The effects of fetal blood sampling on ventricular filling patterns: differences between normally grown and growth-retarded fetuses.

The objective of this study was to evaluate the effect of fetal blood sampling on atrioventricular blood flow velocity waveforms. Flow velocity waveforms were measured from mitral and tricuspid valve immediately before and after fetal blood sampling in 25 normally grown and 10 growth-retarded fetuses. This latter group was characterized by abnormal Doppler indices in umbilical artery and middle cerebral artery suggestive of uteroplacental insufficiency as the causative factor of the impaired growth. The flow velocity parameters studied were peak velocity during early and active ventricular filling, time velocity integral, and fetal heart rate. Different indices were then calculated as expressions of ventricular diastolic function and cardiac output. In normally grown fetuses, both peak velocity during early diastole and time velocity integral values significantly increased after fetal blood sampling from both atrioventricular valves, whereas no significant changes were evidenced in the other parameters considered. Gestational age at the time of the procedure was positively related to the amplitude of these changes. In growth-retarded fetuses, fetal blood sampling induced a significant decrease in time velocity integral value form tricuspid valve, suggestive of a fall in right ventricle output. The amplitude of the decrease was significantly related to the severity of acidosis in umbilical vein. In conclusion, the cardiac hemodynamic response to fetal blood sampling differs between normally grown and growth-retarded fetuses. This difference may explain the higher rate of complications occurring in the latter group of fetuses after blood sampling.