Andy Page

Creating a Murine LV Model for Pregnancy

Throughout pregnancy, the left ventricle (LV) grows by approximately 30%; however, little is known about the time course of this growth, as experimental methods provide windows into the rapid changes occurring. We need to understand this growth because cardiovascular issues are the largest contributor to maternal mortality. Finite element modeling (FEM) would improve our understanding of how the LV changes over the entire time course of pregnancy. Our lab previously recorded murine cardiac ultrasounds throughout pregnancy. We applied selected murine measurements for the LV at systole to an existing FEM of the canine LV, using an elastic coupled trans-iso Mooney Rivlin constitutive model; the material properties were fit until the model and ultrasound were similar at diastole before pregnancy (day-0). We used MATLAB to create a new geometry of the heart for the remaining 4 pregnancy and 5 postpartum time points. The predicted sphericity, volume, wall thickness, diameter, and height were compared to one mouse at both systole and diastole for all 10 time points. The average error between the model and data was <5% for sphericity, volume, wall thickness, and diameter at systole. The model’s height had a 12.13% and a 25.37% error for systole and diastole. The average error at diastole for the other four measurements was: 22.80% for sphericity, 8.45% for volume, 11.87% for wall thickness, and 16.32% for diameter. The model was accurate for systole but inaccurate for diastole; the different metrics showed that this model could be expanded to accurately model cardiac growth during pregnancy.