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.