Analysis of the activation propagation on both ventricles using tagged MRI

MRI tagging created new opportunities for motion analysis within the body. With tagged cardiac MRI, detailed motion analysis has been previously shown; e.g. measurements of local strain of the heart could be obtained easily for normal and pathological hearts. In this study, we calculate the activation times using the local time-strain relationship and compute the propagation velocity of the activation for both chambers of the heart. Here, in this initial analysis, we obtained propagation velocities for four canine hearts paced either at the atrium or right ventricle. The first case provides a condition similar to the normal physiological activation. We show here for the first time an activation propagation speed over the right ventricle in vivo. The overall method provides a unique noninvasive method to examine the underlying electrical activation of the heart, but further studies are needed to establish its true clinical value