[MINIMALLY INVASIVE CARDIAC SURGERY IN JAPAN: INTRODUCTION].

Minimally invasive cardiac surgery (MICS), first introduced in the 1990s, was originally performed via partial sternotomy, the subxyphoid approach, and right anterolateral thoracotomy. Over the past 20 years, MICS procedures have progressed from mere alternatives to standard full sternotomy to endoscope-assisted and then to totally endoscopic open-heart procedures. MICS has gained popularity among surgeons and patients; without sacrificing the safety level and durability of cardiac procedures equivalent to median sternotomy, refinement of MICS technologies has resulted in a decrease in length of hospital stay, less postoperative pain, faster patient recovery, and faster return to activities of normal daily living. Such refinements were achieved not only by the tireless efforts of surgical pioneers but also by the introduction of surgical instruments and endoscopic technologies as well as various, techniques for peripheral cardiopulmonary bypass. On the other hand, an increase in the number of interventions in structural heart diseases such as transcatheter aortic valve implantation, MitraClip percutaneous mitral valve repair therapy, and closure of atrial septal defect is a motivation for further improvement of MICS technologies to enhance safety, durability, and reproducibility.