Heart transplants - where do we go from here? Mr André Simon, director of heart and lung transplantation and ventricular assist devices, on the future of heart transplants and the life-saving work of Harefield Hospital. I was 18 when I saw my first heart transplant. It was 1986 and I watched in amazement as two surgeons tied knots so fast you couldn't see their fingers. Both my parents were doctors, my father, Dr Ruediger Simon, was a cardiologist so I had an early insight into the field. Then as a student I had the opportunity to come over to the UK from Germany and train at Harefield and Royal Brompton hospitals in 1992 and 1993, so I got to learn from Professor Sir Magdi Yacoub himself. Sir Magdi achieved an enormous amount, and I am extremely proud that I succeeded him. I remember thinking at the time what a cool job he had, so I was very pleased to get this position, working within the NHS. Of course, things have changed a lot since I started my training in the late 1980s. Better outcomes, greater demand For heart transplant patients, data from the International Society of Heart and Lung Transplantation shows that 84.5 per cent live of patients live for a year or longer following their operation, with 72.5 per cent still alive after five years. It’s a significant improvement compared to the 1980s, where the figures were about 76.9 per cent and 62.7 per cent respectively. Overall, we are in a much better position because we can do things we couldn't do – but you could also argue that we, the medical profession, have also lost some of the necessary drive to push limits. Another obstacle is, of course, that the number of donor organs – about 200 per year in the UK – is a lot fewer than needed. In 2008, 95 people were waiting for a new heart, but there were 127 donations. Compare that to 2017 when 249 people were waiting, with 199 donations. This is because we are now able to transplant patients who, just ten years ago, would have been considered too sick for the procedure. What are the solutions? There are ongoing experiments using stem cells to grow new heart tissue that is disease-free, and other avenues such as xenotransplants – taking organs from other species, namely pigs – have been tried without success. One obvious solution for successful transplant surgery is to give the very best chance to success using the hearts that have been donated. This means ensuring they are in the very best condition when they arrive in the operating theatre. The standard current technique is: once the donor has been declared clinically and legally dead, the heart is stopped and stored in a cool solution while it is transported to the appropriate transplant centre. If this takes longer than three hours, the odds of the heart being viable for transplant decrease rapidly. But if a beating heart is perfused (supplied with) with warm blood, and kept beating with an electrical pulse, it can be preserved for up to 12 hours out of the body – dramatically increasing the recipient’s chances of a successful operation. Since 2013, we have used the organ care system, also known as the ‘heart in a box’ system at Harefield. It simulates the conditions of the human body and pumps oxygenated blood inside the heart so it can continue to function as it would inside a living person. As a result, patients at Harefield have had life-saving heart transplants which otherwise would not have been possible, primarily because we have been able to travel greater distances to retrieve an organ and have been able to transplant many more patients who already have an implanted device – such as a left ventricular assist device (LVAD) – keeping them alive. For us, the organ care system has become the gold standard for organ retrieval – we’ve carried out 144 heart transplants using it, and we use it for every single heart transplant patient. Firstly, it means we can treat more patients. Secondly, it means patients recover more quickly, so spend less time on intensive care, and in hospital, after their transplant. We have also reduced the incidence of post-transplant heart failure. Mechanical devices – a Harefield Hospital success story The left ventricular assist device (VAD) – an artificial pump that helps the left side of the heart when it has lost the ability to pump enough blood – can keep patients alive until they can have a transplant. Around the world, VADs have already become routine clinical practice, and many thousands of patients have been treated. At Harefield Hospital, we implant by far the largest number of VADs in the UK and have many teams from other countries visiting to train with us, both on surgical techniques and how to set up VAD programmes from scratch. In some countries, although not the UK, VADs are now used in many instances for what’s called ‘destination therapy’, substitutes for heart transplants rather than an interim measure. There are many happy stories as the result of our work – people who simply would not be alive without them. In 2015, Chloe Narbonne, then aged 12, received what’s called a total artificial heart, making her the third youngest person in the world to have undergone this procedure. She had suffered from dilated cardiomyopathy, when the heart becomes enlarged and cannot pump blood efficiently around the body from birth. She had already had one heart transplant at another hospital. When this failed, her only option was an artificial heart to act as a ‘bridge’ until another heart became available. Teams from Harefield, Royal Brompton and Great Ormond Street hospitals were all involved. A few weeks later, we replaced the artificial heart with another donated heart at Harefield Hospital. Chloe is now doing well and is back at school. Last year, we also gave 39-year-old patient Selwa Hussain a total artificial heart, as she was too unwell for a transplant. She became the first ever woman in the UK to leave hospital with the device. It’s not a permanent solution and she is waiting for a transplant at the moment. But she is out and about – it means she can spend time with her young children. Without it, Selwa simply would not have survived. Nothing short of miraculous Of course, despite huge advances, engineering has not yet come up with a permanent replacement for the human heart. Let’s put it in context. The human heart beats 70 times per minute – now calculate how many times it has had to beat in an 80-year-old. It cannot fail. So, for a start, you need a very, very dependable device – it has to work relentlessly. The mechanical strain resulting from that and the fact that that it has to create a blood pressure, with every beat, of 120mm of mercury, is enormous. If you do the calculations of the actual forces at work in the human heart valves, and consider how thin and how fine they are, and the pressures they withstand, they are nothing short of miraculous. The problems we face are making a device that does not lead to clotting or stroke, and creating a system that works 100 per cent of the time. If you want to fully implant it with no cable and external batteries, transferring energy to the device inside the body without ever burning the patient’s skin is another challenge. And then make sure all those components can work for, say, 60 years without missing a beat. Developing the Harefield Hospital transplant programme The numbers of people having transplant surgery here has increased significantly in the last eight years. When I first came here they did seven heart transplants a year. Over the past year alone, between April 2017 and March 2018, we have performed 33 heart transplants, 59 lung transplants and five heart and lung transplants. Last year, we implanted five total artificial hearts and 37 ventricular assisted devices. We are also the only centre in the UK which can transplant patients who are currently receiving extra-corporeal membrane oxygenation (ECMO) support. And we have expert staff with the widest range of skills in the country when it comes to using mechanical devices to support patients’ hearts. With our planned partnership with King’s Health Partners, I think we have very good long-term options for treating end stage heart and lung failure. When I started at Harefield Hospital, my vision was to offer high-end medicine, to be competitive with leading institutions around the world, and be at the forefront of getting new valuable technology and pioneering new techniques. I think we’re making good progress. Our Harefield Transplant Appeal supports the world-class team at Harefield by funding Organ Care Systems (OCS) which keep donated hearts viable for up to four times longer than traditional methods. To read more and how you can support the appeal, click here. This story was originally published as part of a series of blogs to celebrate the NHS’ 70th anniversary.