1. Department of Cardiology, Kitamurayama Municipal Hospital, Higashine, Japan
2. Department of Cardiology, Nihonkai General Hospital, Sakata, Japan
3. Department of Neurosurgery, Nihonkai General Hospital, Sakata, Japan
4. Department of Cardiology, Pulmonology, and Nephrology, Yamagata University School of Medicine, Yamagata, Japan