Understanding Heart Transplants

Anatomy of the human heart
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Heart transplantation is the gold standard treatment for patients with advanced heart failure—meaning no treatment is better. But it’s not perfect. Physicians who care for these patients are constantly looking for ways to improve treatment.

The good news is that more people who need a heart transplant are getting one—for many years, only 2,000 to 2,500 patients a year received a new heart. In 2015, that number rose to 2,804.

In 2016, it rose again to 3,191.

Unfortunately, not enough healthy hearts are donated to ensure that everyone who needs a new heart receives one. Doctors are looking into ways to reimagine the organ allocation system so that those at highest risk are transplanted first.

Why Someone Needs a Heart Transplant

An estimated 5.7 million people in the U.S suffer from heart failure. This means that their hearts can’t pump as strongly as they should, usually due to damage from heart attack, high blood pressure, diabetes, a deformed valve, or a heart disease called cardiomyopathy. These people experience symptoms that may include extreme shortness of breath, fatigue, excess fluid accumulation in the legs and ankles, and trouble breathing when lying down.

Heart failure patients need medications to help their hearts contract more strongly, eliminate excess fluid, and increase blood flow. These medications can slow the progression of heart failure, keep them out of the hospital, and prevent them from dying.

But over time, the medications may stop working. At this point, a heart transplant may be the only option.

Who Should Get a Heart Transplant

The guidelines for who qualifies for a heart transplant and who does not are vague. Each transplant center decides for itself which patients they will take.

Pulmonary hypertension is one of the only medical conditions that disqualifies a patient from heart transplantation.

Furthermore, most centers will not transplant a heart in a patient who is unlikely to take the medications they need after surgery to prevent their new heart from being rejected. Most centers also require candidates to be free of drugs and alcohol for two years before a heart transplant, as well as smoke-free for a period.

There is no age cutoff for heart transplantation, but:

  • Half of patients who receive a new heart are ages 50 to 64. People in this age group tend to do well and can expect to live 10 to 11 years after because they take their anti-rejection medications.
  • Adults over age 70 are at higher risk, because they are likely to have other medical conditions.
  • Patients in their late teens and early 20s tend to be risk-takers and often stop taking their anti-rejection medication. When they do, the results can be disastrous.
  • Babies who need a heart transplant tend to do well since their immune system is under development and parents make sure they take their medications.

Preventing Rejection

Anti-rejection medications depress the immune system, so the body does not view the new heart as a foreign body and attack it. For years, cyclosporine was used to prevent rejection. Today, 90 percent of patients use tacrolimus.

Because tacrolimus is stronger and more potent, less is needed to prevent rejection which also reduces side effects. However, patients who are less likely to reject a donor heart—those who are older, male, and/or caucasian—often do better with the weaker drug.

Substituting a Mechanical Pump

With not enough donor hearts to go around, using a mechanical pump as a permanent heart replacement is under discussion. Ventricular assist devices (VADs) and total artificial hearts are often used temporarily to help a failing heart while the patient is waiting for a transplant (“bridge to transplant”).

Every patient with one of these devices is entered in the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS).

Over time, the information gathered in this database will help physicians determine whether artificial devices could be a safe and effective alternative to a human heart.

Organ Donation

Where you live affects your chances of receiving a new heart or dying before a heart is found. The death rate while waiting for transplantation varies by state from three percent to 22 percent. Patients who live far away from the nearest heart transplant center are less likely to receive a heart than those who live closer. But this is not the whole story.

Currently, waiting patients are placed in broad categories and distinguished by blood type, size, and age. There is growing interest in identifying the factors that put a patient at increased risk of dying before they can receive a heart. This would allow available hearts to go to the sickest patients first, no matter where they live.

Nevertheless, the need for hearts from healthy, younger donors continues to outstrip supply. You can help by registering to become an organ donor here and checking the box on your driver’s license. Even if you are too old to donate a heart at the time of your death, your eyes, skin, or other organs may benefit one or more people.

Dr. Hsich is a cardiologist specializing in heart transplantation. She is Associate Medical Director at Cleveland Clinic's Heart Transplant Program, and Director of the Women's Heart Failure clinic.

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