Overview of Heart Transplantation
When someone has severe heart failure, their heart isn’t strong enough to keep the blood circulating in the body, necessitating medical intervention. In severe cases, physicians can suggest a mechanical device that helps the heart pump blood or a drug therapy that helps the heart contract better, but these don’t always improve the patient’s condition over the long term. For some of these patients, a heart transplant can be the best treatment option.
The idea of replacing a failing heart with a healthy one from a donor isn’t new – the first attempted heart transplant happened in 1967. Unfortunately, that patient passed away from an infection 17 days after the procedure. But heart transplants have come a long way since then. Thanks to better drugs that help the body accept the new heart (called immunosuppressants), and improved surgical techniques, heart transplants have become more successful and more common.
In fact, the number of heart transplants performed worldwide grew a lot during the 1990s and early 2000s, and it’s still growing today. However, there are more people who need a new heart than there are donated hearts available. That’s why there are strict guidelines from various medical associations about who is eligible for a heart transplant.
When performed successfully, a heart transplant can greatly improve the quality of life and longevity for someone with advanced heart failure. But like any major surgery, it can come with complications like infection or problems related to the immunosuppressants. Despite these risks, for many people with serious heart failure, a transplant offers the best hope for a longer and healthier life.
Anatomy and Physiology of Heart Transplantation
To understand a heart transplant procedure, you should know about the heart and the major blood vessels located in the center of your chest, an area known as the mediastinum. In history, there are two main types of heart transplant procedures:
1. The Orthotopic heart transplant. In this procedure, the surgeon removes the patient’s heart and places the donor’s heart in the patient’s chest.
2. The Heterotropic heart transplant. Here, the surgeon does not remove the patient’s heart. Instead, they implant the donor’s heart into the patient’s chest alongside the existing heart.
Why do People Need Heart Transplantation
Understanding when a heart transplant is needed is crucial to ensure patients are put on the transplant list at the right time. This can save a patient’s life when they’re relying on heart-strengthening medication or mechanical support until a donor heart is available. Before adding a patient to the transplant list, it’s important to check that they don’t have any conditions that would make a heart transplant risky or harmful.
Chronic Heart Failure
When dealing with heart failure that has been present for a long time (chronic), certain patients should be considered for a heart transplant:
* Patients given standard heart medication who still feel tired and short of breath when they exert themselves (known as New York Heart Association class 3 or 4 or American College of Cardiology stage D).
* Individuals who frequently need to be admitted to the hospital because their heart failure is getting worse despite taking heart medication (two or more times in 12 months).
* Patients whose kidney function is getting worse because of a complication of heart failure known as the cardiorenal syndrome.
* Patients who can’t use standard heart medication due to severe side effects, like low blood pressure or kidney failure.
* Patients whose right chamber of the heart is failing (cor pulmonale) or their lung artery pressure is increasing due to left heart failure.
* Individuals who often experience abnormal heart rhythms that don’t improve with the best medication and therapy.
Other signs, like anemia, weight loss, low sodium levels, or liver problems linked to heart failure can also be reasons to consider a heart transplant.
Acute Heart Failure
In situations where a patient’s heart failure quickly becomes severe (acute), the following cases might require an urgent heart transplant:
* Patients whose hearts can’t pump enough blood to meet their body’s needs (Refractory cardiogenic shock) despite receiving the highest dose of medication.
* Patients who are still in cardiogenic shock even with a device that helps their heart pump blood.
* Patients with fluid build-up in the lungs (refractory pulmonary edema) who are not responding to water pills and need a breathing machine and positive pressure in the lungs.
* Patients with serious and untreatable abnormal heart rhythms.
When a Person Should Avoid Heart Transplantation
Sometimes, people with severe heart failure who need a heart transplant are not able to have one because of certain health problems. These problems include the following:
- Active infections: If you have an infection that is currently affecting your body, doctors would need to treat that before they could consider a heart transplant. However, if you have a chronic infection, like HIV, or hepatitis C or B, that is under control with undetectable levels and no damage to your organs, you could still be considered for a transplant.
- Chronic liver disease, also known as cirrhosis.
- Advanced kidney disease: This is when your kidneys aren’t working as well as they should, and the amount of blood they can clean in a minute is less than it should be.
- Recent stroke or an untreated condition called peripheral vascular disease, which affects the blood vessels outside your heart and brain.
- Uncontrolled diabetes that has caused damage to your organs.
