Abstract
ObjectivesMyocardial function can be evaluated using color-coded tissue velocity imaging (TVI) to analyze the longitudinal myocardial velocity profile, and by expressing the motion of the atrioventricular plane during a cardiac cycle as coordinated events in the cardiac state diagram (CSD). The objective of this study was to establish gestational age specific reference values for fetal TVI measurements and to introduce the CSD as a potential aid in fetal myocardial evaluation.MethodsTVI recordings from 125 healthy fetuses, at 18 to 42 weeks of gestation, were performed with the transducer perpendicular to the apex to provide a four-chamber view. The myocardial velocity data was extracted from the basal segment of septum as well as the left and right ventricular free wall for subsequent offline analysis.ResultsDuring a cardiac cycle the longitudinal peak velocities of septum increased with gestational age, as did the peak velocities of the left and right ventricular free wall, except for the peak velocity of post ejection. The duration of rapid filling and atrial contraction increased during pregnancy while the duration of post ejection decreased. The duration of pre ejection and ventricular ejection did not change significantly with gestational age.ConclusionEvaluating fetal systolic and diastolic performance using TVI together with CSD could contribute to increase the knowledge and understanding of fetal myocardial function and dysfunction. The pre and post ejection phases are the variables most likely to indicate fetuses with abnormal myocardial function.
Highlights
In the progression of fetal hemodynamic adaptation, the assessment of fetal myocardial function could be of crucial importance when evaluating fetuses at risk or suffering from intrauterine hypoxia [1,2]
The study included 125 fetuses, at a gestational age of 18 to 42 weeks, all referred to the Centre of Fetal Medicine at the Karolinska University Hospital Huddinge during 2009–2012
Fetal heart rate decreased from a mean 147 bpm at 18 weeks of gestation to a mean 137 bpm at term (r = 0.401), equivalent to a prolonged duration of a fetal cardiac cycle with about 30 ms throughout gestation. This corresponded to an increase in diastolic duration, as the duration of systole did not vary significantly with gestational age, either during pre ejection or ventricular ejection
Summary
In the progression of fetal hemodynamic adaptation, the assessment of fetal myocardial function could be of crucial importance when evaluating fetuses at risk or suffering from intrauterine hypoxia [1,2]. This has been common knowledge since many years, myocardial performance is typically evaluated by specialists in fetal cardiology, and methods to perform these evaluations are regarded as rather cumbersome and have not been introduced in clinical practice. Color-coded tissue velocity imaging (TVI) offers quantitative measurements of regional myocardial function, and can potentially provide more sensitive and earlier indications of myocardial dysfunction. Velocity can be measured simultaneously in the different myocardial walls during the same cardiac cycle
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