Size and shape of the four-chamber view of the fetal heart in fetuses with an estimated fetal weight less than the tenth centile.

Background: Fetuses with an estimated fetal weight below the 10 centile have an increased risk of adverse perinatal and long-term outcomes as well as increased rates of cardiac dysfunction, which often alters cardiac size and shape of the 4-chamber view and the individual ventricles. As a result, a simple method has emerged to screen for potential cardiac dysfunction in fetuses with estimated fetal weights <10 centile by measuring the size and shape of the 4-chamber view and the size of the ventricles.

Objective: To determine the number of fetuses with an abnormal size and shape of the 4-chamber view and size of the ventricles in fetuses with an estimated fetal weight <10 centile.

Materials And Methods: This was a retrospective study of 50 fetuses between 25 and 37 weeks of gestation with an estimated fetal weight <10 centile. Data from their last examination were analyzed. From an end-diastolic image of the 4-chamber view, the largest basal-apical length and transverse width were measured from their corresponding epicardial borders. This allowed the 4-chamber view area and global sphericity index (4-chamber view length/4-chamber view width) to be computed. In addition, tracing along the endocardial borders with speckle tracking software enabled measurements of the right and left ventricular chamber areas and the right ventricle/left ventricle area ratios to be computed. Doppler waveform pulsatility indices from the umbilical (umbilical artery pulsatility index) and middle cerebral arteries (middle cerebral artery pulsatility index) were analyzed, and the cerebroplacental ratio (middle cerebral artery pulsatility index/umbilical artery pulsatility index) computed. Umbilical artery pulsatility indices >90 and cerebroplacental ratios <10 centile were considered abnormal. Using data from the control fetuses, the centile for each of the cardiac measurements was categorized by whether it was <10 or >90 centile, depending upon the measurement.

Results: Of the 50 fetuses with estimated fetal weight <10 centile, 50% (n = 25) had a normal umbilical artery pulsatility index and cerebroplacental ratio. These fetuses had significantly more (P < 0.02 to <0.0001) abnormalities of the size and shape of the 4-chamber view than controls. In all, 44% had a 4-chamber view area >90 centile, 32% had a 4-chamber view global sphericity index <10 centile, 56% had a 4-chamber view width >90 centile, and 80% had 1 or more abnormalities of size and/or shape. The remaining 50% of fetuses (n = 25) had abnormalities of 1 or both for the umbilical artery pulsatility index and/or cerebroplacental ratio. These fetuses had significantly higher rates of abnormalities (P <0.05 to <0.0001) than controls for the following 4-chamber view measurements: 36% had a 4-chamber view area >90 centile; 28% had a 4-chamber view global sphericity index <10 centile; and 68% had a 4-chamber view width >90 centile. Only those fetuses with an abnormal umbilical artery pulsatility index had significant changes in ventricular size; 56% had a left ventricular area <10 centile; 28% had a right ventricular area <10 centile; 36% had right ventricular/left ventricular area ratio >90 centile. One or more of the above abnormal measurements were present in 92% of the fetuses.

Conclusion: Higher rates of abnormalities of cardiac size and shape of the 4-chamber view were found in fetuses with an estimated fetal weight <10 centile, regardless of their umbilical artery pulsatility index and cerebroplacental ratio measurements. Those with a normal umbilical artery pulsatility index and an abnormal cerebroplacental ratio had larger and wider measurements of the 4-chamber view. In addition, the shape of the 4-chamber view was more globular or round than in controls. These fetuses may have an increased risk of perinatal complications and childhood and/or adult cardiovascular disease. Screening tools derived from the 4-chamber view, acting as surrogates for ventricular dysfunction, may identify fetuses who could benefit from further comprehensive testing and future preventive interventions.