[1] Dokkyo Med Univ, Dept Cardiac & Vasc Surg, 880 Kitakobayashi, Mibu, Tochigi 3210293, Japan
[2] Kanagawa Univ Human Serv, Dept Liberal Arts & Human Dev, Yokosuka, Kanagawa 2388522, Japan
[3] Gunma Prefectural Cardiovasc Ctr, Div Cardiovasc Surg, Gunma, Japan
[4] Maebashi Red Cross Hosp, Dept Cardiovasc Surg, Gunma, Japan
[5] Dokkyo Med Univ, Ctr Res Collaborat & Support, Sch Med, Mibu, Tochigi, Japan