Fetal Longitudinal Myocardial Function Assessment by Anatomic M-Mode

Abstract

Aim: To evaluate the feasibility of offline anatomic M-mode (AMM) to study fetal atrioventricular annulus long-axis displacement (LAD) and compare its performance against real-time conventional M-mode (MM). Material and Methods: Paired AMM and MM LAD studies were recorded prospectively in 54 fetuses, and performance was compared. Insonation angles were less than 30° in all but 4 cases. The overall feasibility of AMM was tested in a composite total sample of 91 normal singleton pregnancies (median gestational age 23⁺⁶ weeks, range 12–36). AMM LAD was measured by placement of a virtual M-mode line on digitally stored raw data of fetal 4-chamber video loops. We studied annulus LAD at the lateral mitral (left ventricle; LV), proximal mitral (intraventricular septum; IVS), and lateral tricuspid (right ventricle; RV) myocardial segments. We compared LAD and its regression with gestational age measured using both methods in paired studies and AMM in the whole cohort. Results: Annulus LAD was measured using AMM, in all cases and segments, irrespective of cardiac axis alignment to the ultrasound beam. Good correlation existed between AMM and MM (RV r = 0.901, LV r = 0.899, IVS r = 0.815, p < 0.001). AMM recorded higher LAD values than MM in RV [mean 6.17 (SD 1.46) vs. 5.82 (SD 1.74) mm, p = 0.002] and LV [mean 4.18 (SD 1.11) vs. 3.98 (SD 1.12), p = 0.007]. Both methods showed LAD in RV > LV > IVS and a significant gestational increase in LAD values in all segments (p < 0.001) Conclusions: AMM permits offline evaluation of fetal longitudinal myocardial function in routinely obtained 2D fetal heart images with similar values to conventional MM in paired studies recorded <30°.