Spatial distribution measurement of heart wall motion generated by remote perturbation of inner pressure

This study proposes a novel method to noninvasively perturb the left ventricular (LV) internal pressure by remotely actuating the brachium artery with the sinusoidal vibration for diagnosis of the myocardial movability. By attaching an actuator to the brachium artery and driving it by sinusoidal wave of f₀ Hz, the inner pressure of the artery is perturbed. The perturbation propagates along the artery to the LV of the heart and the perturbation of the LV inner pressure is generated. Using ultrasound-based method, the resultant minute motion on the heart wall can be measured. Since the vibration mode of the heart wall depend on the actuated frequency, the vibration mode and the positions of the nodes can be identified from the measurement of the spatial distribution of the heart wall motions by scanning the ultrasonic beam. Finally, from the resultant strain and the delay of the strain to the applied pressure, the instantaneous myocardial movability and its transition property during one cardiac cycle are noninvasively estimated. By the phantom experiments using a spherical shell made of silicone rubber was set in a water tank with a silicone rubber tube and in vivo experiment, the principle was confirmed. By measuring the spatial distribution of the heart wall motion using ultrasound, the vibration mode is identified, which has a potential to noninvasively evaluate the movability and its transition property during one cardiac cycle.