Abstract 3144: Imaging Myocardial Heterogeneity Using Propagation of Pulsive Vibration for Patients with Old Myocardial Infarction
Background: It is well known that the diseased area due to old myocardial infarction (OMI) becomes fibrous. This study shows that a novel method noninvasively visualizes myocardial heterogeneity for patients with OMI.
Method: By a sparse sector scan, the myocardial minute motions were measured simultaneously at about 1,000 points in the heart wall at a high frame rate (> 400 Hz). We have found that a pulsive vibration is excited by aortic-valve closure ( Ultrasound Med Biol 2001; 27: 481). The consecutive spatial distributions of the vibrations clearly reveal that the vibration propagates from the root of the aortic valve to the apex along the heart wall ( IEEE Trans UFFC 2005; 51: 1931). Since its propagation time along the heart wall and the duration period are only several milliseconds and its amplitude is about 100 μm, this phenomenon cannot be measured by conventional equipments. In this study, the method was applied to 7 healthy subjects and 5 patients with OMI, and the spatial distribution of the propagation speed of the vibration is also visualized.
In Vivo Experiments: For all healthy subjects, the propagation of the pulsive vibration was clearly visible both in longitudinal-axis and apical views. Even for the healthy subjects, there is spatial difference in the propagation speed; 4.3 ± 0.5 m/s for the high echo area and 2.9 ± 0.4 m/s for the low echo area, for 60 Hz component in the septum. For all patients with OMI, in the normal region the vibration propagated, but it did not propagate in the diseased area as shown in the consecutive figures at every 4 ms.
Conclusions: These preliminary results indicate that the method has a potential for noninvasively revealing myocardial heterogeneity.