Feature

As of January 2016, heart transplantation had been performed in 269 patients in Japan.
Among these, 67 patients had undergone transplantation in our hospital, which is one of the leading institutions for heart transplantation in Japan.
We also perform ventricular assist device surgery proactively in patients with severe heart failure.
In addition, our institution played an important role in the investigator-initiated clinical trial of the pediatric ventricular assist device that was approved in August 2015 in Japan.

Heart transplantation is a surgical transplant procedure for patients with severe heart failure, in which the patient's own heart is removed and replaced with the heart of a brain-dead donor. The procedure can only be carried out when a brain-dead donor has decided in favor of being a donor before finding him/herself in that condition. Therefore, only recipients who meet specific criteria can be candidates for transplantation. Specifically, heart transplantation will only be considered for patients with one of the conditions shown in Fig. 1 that has not been improved by any medical intervention (oral medications and/or drips) or surgical treatment. Patients who wish to be transplant candidates need to register onto the waiting list of the Japan Organ Transplant Network for Transplantation.

The world's first heart transplantation was performed in December 1967. Thirty years later, in October 1997, the "Law on Organ Transplantation" was enacted in Japan. Subsequently, the first heart transplantation after the law’s enactment was performed in February 1999. The law was amended in July 2010. While children under 15 years of age originally could not donate their organs after brain death, that age limit was eliminated when the amendment became effective. In addition, the revised law authorizes the transplant of organs from brain-dead persons whose organ donation wishes are unknown but whose family members agree to the donation. While heart transplantations had only been performed in 69 patients in Japan before the law amendment, the procedure became more frequent afterwards, with 200 patients receiving transplant surgery over five and a half years. In October 2010, the law was additionally revised to indicate that the organ of a donor under 18 years of age should be preferentially transplanted to a child under 18 years of age at the time of his/her registration for transplantation. In February 2013, the age limit for registration on the organ transplantation waiting list was raised to 65 years, allowing for heart transplantation in older patients.

Heart transplantation is currently performed at 9 institutions in Japan. Among these, 4 institutions, including the University of Tokyo Hospital, are allowed to perform heart transplantation in children under 11 years of age. Our hospital was approved for heart transplantation in November 2002. As of January 2016, a total of 67 patients aged from under 10 years up to their 60s had undergone heart transplantation in our hospital, the third-largest record in Japan. Among these, 9 cases were performed before the 2010 law amendment. Afterwards, our division performed heart transplantations in 58 patients, the highest number in Japan. The nine-year post-transplant survival rate of patients undergoing heart transplantation at our hospital is 97%, which is considered high. Patients who may have difficulties finding a compatible donor in Japan due to the limited population of donor candidates – e.g., children – can choose to receive an organ transplant in another country. As of January 2016, 12 patients had undergone transplantation in another country.

As the pool of donors in Japan is limited, a number of patients with heart failure currently stay on the waiting list for transplantation and await their turn for a long time. This is an issue that remains to be solved. Most of the patients on the waiting list are implanted a ventricular assist device (VAD) to help them wait for the transplantation. The VAD supports the weakened heart of patients suffering from systolic dysfunction with a low cardiac output causing reduced systemic circulation due to severe heart failure. There are two types of devices for adults: the external VAD, which is a pump placed outside the body, and the implantable VAD, a device whose components are mostly implantable in the body. A small implantable VAD has recently been approved in Japan, marking an improvement in the quality of life (QOL) of patients. While those who use an external VAD need to stay in the hospital for treatment, implantable VADs are easier to handle, allowing patients to stay at home with their family's support. We perform implantable VAD surgery proactively at our hospital. As of January 2016, a total of 99 patients, including trial cases, had undergone the placement of an implantable device (Fig. 2). Some of the pediatric patients were able to return to school after the implantable VAD surgery. In addition, we also provide medication and rehabilitation programs to help wean patients off their assist device.

The VAD is an important tool for the life sustenance of patients awaiting heart transplantation. While it is increasingly used in the treatment of adult patients, the use of VADs in small children was not available until recently in Japan. In 2011, our institution launched an investigator-initiated clinical trial of a pediatric VAD in cooperation with Osaka University and the National Cerebral and Cardiovascular Center. The pediatric VAD (an external VAD) (Fig. 3) was approved in Japan in August 2015. The trial devices were placed in 9 patients. While some of them have now undergone heart transplantation successfully and others are still using the device, all are currently alive. The mean support period was longer than 280 days, and one of the patients was supported by the device for over two years. This device is the first circulatory support system approved in Japan that can provide support for a period longer than one month. It is expected that the long-term, stable support offered by the device will enable more pediatric patients to undergo heart transplantation in Japan. Moreover, it has been demonstrated that external VADs recover the heart function of 10–20% of adult patients, resulting in weaning off the assist device. Therefore, the use of the pediatric VAD in combination with other treatments, including medication and regenerative medicine, may also be expected to improve the patient's heart function by supporting the blood circulation over the long term.