Lung transplantation is a treatment option for selected patients with
pulmonary hypertension (PH) when medical therapy is no longer effective.
Lung transplantation has many good points, but also significant drawbacks.
On the positive side, transplantation offers a potential cure for PH
coupled with improved quality of life. On the negative side, lung transplantation
has a shorter survival, on average, compared to other solid organ transplants.
Other potential problems include organ rejection, infections, side
effects of drugs that suppress the immune system, and the need to be
followed closely by a transplant center that may not be close to home.
Some lung transplant patients survive ten years or more with a good
quality of life, however other patients survive only a few months or
less. Even at the best transplant centers, the survival statistics
for lung transplants are lower overall than for kidney, liver or heart
transplants. The current lung transplant survival statistics from the
International Society for Heart and Lung Transplantation Registry show
an overall one year survival of 74 percent and a 5 year survival of
45 percent. Thus, survival is less than 5 years for more than half
of the patients who receive a lung transplant. The major long-term
problem is chronic rejection which results in persistent worsening
function of the transplanted lung(s); this problem occurs earlier and
more commonly in lungs compared to other transplanted organs.
Unfortunately, the timing of lung transplantation cannot be controlled,
even though it is a critical issue for many patients. The majority
of donor lungs are obtained from donors who die from accidental injuries,
making the availability of donor organs unpredictable. Many more patients
are waiting for transplants than there are donor lungs available, and
lungs are transplanted according to the length of time a patient has
waited. In other words, lungs are transplanted into those patients
who have been listed for the longest time. Emergency lung transplantation
is almost never possible.
As of January, 2003, there were 3,847 patients on the waiting list
for lung transplantation in the United States. Although the waiting
time for lung transplantation varies from one center to another, the
median waiting time for patients with primary pulmonary hypertension
(PPH), the largest group of patients with PH awaiting transplantation,
is 1152 days. The distribution of donated organs in the United States
is regulated by the United Network for Organ Sharing and additional
information is available on their website (www.unos.org). Outside of
the United States, the process of getting listed for lung transplantation
is, in general, much more difficult and the availability of organs
is much more limited. Additional information about lung transplantation
worldwide is available at the website of the International Society
for Heart and Lung Transplantation (www.ishlt.org)
Deciding the optimal time to be listed for transplantation is often
difficult. This is especially true in patients receiving epoprostenol
(Flolan), although three separate retrospective analyses that included
nearly 400 patients with PPH receiving epoprostenol recently found
that failure to improve clinically or hemodynamically one year after
starting therapy was associated with a significantly worse outcome.
In general, PH in its early stages does not immediately threaten the
life of the patient, so transplantation is not recommended at that
time. On the other hand, the possibility of transplantation should
be discussed before patients are too ill. When transplantation is considered
late in the course of the disease, there is a substantial risk that
the patient will not survive until donor lungs are available. The approach
followed by many centers is to add a patient (if eligible, see below)
to the transplant waiting list at the time he or she initiates epoprostenol
therapy. If the patient subsequently improves with epoprostenol and/or
other treatments, he or she may choose to become inactive on the waiting
list. The accrued waiting time can be saved in case there is a need
to go back on the transplant list in the future. Once listed for transplantation,
patients do have the right to transfer their care and waiting time
to another center. It is also possible to be placed on more than one
list in different geographic regions, but many centers do not allow
this practice.
Transplantation of a single lung works very well for many lung diseases,
and many patients with PH have had a single lung transplant with
good long-term results. However, nearly all transplant centers currently
prefer to transplant both lungs (double-lung transplant) for patients
who have PH, in part because there are generally fewer postoperative
complications. Transplantation of the heart and both lungs (heart-lung
transplant) may be needed in some patients, and in general, waiting
time is longer when more than one organ is needed. As of January,
2003, there were 199 patients listed for heart-lung transplantation.
Living donor lung transplantation (taking a lobe of one lung from
a living person) is possible, but requires two other healthy individuals,
much larger in stature than the recipient, to each donate one lobe
of a lung. Thus, living donor transplantation is mainly performed
in pediatric patients who receive lung tissue from adult donors.
Only 196 living donor transplantations have been performed, and this
option is available at only a few centers.
Candidate selection criteria for lung transplant and post-transplant
treatment regimens vary from center to center. The majority of centers
transplant patients with PPH and congenital heart disease-related PH.
Patients with PH related to diseases that affect more than just the
lungs, such as those with scleroderma, are generally evaluated on a
case by case basis and are not considered for transplantation at some
centers. The age cut-off for listing PH patients is lower than for
patients with other illnesses requiring only single-lung transplantation.
Generally, to be considered for double-lung transplant patients must
be less than 60 years old and for heart-lung transplant they must be
less than 50 years old. Systemic illnesses such as poorly controlled
diabetes with related complications in other organs, significant coronary
artery disease or cancer (other than localized skin cancers) most often
exclude patients from consideration for lung transplantation at the
majority of centers. In addition, a detailed psycho-social evaluation
is performed at all centers to determine whether patients are fully
committed to lung transplantation and whether there will be adequate
social support after transplantation. Support from family or friends
is essential for a successful outcome because of the complicated post-transplant
care. Patients should therefore inquire about the specific acceptance
and rejection criteria at the center performing their evaluation.
Lung transplantation remains the only curative treatment for PH.
However, while it may cure PH, it presents a wide range of new challenges
for patients. Lung transplantation is most effective for patients who
have a positive attitude and are not troubled by the need to take multiple
medications daily or to have frequent medical testing.
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