From the Heart: How a heart transplant works

A heart that is being transported for transplant must be moved quickly and safely

There were 115 heart transplants in the UK in the last year, but why do people need a new heart? And how do they get one?

A patient joins the register of those needing a heart transplant if they have terminal heart failure and a life expectancy of less than 12 months.

Reasons for heart failure include;

  • cardiomyopathy

  • coronary artery disease

  • valvular heart disease

  • re-transplantation (when a transplant has failed or an organ has been rejected)

  • complex congenital heart defects

The longest survival after heart transplantation is 29 years, survival rates have improved dramatically in the last decade.

Donor selection is critical to successful transplant. A patient is selected as donor if they are certified as brain dead - when two separate brain stem function tests show no activity.

An organ donor and a recipient are matched if the following criteria are met:

  • Age (under 45 for men, under 50 for women)

  • A donor's weight must be within 25% of the recipient's weight

  • The donor and recipient must have blood-type compatibility

  • There is no evidence of heart injury in the donor (they have had no ECG)

  • There is no active infection (e.g. HIV or bacterial infection)

  • The donor had no tumours (other than brain)

Once a donor has been identified as a match timing is crucial to the success of the transplant. There is a window of just 4 hours from the moment the donor heart stops beating until it is placed on to perfusion at the transplant hospital.

Helicopters are mainly used for transporting emergency patients and organs, they will only travel by plane if they are travelling more than 2 hours, which is rare.

The retrieval team will go in to where the organ is located. The retrieval team is usually made up of five or six people including;

  • a donor care physiologist

  • a transplant practitioner

  • a scrum nurse

  • One or two surgeons

They then retrieve the heart. Once they have the organ ready it is placed in an ice box and transported back to the transplant hospital.

Once the heart has been brought back it will be transplanted in to the recipient as soon as possible. A heart transplant takes around 3 - 5 hours.

It takes several surgeons to perform an organ transplant Credit: Rui Vieira/PA

During a heart transplant a heart bypass machine keeps blood circulating.

After the operation the patient is kept in a special unit with minimal risk of infection. They are given immunosuppressant drugs to control the rejection of the “foreign” body by reducing the strength of your body’s immune system, which heightens the risk of infection. The immunosuppressant are strong to begin with but are gradually reduced and will be taken for the rest of the patient’s life.

A patient will likely be in hospital for 2-3 weeks following the transplant, when they are discharged they will take part in rehabilitation and have regular check ups.

Sometimes the route a heart takes to make it to a transplant is a little more complicated. A "domino heart" is a heart donated by someone who needs a lung transplant (often cystic fibrosis patients).

Occasionally doctors and surgeons will put these patients on the waiting list for a combined heart and lung transplant and replace both their lungs and heart at the same time.

As their heart is healthy and transplantable, when they go into surgery and have their organs removed to their new receive organs, their heart will go into the donor pool and is transplanted in someone on the waiting list for a healthy heart.