Assessment of left ventricular filling in normally grown fetuses, growth-restricted fetuses and fetuses of diabetic mothers.

OBJECTIVE

To determine fetal left ventricular diastolic function as expressed by normalized left ventricular filling rate integral as well as conventional indices of transmitral blood flow in appropriate-for-gestational-age (AGA), small-for-gestational-age (SGA) and IDDM (insulin-dependent diabetes mellitus) fetuses during the third trimester of pregnancy.

DESIGN

A cross-sectional study of fetal left ventricular filling using conventional parameters of transmitral blood flow.

SUBJECTS

Twenty-five AGA fetuses (mean 32 weeks), 18 SGA fetuses (mean 32 weeks) and 15 fetuses associated with IDDM (mean 31 weeks).

METHODS

Doppler measurements of mitral inflow velocity were converted to relative cumulative volume flow by integration at sequential time points along the velocity contour, producing a relative filling curve of the ventricle. The area under this curve was calculated to obtain the left ventricular filling rate integral.

RESULTS

The left ventricular filling rate integral (I) for the complete diastole (E + A wave) was not significantly different between AGA and SGA fetuses but significantly lower in the IDDM fetus (p < 0.05) compared with the AGA fetus. Ie (E wave) was significantly lower and Ia (A wave) significantly higher in both SGA fetuses (p < 0.05) and IDDM fetuses (p < 0.01) compared with AGA fetuses.

CONCLUSIONS

There is a delay in left ventricular filling which may reflect changes in myocardial relaxation and possible reduction in passive ventricular filling as a result of chronic hypoxemia in the SGA fetus and altered in utero metabolic environment in the IDDM fetus.