treat any coexisting or causative cardiovascular
disease such as hypertension, ATHEROSCLEROSIS, and
CORONARY ARTERY DISEASE (CAD). Such measures
allow the majority of people who have cardiomy-
opathy, particularly dilative cardiomyopathy, to
enjoy normal lives.
Progressive cardiomyopathy necessitates sub-
stantial lifestyle changes and is a leading cause of
disability due to cardiovascular disease. Hyper-
trophic, ischemic, and restrictive cardiomyopathies
are most likely to be progressive. The therapeutic
approach is to manage symptoms to the extent
possible, making lifestyle adaptations such as
reduced physical activity to accommodate dimin-
ished CARDIAC CAPACITY. Heart transplantation
becomes a treatment option for people under age
65 who are otherwise healthy. Cardiomyopathy
accounts for about half of heart transplantations
performed in the United States. In some situations
an implanted ventricular assist device (VAD) can
supplement the natural heart’s function, allowing
the heart to regain strength and recover from
damage. A VAD also can serve as a “bridge” to
support the heart while a person waits for a donor
heart for transplantation. Sometimes other surgi-
cal approaches, such as removing a segment of
diseased heart tissue to reduce the size of the ven-
tricle, are successful in restoring the heart’s func-
tional ability.
Risk Factors and Preventive Measures
The leading risk factors for most forms of car-
diomyopathy are physical inactivity and subopti-
mal nutrition, which are risk factors for
cardiovascular disease in general, as well as exces-
sive alcohol consumption, genetics, and other car-
diovascular disease. As with any form of
cardiovascular disease, controlling lifestyle factors
reduces the risk for the condition. Early GENETIC
TESTINGcan help people who have family history
of hypertrophic cardiomyopathy to determine
whether they are at risk for this condition and to
plan appropriate therapeutic approaches to delay
its development. Most people who die suddenly
because of hypertrophic cardiomyopathy do not
know they have the condition. Keeping chronic
cardiovascular conditions such as hypertension
and atherosclerosis under control reduces the risk
for secondary cardiomyopathy.
See also ALCOHOLISM; ARRHYTHMIA; BACTERIA; CAR-
DIOVASCULAR DISEASE PREVENTION; CONGENITAL HEART
DISEASE; LIFESTYLE AND CARDIOVASCULAR HEALTH; MED-
ICATIONS TO TREAT CARDIOVASCULAR DISEASE; MUTATION;
QUALITY OF LIFE; RISK FACTORS FOR CARDIOVASCULAR
DISEASE; VENTRICULAR ASSIST DEVICES(VADS); VIRUS.cardiopulmonary bypass A procedure in which
a machine takes over the oxygenation and pump-
ing functions of the LUNGSandHEART, making OPEN
HEART SURGERYpossible. Cardiopulmonary bypass
allows the cardiovascular surgeon to stop the
heart to operate on it, using the bypass machine to
circulate the BLOODthrough the body. Physician
and researcher John H. Gibbon Jr. developed the
first cardiopulmonary bypass machine during
more than two decades of research and experi-
mentation that culminated in its use to repair a
congenital malformation in an 18-year-old
woman’s heart in 1953. Gibbon’s design remains
the foundation of cardiopulmonary bypass
machines in use today.
In cardiopulmonary bypass, the surgeon inserts
large catheters (cannulas) into the VENA CAVAand
the AORTA, then administers a chemical solution to
cause the heart to stop beating (cardioplegia). The
cannulas channel blood through the bypass
machine, which uses a membrane oxygenator to
infuse the blood with oxygen and allow carbon
dioxide to diffuse. Large doses of heparin, an anti-
coagulant medication, keep the blood from clot-
ting, and special filters capture air bubbles. A pump
mechanism, commonly roller pumps or centrifu-
gal force, moves the blood through the bypass
machine and in circulation through the person’s
body. The bypass machine also cools the blood
during surgery, to reduce oxygen consumption by
maintaining the body’s METABOLISMat a lower rate,
and warms it at the conclusion of surgery to pre-
pare for returning the body to its own cardiovas-
cular circulation. At the conclusion of the
OPERATION the surgeon withdraws the cannulas
and restores the flow of blood and the heartbeat.
The primary risks of cardiopulmonary bypass
are blood clots and air bubbles that can cause
embolism (occlusion of a blood vessel), damage to
red blood cells (HEMOLYSIS), and systemic inflam-
matory response (IMMUNE SYSTEMactivation). There
is much debate about whether microemboli thatcardiopulmonary bypass 33