Recently the University of Maryland reported that they had successfully implanted a porcine (pig) heart into a man with advanced heart failure. This news has suggested a new frontier for the treatment of patients with advanced heart disease.

It has been of interest not only to cardiologists and the wider medical community but also to the general public. We thought it would be interesting to review the development and role of heart transplantation in the management of heart disease and wonder when such advances will become possible for patients in Jamaica. Cardiac transplantation involves the replacement of a patients diseased heart with a normal functioning heart from a donor. Unlike liver or kidney transplantation in which the organ can be obtained from a living donor, heart transplantation requires that the donor has died – had brain death in which no brain electrical activity is seen but the circulatory system remains intact. A successful cardiac transplantation is the result of several teams of physicians, nurses, ancillary medical personnel along with an administrative system that can coordinate the retrieval and distribution of organs.

It is interesting to note that the idea of animal to human organ transplantation is not new and in fact many of the early attempts to transplant organs involved animal donors. The era of organ transplantation began in the 1960s. Success at that time was limited by poor surgical techniques and inability to prevent rejection of the transplanted organ. The first “successful” heart transplant was performed in South Africa by Dr Christian Bernard with the patient living for 18 days after surgery. Despite this remarkable achievement, solid organ transplantation did not become commonplace until the development of the immunosuppressant drug, cyclosporine in 1976. This drug was revolutionary in its ability to suppress the immune system and thus rejection of the transplanted organ. With continued improvement in anti-rejection therapy and surgical techniques, solid organ transplantation has become an important part of the armamentarium in treating patients with advanced disease of the heart, liver, kidneys, and lungs.

Why is there a need for heart transplantation?

Heart transplantation is done when a patient with advanced heart disease is found to have an extremely increased risk of dying within a short time frame despite optimum available therapy. The most common indication is advanced heart failure where the patient’s heart is not able to pump enough blood to supply the needs of the body. Patients are often bed bound with intravenous medication to support heart function or implanted with mechanical pumps to take over the work of the heart. Other indications include patients with severe blockages in the arteries supplying blood to the heart for which medications and procedures have not been helpful, patients with uncontrollable heart arrhythmias and patients with congenital heart disease for which there is no surgical remedy. The common underlying issue is severe heart disease for which no further treatment is available and there is a substantial risk for dying in the short term. The only two options for patients like this are mechanical pumps to replace the function of the heart or effectively a new heart, “heart transplantation”. It is important to remember that heart transplantation is not a cure for heart disease, and it does not restore a normal lifespan. It alters what is a terminal disease with high morbidity and a short lifespan and by replacing heart muscle improves patient symptoms, moderately extends longevity but introduces significant clinical problems which must be managed over time.

How successful is heart transplantation?

Success in heart transplantation is usually considered over the short term (survival at one year after operation) and long term. Recently, the expected one-year survival is more that 90 per cent. For patients that survive the first year 50 per cent will die over the subsequent 15 years. While this does not sound very impressive, we must consider this in context, because an average patient diagnosed with heart failure has a five-year mortality of approximately 50 per cent and patients with advanced symptomatic heart failure can have one-year mortalities of more than 30 per cent. In Jamaica, the risk of patients with advanced heart failure dying prematurely is thought to be significantly higher than the quoted figures above. Patients experience symptomatic improvement and an increase in their ability to complete day to day activities within a few months after surgery. It is estimated that 70 per cent of patients who have undergone heart transplantation are able to do normal activities of daily living with little to no symptoms.

What are the common problems seen after transplantation?

Aside from the surgical risk of the operation itself, the key issues with heart transplantation are related to the need for immune suppression. Our bodies are very good at recognising tissue that is not ours and given this all solid organ transplants require suppression of the immune system so that the organ is not rejected. Solid organ transplantation including heart transplantation only became clinically viable when methods of preventing organ rejection were developed. After heart transplantation, the patient is committed to lifelong treatment with drugs that suppression the immune system to prevent organ rejection. Unfortunately, these drugs have side effects which can be particular to the drug being used. These include kidney damage or of immune suppression generally. The latter include the risk of infection and cancer. Despite the current regimens for immune suppression after heart transplantation, there is chronic low-grade immune damage to the transplanted heart particularly to the transplanted coronary arteries. Over time damage to these vessels cause impairment of blood flow to the transplanted heart and failure of the heart. Organ rejection and malignancy are the most important causes of death in patients after heart transplantation.

How does taking hearts from other animal’s help?

Heart transplantation is limited by the availability of suitable hearts. As noted above it requires the death of the donor in a manner in which the heart is left suitable for use, for example, severe head trauma. There is currently a severe shortage of hearts requiring that patients needing transplantation spend months to years awaiting a suitable organ. Unfortunately, patients will die while waiting and many others may spend months being cared for in hospital. This period can be complicated by infections blood clots and along with psychosocial issues. This shortage of organs has raised interest in using animal organs, particularly from pigs and primates. Theoretically, animals could be grown to serve as organ donors and dramatically increase the number of organs available for transplantation. The major issues with using organs from other species, are the increased risk of rejection, the possibility of cross species infection and ethical issues. Genetic manipulation as was done at the University of Maryland can reduce the likelihood of rejection. Raising the pigs in sterile environments can allay some of the fears of cross species infection. The ethical issues in raising animals simply to serve as organs donors are real. However, we currently as a society raise animals to serve as food. The harm to the animals will also have to be balanced against the needs of those who are dying of advanced disease that would benefit from organ transplantation. Despite the excitement that this transplant has generated, it is too early to say how the patient will do in the long term and whether this treatment will be applicable to the many patients who are awaiting organs. It however is an exciting development which may revolutionise the management of advanced heart disease. With continued development in this technique, wider availability of organs and improvement in local health-care infrastructure and value chain, there is reason to be optimistic that in the future, advanced therapeutic techniques like heart transplantation may become a viable option for patients in low and middle-income countries like Jamaica.

Dr Ernest Madu, MD, FACC and Dr Paul Edwards, MD, FACC are consultant cardiologists for Heart Institute of the Caribbean (HIC) and HIC Heart Hospital. HIC is the regional centre of excellence for cardiovascular care in the English-speaking Caribbean and has pioneered a transformation in the way cardiovascular care is delivered in the region. HIC Heart Hospital is registered by the Ministry of Health and Wellness and is the only heart hospital in Jamaica. Correspondence to info@caribbeanheart.com or call 876-906-2107