Abstract 17849: Human Fetal Growth Model of Hypoplastic Left Heart Syndrome: Reduced Ventricular Growth Due to Decreased Preload
Introduction: Hypoplastic Left Heart Syndrome (HLHS) is a congenital condition with an under-developed left ventricle (LV) that provides inadequate blood flow postnatally. Predicting LV size at birth using early stage fetal echocardiogram is a clinical challenge critical to the prognosis of HLHS. HLHS can develop during gestation due to altered biomechanical stimuli during fetal growth.
Hypothesis: We hypothesize that decreased preload in utero, from mitral stenosis/atresia, results in reduced LV growth in the fetal heart.
Methods: We developed a novel finite element (FE) model of the human fetal heart in which cardiac myocyte growth rates are a function of end-diastolic strain, which correlates with ventricular filling, to predict organ-level growth; and tested predictions with echocardiographic measurements in normal and hypoplastic fetal hearts. We computed LV filling as the difference between measured end-diastolic volume (EDV) and the mitral inflow; the FE model was made using human fetal geometry at 20wks.
Results: The strain-based fetal growth model with a normal 20wk preload (0.6ml) is able to replicate published measurements of mean LV EDV (0.9 to 8.3 ml; Fig.1) and LV dimensions (long-axis 18 to 35mm; short-axis 9 to 18mm) from mid-gestation to birth to within 10% r.m.s error. Decreasing preload (-25%) to 0.4ml at mid-gestation in the model, which emulates mitral stenosis in utero, a 50% reduction in LV EDV (3.5mL) and a 40% reduction in LV wall volume (2.4mL) is predicted at birth, similar to HLHS patients (Fig.1). In a blinded case study, using echocardiographic data (LV geometry and preload) from a HLHS patient at 30wks as the input, the model predicted a hypoplastic LV at birth, consistent with the patient diagnosis (Fig.1).
Conclusion: The human fetal growth model presented here is a significant step towards the development of a clinical tool that can be used to predict heart size in HLHS, based on LV filling at the end of the second trimester of pregnancy.
Author Disclosures: S. Dewan: None. A. Krishnamurthy: None. R.C. Kerckhoffs: None. H. Sun: None. J.H. Omens: None. V. Nigam: None. A.D. McCulloch: None.
- © 2014 by American Heart Association, Inc.