Overview of Heart-Lung Transplantation
Heart and lung transplants have been carried out since the 1980s. The eligibility for these transplants is extremely rare, only suitable for patients in the final stages of both heart and lung failure. Transplant centers often decide not to conduct dual transplants if one of the two organs can be saved or improved. This approach benefits the patient as it lowers the risk of undergoing two transplants at once, shortens the waiting time for a donor organ, and allows more organs to be available for more patients.
Today, most patients are considered for either a lung transplant or treatments for severe heart failure. This can include the use of devices that assist the heart in pumping blood.
In 2014, the United Network for Organ Sharing (UNOS), responsible for organ allocation, updated its policy. It was due to the growing mismatch between organ supply and patient demand, higher death rates among very sick patients waiting for a transplant, and more patients needing a temporary solution while waiting for a transplant. The revised policy created six levels of priority to help classify risks more accurately, largely aiming to reduce death rates among those waiting for a transplant.
The tier system is organized as follows:
Tier 1 consists of patients who are on certain types of support, such as extracorporeal membrane oxygenation, which is a life support machine that does the work for the heart and lungs.
Tier 2 includes patients with specific types of assist devices or those experiencing device malfunction and therefore in poor health.
Tier 3 includes patients who require certain treatments to help their heart work properly or are dealing with complications from devices that support heart function.
Tier 4 is for patients who are on medication, called inotropes, helping the heart pump more strongly, or those who had certain types of heart disease.
Tier 5 covers patients who need multiple organs replaced.
Tier 6 includes all other candidates for a heart transplant.
Even with these advances in organ transplantation and allocation strategies, heart-lung transplants are still uncommon and require a very experienced team. Only about 100 cases take place each year. As heart-lung transplants are so rare, healthcare professionals must stay current with guidelines, allocation policies, and alternative treatments to best serve their patients.
Why do People Need Heart-Lung Transplantation
Heart-lung transplants are complex procedures conducted when both the heart and lungs fail to function optimally. There are usually three reasons why this happens:
1. A heart-related disease eventually leads to failure of the lungs.
2. A lung-related disease ultimately causes the heart to fail.
3. A systemic disease affects both heart and lungs, causing them to fail.
The most common reason for heart-lung transplants (comprises around 35% of cases) involves birth defects in the heart causing conditions called Eisenmenger syndrome and secondary pulmonary arterial hypertension. When the illness reaches the stage where the resistance in the blood vessels of the lungs remains too high even after the usage of drugs to aid the heart function and mechanical circulatory support, the lungs become irreparable. Performing a heart transplant alone in such situations risks causing acute right heart failure.
The secondary most common reasons (around 27% of cases) for heart-lung transplants are diseases causing a high blood pressure that affects the arteries in the lungs and right side of the heart. What constitutes an irreparable right heart varies across different medical centers, especially considering that similar outcomes are achieved by both double lung transplants and heart-lung transplants for these patients. However, most centers would consider a heart-lung transplant if the heart is too large to accommodate a donor lung or the right heart is diseased and hardened.
Patients suffering from a systemic disease such as cystic fibrosis that affects both the heart and lungs, or from lifestyle factors like smoking, which causes both chronic inflammatory lung disease (emphysema) and heart disease, can be considered for a heart and lung transplant. For instance, in cystic fibrosis, the patient’s removed recipient heart could be used as a donor organ for another patient in a process known as a “domino” transplant.
When a Person Should Avoid Heart-Lung Transplantation
When it comes to combined heart and lung transplant surgeries, there are specific conditions that might stop someone from having it, just like there are for separate heart and lung transplants. For instance, currently having or a recent history of having cancer (within the past 2 – 5 years) is a reason one might not be able to have a transplant. People who are dealing with an active substance use disorder, unpredictable mental health disorders, noncompliance with treatment, poor physical condition, or lack of strong social support, might also not be the right candidates for this kind of surgery.
For a potential transplant recipient, blood type incompatibility with the donor, or a test result indicating a strong chance of organ rejection, can also make transplant infeasible. With the time limits set by our current technology for keeping a heart or lung viable outside the body, we can’t always do human leukocyte antigen matching (trying to find a donor whose immune system markers are very similar to the recipient’s). The time limits are usually 4 – 6 hours for hearts and 6 – 10 hours for lungs, at most; obtaining the best results requires reducing these times as much as possible.
In transplant surgeries, if the donor’s lung is significantly larger than the recipient’s lung, it may not be possible to do the transplant. A size difference within 10% above or below the recipient’s weight or height can be managed, but anything more may lead to lung problems like collapsed lung (atelectasis) or a form of water in the lung (hyperexpansion pulmonary edema).
Older age used to be a reason to avoid transplantation, but now we look at individuals’ other health conditions and their age to decide if transplant is possible or not. Similarly, a person having had previous chest surgery used to be considered a risk due to a potential for heavy blood loss during the transplant procedure. However, with surgical advancements and the use of substances to reduce bleeding, this is not a major concern anymore.
Moreover, if someone has a liver condition along with lung disease (for example, if someone’s bilirubin levels are 2.1 mg/dl or greater), careful consideration must be given before doing a transplant. Advanced pulmonary hypertension in these cases often leads to a high risk of death within the first few days after surgery. In these situations, patients might instead be considered for a combined heart-lung-liver transplant.
Preparing for Heart-Lung Transplantation
Before being added to the list for a transplant, those who could possibly receive a transplant must go through a detailed review and evaluation process by a team of healthcare professionals. In the United States, people who need a new heart and lungs are put on the heart transplant waiting list. This is done to take advantage of shorter waiting times. In Europe, however, they use a separate list for those needing both a heart and lungs.
