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 veloc ity waveforms were measured from mitral and tricuspid valve immediatel y before and after fetal blood sampling in 25 normally grown and 10 gr owth-retarded fetuses. This latter group was characterized by abnormal Doppler indices in umbilical artery and middle cerebral artery sugges tive of uteroplacental insufficiency as the causative factor of the im paired 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 expres sions of ventricular diastolic function and cardiac output. In normall y grown fetuses, both peak velocity during early diastole and time vel ocity integral values significantly increased after fetal blood sampli ng from both atrioventricular valves, whereas no significant changes w ere evidenced in the other parameters considered. Gestational age at t he time of the procedure was positively related to the amplitude of th ese changes. In growth-retarded fetuses, fetal blood sampling induced a significant decrease in time velocity integral value from tricuspid valve, suggestive of a fall in right ventricle output. The amplitude o f the decrease was significantly related to the severity of acidosis i n umbilical vein. In conclusion, the cardiac hemodynamic response to f etal 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.