Objectives:

To propose a biventricular performance index based on the average values of the duration of the cardiac cycle of each of the ventricles, to determine the variable included in the study with the most significant statistical correlation, to establish reference values that allow the work of each ventricle to be identified according to this variable, and to obtain a balanced biventricular output index.

Methodology:

Prospective and cross-sectional study in fetuses of 168 pregnant women, in pregnancies between 16 and 38 weeks without maternal-fetal pathologies. Flow velocity waves were obtained from both atrioventricular valves and the total systole-diastole cycle time was calculated in milliseconds for each valve. Averages, standard deviation, and Z-score were calculated of the systolic-diastolic time for each ventricle and the individual ventricular performance index (VPI) were calculated by dividing the value obtained by the fetal heart rate (FHR). The average value of both was obtained and this, when divided by the heart rate, made it possible to obtain the biventricular performance index (BPI) to establish the correlation between this, the fetal heart rate and gestational age.

Results:

Systolic-diastolic time values in milliseconds for the right ventricle were 420.8 (SD ±28.3) and for the left ventricle 418.8 (SD ±26.3), with no statistically significant differences (p<0.371). The correlation with the FHR was negative for both ventricles: (-0.491 and -0.553; p<0.05). The mean biventricular time was 418.37 ms (±20.59) and the correlation with gestational age was 0.48 (p<0.05); the correlation with FHR was negative, -0.50 (p<0.05).The BPI showed values of 2.8 (extremes 2.4 (P5) and 3.4 (P95)). The correlation between BPI and FHR was 0.78 (p<0.05) and of lesser degree with gestational age (0.27; p<0.05).

Conclusions:

It was demonstrated that the systolic-diastolic times of each ventricle did not differ from each other and were negatively correlated with fetal heart rate. It was shown that it is possible to evaluate the fetal cardiac cycle of each ventricle by means of the ventricular performance index as well as to qualify with the biventricular performance index the combined cardiac output as balanced.

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