There’s no one-size-fits-all timing for listing someone for transplant. This decision depends on many factors and varies based on the reason why the person’s organ isn’t working properly.
The organization that manages organ donations in the local area should carefully evaluate the person who wants to donate their organs. Donation rules are sometimes updated to help the most people, especially when there is a constant shortage of organ donations. For lung donors, there are now usual and expanded sets of rules.
How is Heart-Lung Transplantation performed
Heart-lung transplants involve three main operations: obtaining the donor organs, removing the recipient’s organs, and implanting the new organs.
Obtaining the Donor Organs
The process for obtaining the heart and lungs from a donor might vary at different medical centers. Typically, the surgeon begins by performing a bronchoscopy, a procedure that allows them to inspect the airways in the lungs. If the airways look healthy, the rest of the process proceeds.
During this process several steps occur. The surgeon makes a cut from the breastbone, inspects all of the anatomy. Medicine is administered, and solution is delivered to the heart and lungs to preserve the organs during the process. Finally, the heart and lungs are removed and packaged safely for transport.
Removing the Recipient’s Organs
The process to remove the recipient’s heart and lungs is complex. The surgeon makes a cut in the middle of the chest, and carefully works around some critical parts of the body. The patient is put on a machine that helps the blood circulate and the body is cooled.
The heart is then removed, followed by the lungs. Once both organs have been removed, the body is prepared for the new donor organs.
Implanting the Donor Organs
The surgeon starts this process by preparing the donor organs. Once ready, the heart and lungs are lowered into the recipient’s chest and kept cold. The surgeon connects the trachea (a tube that carries air to the lungs) first, and then connects the blood vessels. Once all connections are completed, the surgeon checks thoroughly for any bleeding. Finally, the patient’s blood flow is returned to normal, machine support is stopped, and tubes and wires are placed to help with recovery. The patient’s chest is then closed and they are taken to recover in the intensive care unit.
In summary, heart-lung transplants are complex procedures that involves careful extraction and implantation of key organs. The overall goal is to ensure the patient is in the best condition for recovery.
Possible Complications of Heart-Lung Transplantation
Getting a heart-lung transplant is a major operation, and it’s quite normal to have several challenges or complications afterwards. One of the potential issues is a problem with the newly transplanted lung, which could suffer from a lack of blood flow (also known as ischemic reperfusion injury). This can cause abnormal levels of carbon dioxide (hypercapnia) and low levels of oxygen (hypoxia) in your blood and occurs in 15% to 20% of patients two to three days after surgery.
Another worry is primary cardiac graft failure, a serious condition where the new heart doesn’t work properly. This is seen in up to 22% of patients and, unfortunately, can be fatal to about 53% of the time. Patients who have a history of high blood pressure (hypertension) or a condition called sarcoidosis appear to face a higher risk.
We should also mention a potential risk related to breathing issues (acute airway emergencies), though this is reasonably low at 3.8%.
Longer-term problems that may arise after a heart-lung transplant include your body rejecting the new organs. This can cause bronchiolitis obliterans syndrome in the lung (seen in 7% to 31% of patients) and coronary artery vasculopathy in the heart (seen in 8% of patients). Each transplant center has its own ways of watching for these issues, often using a heart ultrasound (echocardiography), bronchoscopy, biopsy, or lung function tests (spirometry).
Also, care is taken to balance immunity and infection because potent immune-suppressing drugs, while helping to keep your body from rejecting the new organs, can increase the risk of infections. Infections can cause a significant proportion of deaths, and fungal infections, in particular, can happen within the first month after surgery.
Side effects from the medications you’ll need to take can also cause problems. For example, high blood pressure (in 88% of patients), high cholesterol (70%), diabetes (17% to 27%), and kidney issues (46%) are common, with a small percent (2% to 4%) progressing to severe kidney diseases requiring dialysis.
Another concern is a higher risk of certain types of cancers, especially a condition called posttransplant lymphoproliferative disorder. This is seen more often in heart-lung transplant patients (7.6%) compared to heart-only (5.4%) or lung-only (3.1%) transplants.
A few more risks include injury or too much handling of the vagus nerves, which can cause stomach problems like gastroparesis, reflux disease, and increased risk of lung infection. Injury to the phrenic nerves may cause difficulties in breathing, while injury to the thoracic duct can lead to a condition called chylothorax, which is a type of lung fluid buildup.
What Else Should I Know About Heart-Lung Transplantation?
Heart-lung transplants, a medical procedure where a patient receives a new heart and lungs, have come a long way since the first successful operation in 1981. Since then, close to 4000 patients have been treated. What’s great is that with enhancements in figuring out who needs this surgery and how it’s done, the survival rate for patients after the operation has been steadily increasing over the years. It has gone up from 2.1 years in 1982-1993, to 3.7 years in 1994-2003, to 5.8 years in 2004-2016.
For those who successfully get through the first year after the operation, they can expect to live an average of 10.3 more years. In fact, a hospital that does a lot of these surgeries reported survival rates of 82% after 1 year, 69% after 3 years, and 54% after 15 years.
It’s crucial to understand that these numbers are related to patients who are extremely sick, with both their heart and lungs failing — without a transplant, they’re unlikely to survive. A significant portion of these patients are young, below the age of 50. With better care now for kids with inborn heart problems, 75% to 85% make it to adulthood. However, 10% to 20% of them may still need a heart-lung transplant later in life. So, this procedure serves as a vital lifeline, offering additional and quality years of life.
