Encyclopedia of Health and Medicine

62 The Cardiovascular System
• PERIPHERAL VASCULAR DISEASE (PVD) with symptoms
such as INTERMITTENT CLAUDICATION
• TRANSIENT ISCHEMIC ATTACK (TIA)
• PRIMARY PULMONARY HYPERTENSION (PPH), CHRONIC
OBSTRUCTIVE PULMONARY DISEASE (COPD), EMPHY-
SEMA, or severe ASTHMA
• OBESITY
Though none of these criteria is absolute,
because of the extreme limited availability of
donor hearts cardiologists must be able to justify
exceptions. Heart transplantation centers set their
own criteria, which may be more or less stringent
than the general criteria. Many heart transplantation
centers are reluctant to approve individuals
who are not likely to maintain the rigorous therapeutic
and lifestyle regimens necessary following
transplant. In infants and children, heart transplantation
is an option for nonsurvivable major
congenital anomalies. The shortage of donor
hearts severely limits heart transplantation in
infants, however.
The donor heart The United Network for Organ
Sharing (UNOS) maintains donor lists for all transplant
circumstances (except corneas and SKIN) in
the United States. UNOS coordinates the acquisition
and distribution of donor organs according to
strict guidelines and policies that direct available
organs to the sickest people on the waiting lists for
whom criteria match. Regional transplantation
centers carry out the acquisitions and distributions.
People waiting for heart transplants must be
available 24 hours a day and must be able to reach
their transplantation centers within two hours.
The donor’s BLOOD TYPE must be the same as the
recipient’s, and the donor and recipient need to be
similar in body size and weight. The heart of a
donor who is six feet, four inches tall will not fit
in the chest cavity of a recipient who is five feet,
three inches tall. Similarly, the heart of a small
donor cannot meet the cardiovascular needs of a
large recipient. Gender, race, and ethnicity do not
matter. The donor’s heart must be healthy, and
the donor must be under age 65 and free from
serious or communicable diseases. Most donor
hearts come from people who lose their lives in
accidents that cause irreversible, overwhelming
BRAIN damage. A specialized surgical team carefully
harvests the heart in the operating room,
after certifying brain death though while cardiovascular
function continues, and places the heart
in a cold electrolyte solution to preserve it during
transport to the recipient’s medical center. The
heart remains viable for four to six hours.
Surgical Procedure
The heart transplant operation typically takes three
to five hours. The surgeon opens the chest with a
large incision lengthwise over the STERNUM and cuts
the sternum with a saw to open the chest. After
placing the person on CARDIOPULMONARY BYPASS
(mechanical oxygenation and circulation of the
blood), the surgeon removes the diseased heart.
There are several methods for doing this; the most
common is to cut away all of the heart except the
back walls of the atria to preserve the connections
to their blood vessels (the superior VENA CAVA, inferior
vena cava, and pulmonary VEIN). Respectively,
the surgeons cut away the back of the donor heart
to match and suture the donor heart into place
beginning with the left atrium. The great arteries—
the AORTA and the pulmonary ARTERY—are the final
structures the surgeon attaches. The heart spontaneously
begins to beat when the surgeon restores
blood flow. The surgeon closes the sternum with
wire to hold it together while it heals, and closes
the outer chest tissues with sutures or staples. Most
people remain in the hospital up to 10 days following
surgery.
Risks and Complications
Heart transplantation entails numerous risks and
complications during (operative) and following
(postoperative) the surgery. Operative risks
include bleeding, air embolism (air that escapes
into the bloodstream from the cardiopulmonary
bypass), unexpected anatomic incompatibilities
(the donor heart does not “fit”), and inability to
restore cardiac function. The most significant complications
following heart transplantation, which
also account for the greatest number of deaths, are
INFECTION and rejection. Arrhythmias and other
dysfunctions of the heart sometimes occur, though
typically respond to medications. Occasionally the
transplanted heart fails to function, a circumstance
called graft failure. Immediate retransplantation is
generally the only treatment.