胸部外科

The Robot-assisted Cardiac Surgery Council （RACSC） was established in 2015, and consists of the members of three closely related surgical societies and associations. The RACSC conducts the review and approval of applicant surgeons and institutions. A registry system has also been established through the Japan Cardiovascular Surgery Database-National Clinical Database（ JCVSD-NCD）. For the last five years, including the time when robotic mitral valve surgery was first approved as a procedure covered by the Japanese social insurance system in 2018, a total of 1,161 patients were enrolled in the JCVSDNCD, with an increase of nearly 500 cases per year. These cases underwent operations in 25 approved hospitals. The mean patient age was 59±13 years（ range：20-90 years）, and the male to female patient ratio was 1.8 male dominant. The most common procedure was mitral valve reconstruction, and 79％ of all patients underwent annuloplasty. The mean operative time was 238±100 min, the mean cardiopulmonary bypass （CPB） time was 158±69 min, and the mean aortic cross-clamp （AXC） time was 102±49 min. When these results were compared with those of the Cleveland Clinic, which treated more than 1,000 cases as an initial institutional experience, both CPB and AXC times were nearly the same. It is believed that 200 cases are needed to stabilize the CPB and AXC time. Currently in Japan, only 3 or 4 out of the 25 approved hospitals have performed more than 200 cases over the past 5 years. The 30-day hospital mortality and redo operation rate for persisting mitral regurgitation was 0.3％ and 0.6％, respectively, almost equivalent to that of the Cleveland Clinic. We believe that the 5-year result for robotic mitral surgery in Japan is acceptable. It is of note, however, that the length of hospital stay was 10.8±7.6 days, much longer than that of patients at the Cleveland Clinic（ 5.2±2.8 days）, and the homologous blood transfusion rate was 40.3％, twofold higher than that of the Cleveland Clinic（ 20.5％）. Therefore, the full benefits of less invasive robotic mitral repair surgery have not yet been achieved. Further improvements in results are both essential and anticipated.

Endoscopic surgery has been introduced as a minimally invasive procedure in other fields. On the other hand, the introduction of surgical robots has made endoscopic surgery possible in cardiac surgery. Coronary artery bypass surgery includes minimally invasive direct coronary artery bypass（ MIDCAB） via small thoracotomy after robotic internal thoracic artery harvesting and totally endoscopic coronary artery bypass with a robotic anastomosis. We refer to intracardiac surgery performed via only ports as “keyhole cardiac surgery”. Robotic keyhole mitral valve repair is far superior to median sternotomy or minimally invasive cardiac surgery（ MICS）. Currently, the “da Vinci surgical system” is the sole leader in surgical robotics, but there are already many surgical robots, including new concepts. In Japan, the “hinotori surgical robot system” is already on the market, and it is expected that the indications for surgery will expand in the future.

Robot-assisted valve repair refers to an intervention added to conventional minimally invasive cardiac surgery（ MICS）, which is covered by national insurance since April 2018. However, currently, this procedure is performed only at a few hospitals, which is attributable to the need for specialized facilities, as well as surgeon-related criteria including high technical expertise. Notably, the learning curve to stabilize robotic surgery is longer than that for conventional MICS. Our hospital introduced robot-assisted valve repair in June 2018, and we have performed ＞120 surgeries to date. Our policy focuses on “no compromise in the quality of valve repair”. The loop technique is routinely used for valve repair, and the experience gained from median sternotomy and MICS is directly applied to robotic procedures. Robot-assisted surgery enhances surgical field visualization and improves operability even in cases of complex valve repair. In this article, I will describe the procedural innovations, secure establishment of cardiopulmonary bypass, surgical outcomes, and the current challenges in robot-assisted valve repair to achieve safe and improved results.

It has been more than 10 years since the introduction of small-incision surgery for cardiac valvular disease. The so-called minimally invasive cardiac surgery （MICS） techniques avoid the need for sternotomy, but they are still not considered standard approaches. We started performing MICS at our hospital in October 2010, and we started performing robot-assisted cardiac surgery in June 2019 while undergoing a transition from direct vision to complete endoscopic surgery. We performed a total of 81 cardiac procedures between June 2019 and December 2021；78 of these included mitral valve repair. Because robot-assisted cardiac surgery is an extension of MICS, it is essential to establish safe MICS procedures before introducing robot-assisted cardiac surgery to an institution. We will review and report the results of these procedures at our hospital, including MICS and plastic procedures performed as preparation for the introduction of robot-assisted cardiac surgery. We will also describe changes and ingenuity in robot-assisted cardiac surgery procedures after introduction.

Since 2014, we have used the da Vinci surgical system to perform internal thoracic artery harvest in minimally invasive direct coronary artery bypass （MIDCAB）, and since 2016, we have also performed robot-assisted cardiac surgery（ RACS） for mitral and tricuspid valve surgery, left atrial thrombosis, and myxoma, all of which we have had performed as minimally invasive cardiac surgery（ MICS） previously. Even after the introduction, different ideas （Chordalizer, COR-KNOT, special long CP cannula, de-air technique, etc.） were developed. As a result of the learning curve, more stable surgery could be performed. However, keeping in mind that RACS is only a means and not a purpose, the RACS indication should always be carefully considered. When problems, such as intracardiac manipulation or uncontrollable bleeding, occur, safe surgery must be decided to switch to normal thoracotomy as soon as possible. A further enhancement would be expected for even better results and expansion of the RACS indications.

Initial 37 cases of robot-assisted cardiac surgery were reviewed. The early outcomes were favorable with low transfusion rate and no mortality, but some of the very early cases required reoperation after discharge. In our cohort, in terms of aortic cross-clamp time, the learning curve seemed to mature at shortly after the 30th case, but in view of the whole operation time, it did not plateau as of the 37th case.

The trend in cardiac surgery is moving toward minimally invasive procedures worldwide. In Japan, robot-assisted cardiac surgery has started simultaneously with the insurance coverage of minimally invasive cardiac surgery in April 2018. Technology innovations such as the miniaturization of the robot arm, the development of various type of instruments have improved operability and has contributed to the spread of robot-assisted cardiac surgery. On the other hand, there are several issues that may be barriers to its widespread use. The number of facilities for robot-assisted cardiac surgery has not increased as expected probably due to the current insurance system, that is still being developed, the requirement for implementation, and the cost. The current status and issues of robot-assisted cardiac surgery in Japan will be discussed.