NEW METHOD FOR MECHANISTIC STUDIES OF CARDIOMYOPLASTY - 3-DIMENSIONALMRI RECONSTRUCTIONS

The imaging modalities used to study the mechanism of cardiomyoplasty, such as echocardiography and radionuclide scintigraphy, are seriously limited by their two-dimensional format. Radiofrequency-pulse-tagged magnetic resonance imaging was used to generate three-dimensional reco nstructions of the left ventricle throughout the cardiac cycle after c ardiomyoplasty. In 2 dogs that had undergone conditioned, right anteri or cardiomyoplasty, wrap stimulation with alternating heartbeats was f ound to produce marked translation of the left ventricle in the short- axis plane, rotation around the long axis, and displacement along the long axis with net long-axis compression; there was no augmentation of radial squeeze. The findings from this study suggest that any systoli c augmentation produced by the right anterior wrap is due primarily to long-axis compression. Our study demonstrates a new, more accurate te chnique of assessing the mechanical effects of cardiomyoplasty in thre e dimensions, thus permitting a more rational optimization of wrap con figurations, and emphasizes the perils of using standard two-dimension al imaging modalities in this setting of exaggerated three-dimensional motion.