Intrinsic Myoarchitectural Differences Between the Left and Right Ventricles of Fetal Human Hearts: An Ultrasonic Backscatter Feasibility Study

Objective: Embryologically, cardiac chambers differ in their morphologic and contractile properties from the beginning. We hypothesized that a noninvasive ultrasonic backscatter investigation might illustrate the fundamental differences in myocardial morphologic properties of the 2 ventricles during heart development. The goals of this investigation were to 1) explore the feasibility of measuring the magnitude of cyclic variation of ultrasonic backscatter from the left and right ventricular free walls of fetal hearts; 2) compare measurements of the magnitude of cyclic variation from the left and right sides of the heart; and 3) determine if the observed results are consistent with predictions relating the overall backscatter level and the magnitude of cyclic variation. Methods: Cyclic variation data from the left and right ventricular free walls were generated from analyses of the backscatter from echocardiographic images of 16 structurally normal fetal hearts at mid-gestation. Results: The magnitude of cyclic variation was found to be greater for the left ventricular free wall than for the right ventricular free wall (4.5 ± 1.1 dB vs 2.3 ± 0.9 dB, respectively; mean ± standard deviation; P < .0001, paired t test). Conclusion: Measurements of the cyclic variation of backscatter can be obtained from both the left and right sides of fetal hearts demonstrating a significant difference between the measured magnitude of cyclic variation in the left and right ventricular myocardium. This observation is consistent with predictions relating the overall backscatter level and the magnitude of cyclic variation. The results of this study suggest cyclic variation measurements may offer a useful approach for characterizing intrinsic differences in myocardial properties of the 2 ventricles in assessing fetal heart development.