An Integrated and Automated Tool for Quantification of Biomechanics in Fetal and Neonatal Echocardiography

ObjectivesTo show simultaneous quantification of flow and mechanics of cardiac function from fetal and neonatal echocardiograms using an integrated set of automated, physics-based, echocardiography analysis methods. BackgroundQuantifying ventricular biomechanics from fetal and neonatal echocardiograms presents unique and significant challenges. Existing analysis tools are designed for adults and cannot accurately assess fetal subjects. MethodsWe used in-house developed analysis algorithms to quantify ventricular biomechanics from four-chamber B-mode and color Doppler routine examinations recordings for three hypoplastic left heart (HLHS) patients at 33-weeks gestation and first week post-birth along with age-matched controls. Chamber morphology, tissue motion, atrioventricular valve inflow, global longitudinal strain, and hemodynamic flow parameters were measured. ResultsPrenatal cardiac output differed between control (LV:157 {+/-} 139 mL/min, RV:257 {+/-} 218 mL/min) and HLHS subjects (410 {+/-} 128 mL/min). This difference persisted for control (LV:233 {+/-} 74 mL/min, RV:242 {+/-} 140 mL/min) and HLHS subjects (637 {+/-} 298 mL/min) after birth. Peak global longitudinal strain measurements did not differ in utero between control (LV: 12.2 {+/-} 4.1%, RV:12.1 {+/-} 4.9%) and HLHS subjects (RV:12.7{+/-} 4.2%). After birth, myocardial contraction increased for the control (LV:15.4 {+/-} 2.8%, RV:22.9 {+/-} 6.9%) and HLHS subjects (14.4 {+/-} 6.2%). Postnatal early filling mitral flow velocity for the control subjects (LV:58.8 {+/-} 17.6 cm/s) and early-filling tricuspid flow of the HLHS subjects (64.8 {+/-} 23.7cm/s) were similar, while the late filling velocity decreased for the control subject LV (33.5 {+/-} 8.1 cm/s) compared to the HLHS subjects (66.9 {+/-} 23.0 cm/s). Importantly, flow energy loss in the fetal HLHS hearts was increased (0.35 {+/-} 0.19 m3/s2) compared to the control subjects (LV:0.09 {+/-} 0.07 m3/s2, RV:0.17 {+/-} 0.12 m3/s2), and further increased postnatally for the HLHS subjects (0.55 {+/-} 0.24 m3/s2) compared to the control subjects (LV:0.23 {+/-} 0.20 m3/s2, RV:0.09 {+/-} 0.06 m3/s2). ConclusionsWe demonstrate the feasibility of integrated quantitative measurements of fetal and neonatal ventricular hemodynamics and biomechanics using only four-chamber B-mode and color Doppler recordings. Short AbstractWe integrated novel echocardiogram analysis methods to quantify ventricular flow and mechanics using apical long-axis B-mode and color Doppler imaging from fetal and neonatal subjects. Three hypoplastic left heart patients (HLHS) imaged at 33-weeks gestation and again in the first postnatal week, along with age-matched controls, were evaluated. For the first time, we show quantified hemodynamics from fetal echocardiography using flow reconstruction, flow energy loss, and intraventricular pressure, as well as global strain and strain rate. These tools are capable of longitudinal analysis of ventricle maturation, flow dynamics, and quantified measurements from routine examinations of complex congenital heart disease.