Changes in QRS and T-wave Loops Subsequent to an Increase in Left Ventricle Globularity as in Intrauterine Growth Restriction: a Simulation Study

Freddy L Bueno-Palomeque1, Konstantinos Mountris2, Ana Minchole3, Nuria Ortigosa4, Esther Pueyo5, Pablo Laguna6
1Universidad de Zaragoza, 2Aragon Institute of Engineering Research, University of Zaragoza, IIS Aragon, 3University of Oxford, 4Universitat Politècnica de València, 5University of Zaragoza, 6Zaragoza University


Intrauterine growth restriction (IUGR) is associated with cardiovascular remodeling, which manifests by more globular ventricles when assessed by the sphericity index (base-to-apex length/basal diameter). These changes, which are more prominent in the left ventricle, have been suggested to lead to higher cardiovascular mortality in adulthood. Previous ECG studies have shown that the angle between QRS and T-wave dominant vectors are able to identify adults with cardiovascular remodeling subsequent to IUGR, but the underlying mechanisms are not yet well understood.

In this study, we perform electrophysiological simulations in a human biventricular geometry for control and in one with a spherical left ventricle (SLV) built by applying loads onto the control geometry. We include transmural ventricular heterogeneities and a Purkinje network. Cellular electrophysiology is represented by the O’Hara-Rudy model. 12-lead pseudo-ECG are calculated, from which dominant QRS and T-wave angles are computed. The sphericity index for the control model is 1.54, while for the SLV model it is 1.22.

The angle between the dominant vector of QRS loop and of the T-wave both projected onto XY plane, ΦR−XY − ΦT−XY, is lower for SLV model, as previously observed in IUGR adults (see Table). The angles of the QRS loop in the three planes, ΦR−XZ, ΦR−XY, and ΦR−YZ, are larger for SLV model, concordant with IUGR data for planes XZ and YZ. Other results in IUGR adults could not be reproduced in our simulations. Our findings suggest that a more globular left ventricular shape leads to changes in the angles of QRS and T-wave loops. These changes are concordant between simulation and IUGR data for the angle in the XY-plane, ΦR−XY − ΦT−XY, reported to be significantly reduced in IUGR adults.