- Active cancer: Doctors treating your cancer would need to be involved in deciding whether a heart transplant could be an option for you.
Also, some people with particular lung problems may not be able to have a heart transplant. These lung problems can include serious conditions that limit your lung function and make it hard for you to breathe out completely or complications from pulmonary embolism, a blood clot in your lung that needed treatment to thin your blood, in the last 3 to 6 months. If you have severe pulmonary hypertension, high blood pressure in the lungs that can’t be controlled with medication, it would also rule out a heart transplant.
There are also some other factors that they would consider, including a lack of social support, severe mental illness, a history of not following doctor’s orders, smoking or drug use (unless you’re willing to quit), extreme overweight, and diseases affecting multiple body systems that would require more than one type of organ transplant.
Equipment used for Heart Transplantation
For a heart transplant to be successful, two main things are required. One is a healthy heart from a donor and the other is a patient who is suitable for the operation. During the operation, a machine called a cardiopulmonary bypass is used. This machine takes over the job of the heart and lungs to keep blood and oxygen moving throughout the body.
A variety of surgical tools are also necessary to carry out the operation. This includes surgical blades and a saw, which the doctor uses to open and cut through the chest. Clamps are used to keep things open while the doctor is working. Cannulas, which are thin tubes, are used to connect with the major blood vessels. And finally, sutures, which are special kinds of stitches, are used to connect the new heart and to close the chest after the surgery.
Who is needed to perform Heart Transplantation?
Heart transplantation is a complex procedure that uses a team of specialized doctors and healthcare professionals. The main doctor involved is a cardiothoracic surgeon, who is assisted by other surgeons. A cardiothoracic surgeon specializes in operating on the heart and chest. They work closely with a cardiac anesthesiologist, who is responsible for making sure you are asleep and pain-free during the surgery.
For a successful heart transplant, a hospital needs to have a dedicated team that includes not only the surgeon and anesthesiologist, but also cardiologists (heart doctors), perfusionists (healthcare professionals who operate the heart-lung machine), nurses, and staff members in charge of coordinating the organ transplant. All of them should have access to a well-equipped operating room and an intensive care unit for closely monitoring patients after the surgery.
This team works together to ensure the best possible outcome for the patient undergoing a heart transplant.
Preparing for Heart Transplantation
When a heart that could be a good match for a transplant is found, the patient, who has not eaten and is clean-shaven, is prepared for surgery. This preparation is planned to match the availability of the donated heart. It’s all coordinated with a special service called the transplant registry, who are responsible for ensuring the heart is a good match.
It’s important to note that the patient is not put to sleep with general anesthetic until we are sure the donated heart can be used. Once that is confirmed, the patient’s existing heart can be taken out. This needs to happen before the donor’s heart arrives to minimize the time the heart is without blood supply, a period known as ischemia.
Once the chest is opened, the doctors get the heart and surrounding areas ready for the next step, which is hooking the patient up to a machine that will do the job of the heart and lungs during surgery, known as a cardiopulmonary bypass. The timing of getting the donor’s heart is very important to minimize ischemia time.
The entire surgery is done under general anesthesia, using lots of monitoring techniques to keep a close eye on the patient. One of these is a tool called a Swan-Ganz catheter, which helps doctors monitor heart’s functioning. Another is a method called transesophageal echocardiography, a special type of ultrasound that lets doctors see images of the heart to ensure things are going as planned.
How is Heart Transplantation performed
There are two types of procedures for transplanting a new heart into a patient: Orthotopic Heart Transplantation, which is common, and Heterotopic Heart Transplantation, which is rare.
Orthotopic Heart Transplantation
In this common procedure, the patient’s own heart is mostly removed, leaving behind certain parts known as “atria”. The donor’s heart is then connected, or “anastomosed”, to the patient’s right and left atria, aorta (a major blood vessel), and pulmonary artery (a vessel carrying blood from the heart to the lungs). This is later followed by a technical step whereby the patient’s right atrium is fully removed and connected to the donor’s right atrium.
Heterotopic Heart Transplantation
This is a much rarer procedure, and the patient’s heart isn’t fully removed. The donor heart is instead added into the patient’s chest cavity. Similar connections, or “anastomoses”, are made between the donor and recipient hearts. Essentially, the patient ends up with two hearts.
