An asymptomatic case of type B dissection developing type A dissection during transferRunning title: Asymptomatic retrograde type A aortic dissectionKayo Sugiyama1, Hirotaka Watanuki1, Masato Tochii1, Katsuhiko Matsuyama11Department of Cardiac Surgery, Aichi Medical University Hospital, 1-1 Yazako Karimata, Nagakute, Aichi, 480-1195, JapanCorresponding author: Kayo Sugiyama, MD, PhDDepartment of Cardiac Surgery, Aichi Medical University Hospital, 1-1 Yazako Karimata, Nagakute, Aichi, 480-1195, JapanTel: +81-561-62-3311, Fax: +81-561-63-6193E-mail: kayotaro3@gmail.com