1. Department of Clinical Engineering , Hanwa Memorial Hospital , 7-11-11 Karita, Sumiyoshi-ku, Osaka 558-0011 , Japan
2. Cardiovascular Center , Hanwa Memorial Hospital , 7-11-11 Karita, Sumiyoshi-ku, Osaka 558-0011 , Japan
3. Department of Medical Engineering , Aino University , 4-5-4 Higashiohda, Ibaraki, Osaka 567-0012 , Japan
4. Graduate School of Applied Informatics , University of Hyogo , 7-1-28 Minatojima-Minamimachi, Chuo-ku, Kobe , Hyogo 650-0047 , Japan