1. From the Department of Cardiovascular Medicine, Graduate School of Medicine (T. Shindo, K.T., T.O., K. Hatanaka, R.K., K.E., Y.K., K. Hanawa, K.A., T. Shiroto, S.K., S.M., H.S.) and Department of Electronic Engineering, Graduate School of Engineering and Division of Biomedical Measurements and Diagnostics, Graduate School of Biomedical Engineering (H.T., H.H., H.K.), Tohoku University, Sendai, Japan.