[1] Asahikawa Med Univ, Dept Cardiac Surg, 2-1-1-1 Midorigaoka Higashi, Asahikawa, Hokkaido 0788510, Japan
[2] Engaru Kosei Hosp, Dept Cardiol, Engaru, Japan
[3] Engaru Kosei Hosp, Dept Radiol, Engaru, Japan
[4] Asahikawa Med Univ, Dept Anaesthesiol, Asahikawa, Hokkaido, Japan