A piggyback heart transplant is a surgical technique, also called a heterotopic heart transplant, where a donor heart is connected to the patient’s own heart without removing the original. It works by plumbing the two hearts in parallel so the donor heart helps pump blood while the native heart rests or recovers, a strategy used when a standard replacement would be too risky. Most transplants are not done this way, but piggyback surgery can be lifesaving in select cases.
What is a piggyback heart transplant?
A piggyback heart transplant, formally a heterotopic heart transplant, leaves the recipient’s heart in place and adds the donor heart alongside it. This differs from an orthotopic heart transplant, the standard operation, in which the failing native heart is removed and replaced by the donor heart.
In a piggyback procedure, the native heart stays in, and the donor heart is connected so the two hearts share the work of circulation.
Heterotopic transplants were explored more often before modern mechanical pumps became widely available. Registry data from the International Society for Heart and Lung Transplantation indicate they now represent well under 1 percent of heart transplants worldwide.
How does a piggyback heart transplant work?
Surgeons connect the donor heart to the recipient’s circulation so the two hearts pump in parallel. While techniques vary, the common connections are:
- Left atrium to left atrium, allowing oxygenated blood to enter both hearts
- Donor aorta to recipient aorta, so both hearts can deliver blood systemwide
- Pulmonary artery connections that let the donor heart help move blood to the lungs
Because the hearts have separate electrical systems, they may beat at different rates. Clinicians can sometimes detect dual electrical activity on the electrocardiogram, and the physical exam may reveal complex pulse findings. Teams often use pacing or medications to optimize how the two hearts work together.
Two hearts in parallel raise total cardiac output, which can stabilize circulation when the native heart is too weak or the donor heart alone would be at risk.
When do doctors use a piggyback heart transplant?
The approach is reserved for specific situations where an orthotopic transplant could fail or be unsafe, for example:
- Fixed pulmonary hypertension, which can overload a single donor right ventricle
- Uncertain recovery of severe cardiomyopathy, where the native heart might regain function if given time
- Donor–recipient size mismatch or marginal hemodynamics where parallel support is advantageous
Many scenarios that once favored heterotopic transplantation are now managed with a left ventricular assist device or other durable mechanical support as a bridge to transplant or as destination therapy.
What are the risks and limitations?
- Thromboembolism: Blood clots can form in a poorly contracting native heart and lead to stroke or systemic emboli.
- Arrhythmias: Two hearts can generate competing rhythms, which may cause palpitations or hemodynamic instability.
- Infection and rejection: The patient still needs full immunosuppression to protect the donor heart, with associated risks of serious infection and cancer.
- Complex imaging and follow up: Echocardiography and ECG interpretation are more challenging, and biopsies target the donor heart for rejection monitoring.
Because of higher complexity and complication risk, heterotopic transplants are rare today, largely replaced by orthotopic transplants and mechanical circulatory support.
Why not keep both hearts permanently?
Keeping two hearts long term is usually not desirable once the native heart recovers or when the donor heart is failing:
- Immunosuppression burden: As long as the donor heart remains, powerful anti-rejection drugs are required, which increase risks of infection and post-transplant lymphoproliferative disease.
- Added complication risk: Dual hearts increase the chances of clots and arrhythmias, and future cardiac procedures become more complex.
- No re-donation: A transplanted donor heart is not re-used in another recipient. Once implanted, it cannot be safely or ethically re-donated.
If the native heart demonstrates sustained recovery, surgeons may remove the donor heart to allow reduction or cessation of immunosuppression and to simplify long-term care.
What happened in the Hannah Clark case?
Hannah Clark, treated in the United Kingdom, received a piggyback transplant as a toddler and later developed a rare cancer linked to immunosuppression. In 2006, at Great Ormond Street Hospital, surgeons led by Professor Sir Magdi Yacoub and colleagues removed the donor heart and reconnected her native heart, which had recovered adequate function. Reporting at the time described the outcome as remarkable, and long-term follow up has noted good quality of life (New Scientist), (The Independent), and the Magdi Yacoub Institute.
Her story illustrates a key goal of heterotopic transplantation: give a failing heart the chance to recover, then remove the donor heart if recovery occurs and the balance of risk favors a single, native heart.
How common is it today, and what are the alternatives?
Heterotopic transplantation is now uncommon, with contemporary transplant programs favoring orthotopic replacement in most candidates and using durable mechanical support, such as a left ventricular assist device, when additional help is needed. Current practice patterns and survival trends are summarized in the ISHLT registry reports and clinical overviews like StatPearls on Cardiac Transplantation.