Let’s look into the details of the common Orthotopic Heart Transplantation:
Patient’s Heart Removal
This step starts with the surgical opening of the chest. The surgeon then carefully separates the heart’s attached blood vessels and anchors them with tapes. A blood thinner known as heparin is given. Next, tubes known as cannulas are inserted into certain veins and the aorta once appropriate blood clotting time has been achieved.
As the donor heart gets closer to the hospital, the surgical team initiates a heart-lung bypass machine at a low temperature to substitute the heart’s function. Some parts of the heart are then cut and removed, leaving behind particular structures and lengths of the blood vessels which will help in the transplantation of the new heart.
The Donor’s Heart
On the donor’s side, the procedure begins with joining the donor’s pulmonary veins and trimming its left atrium to match the patient’s. It’s also important to inspect the heart valve and check a hole known as the “foramen ovale”. The large blood vessels are also cut to a certain length.
Reperfusion and Completion
Next, the clamps are removed from the vessels, allowing blood to flow through the new heart. The heart gets at least 30 minutes to adjust to this new flow of blood while the body is gently warmed back to normal temperature. It’s also crucial to remove any trapped air in the heart. The patient is then gradually removed from the bypass machine.
At the end of the procedure, drains are placed in the chest to remove any excess fluids or blood. A drug is given to reverse the effect of the blood thinner. The chest is then closed in the usual manner.
Postoperative care and instructions are given to minimize the risk of wound infections. Normally, patients are required to revisit the cardiothoracic surgeon after four to six weeks, for removal of sutures and drains.
Possible Complications of Heart Transplantation
After receiving a heart or lung transplant, a person can experience problems right away or later down the line.
In the days following the procedure, there might be early complications like Primary Graft Dysfunction, where the transplant doesn’t work as it should in the first 24 hours. There’s no apparent cause from surgical issues, rejection, or high blood pressure in the lungs. This happens about a third of the time and can affect the chances of a person surviving up to a year.
Another early complication is rejection of the new heart or lung, where the body’s defense system sees it as a threat and tries to fight it off. This can vary from mild enough not to affect the transplant’s function to severe enough to cause life-threatening problems. A person is checked for signs of rejection through biopsies, with around ten to twelve done in the first year after the transplant.
Infections could also happen, as the medication that keeps the body from rejecting the transplant can also make it easier to get sick. The chance of dying from an infection is highest in the first year following the transplant, which is why it’s important for patients to get shots for influenza and pneumococcal diseases. Patients are also typically given preventative treatment for Pneumocystis jerovecii, cytomegalovirus, candida, and sometimes, herpes infections.
Months or years after the transplant, there could be delayed complications. An example is Cardiac Allograft Vasculopathy where the arteries of the new heart can get narrowed or blocked. This can lead to death and becomes more likely the longer a person has had the transplant. Some patients may have no symptoms of this condition, and it is only detectable during routine biopsies. Medications like statins and rapamycin can delay its development when given early after the transplant.
Approximately 10% of patients experience the onset of new solid tumors, or malignant cancers, one to five years after the transplant. The most common type of cancer is the one associated with the human papillomavirus (HPV), which is a skin cancer. Protection from the sun is recommended for these patients. Lymphoma related to Epstein-Barr virus (a type of herpes virus) is also common in these patients due to the same immunosuppressive drugs used to prevent organ rejection. Other side effects related to these drugs may include kidney disease, diabetes, high cholesterol, and imbalances in blood sugar levels.
What Else Should I Know About Heart Transplantation?
A heart transplant is a complex procedure where a damaged or failing heart is replaced with a healthier one from a donor. The demand for this operation is growing much faster than the number of available donor organs. This means many people are waiting for a suitable heart to become available.
There are several important steps that doctors and health professionals can take to help improve a patient’s chances of receiving a heart transplant and having successful results. First, doctors need to correctly choose who should receive a transplant. This decision is based on their overall health, the severity of their heart disease and other individual needs.
Second, advancements in how donor hearts are stored and transported (organ preservation techniques) can help ensure the heart stays healthy until it can be transplanted. Also, doctors should quickly refer eligible patients for a transplant. This can reduce the wait time for the surgery and improves the chances of success.
Lastly, after the transplant, the patient needs to be carefully monitored for any complications, and they will need to take medications to suppress their immune system (immunosuppression). These medicines help prevent the patient’s body from rejecting the new organ.
By carefully managing these factors, it is possible to enhance the treatment results and the survival rate after a heart transplant.
