Noninvasive measurement of isovolumetric contraction time by Doppler cardiography can be substituted for fetal cardiac contractility: evaluation of a fetal lamb study.

Objective: The objective of this study is to clarify whether the isovolumetric contraction time obtained from Doppler cardiography (Doppler ICT) can be an index substituted for fetal cardiac contractility.

Materials And Methods: In 10 pregnant ewes, fetal hypoxemia was induced by giving a variable mixture of gases. Through experiment, the Doppler ICT, pre-ejection period (PEP), and the maximum first derivative of the left ventricular pressure waveform (Max dp/dt) were simultaneously recorded every 10min. The relationship between both the Doppler ICT and PEP, and the Max dp/dt were analyzed.

Results: A significant negative linear regression was founded between the Doppler ICT and the Max dp/dt. A significant negative linear regression was also shown between PEP and the Max dp/dt. Moreover, the regression of Max dp/dt on ICT had significantly less residual variance than the regression of Max dp/dt on PEP (p=0.0004).

Conclusion: In contrast to PEP, Doppler ICT is a reliable, and non-invasive index which can be substituted for fetal cardiac contractility.