[1] Keio Univ, Sch Med, Tokyo, Japan
[2] Univ Tokyo, Tokyo, Japan
[3] Showa Univ, Sch Med, Tokyo 142, Japan
[4] Juntendo Univ, Sch Med, Tokyo 113, Japan
[5] Tokyo Metropolitan Geriatr Hosp, Tokyo 173, Japan
[6] Musashino Red Cross Hosp, Tokyo, Japan
[7] Surugadai Nihon Univ Hosp, Tokyo, Japan
[8] Nippon Med Sch, Tokyo 113, Japan
[9] Sakakibara Heart Inst, Tokyo, Japan