH WITHIN THE NORMAL FETAL WEIGHT RANGE FGR: fetal abdominal cicumference < 5th centile Manifest FGR is preceded by a period of diminished fetal growth within the normal fetal weight range. Not much is known about adaptive haemodynamic mechanisms during this stage of reduced fetal growth. Insight in changes ocurring in the fetal circulation preceding manifest FGR may improve our understanding of compensatory mechanisms in response to an adverse fetal environment.

Diminished fetal growth within the normal fetal weight range Aim of the study: to evaluate whether reduced fetal growth is associated with adaptive fetal cardiovascular changes. Population-based prospective study 1215 women; 28-34 weeks; cross-sectional study design Gestational age adjusted sds (z-score) were developed. Fetal weight was categorised in ten groups according to deciles of SDs of estimated weight, indicating small (group 1) to large (group 10) for gestational age fetuses

Uterine artery RI & Umbilical artery PI

Left ventricular cardiac output (ml/min)

Right ventricular cardiac output (ml/min)

Combined cardiac output (ml/min) & Ratio cardiac output left/right

Ductus venosus PIV

CONCLUSIONS: FETAL HAEMODYNAMIC PATTERNS ALREADY CHANGE IN THE PRESENCE OF REDUCED FETAL GROWTH WHILST STILL WITHIN THE NORMAL ESTIMATED WEIGHT RANGE.

Conclusions Decreased fetal growth is associated with adaptive fetal cardiovascular changes. Cardiac remodeling and cardiac output changes are consistent with a gradual increase in afterload and compromised arterial compliance in conditions of decreased fetal growth. These changes already occur before the stage of clinically apparent fetal growth restriction and may contribute to the increased risk of cardiovascular disease in later life.

Thank you

UMBILICAL ARTERY FLOW VELOCITY WAVEFORMS: NORMAL > ABNORMAL 1 2 4 3

DUCTUS VENOSUS: ABNORMAL WAVEFORM