IMAGING ASYNCHRONOUS MECHANICAL ACTIVATION OF THE PACED HEART WITH TAGGED MRI

A method for imaging the rapid temporal-spatial evolution of myocardia l deformations in the paced heart is proposed. High time resolution-ta gged MR images were obtained after stimulation of the myocardium with an MR-compatible pacing system. The images were analyzed to reconstruc t dynamic models of local 3D strains over the entire left ventricle du ring systole. Normal canine hearts were studied in vivo with pacing si tes on the right atrium, left ventricular free wall and right ventricu lar apex. This method clearly resolved local variations in myocardial contraction patterns caused by ventricular pacing. Potential applicati ons are noninvasive determination of electrical conduction abnormaliti es and the evaluation of new pacing therapies.