Encyclopedia of Health and Medicine

54 The Cardiovascular System
can cause endocarditis; either is potentially life
threatening, though bacterial infection is considerably
more common. Bacterial endocarditis is a
particular risk for people who have certain forms
of CARDIOVASCULAR DISEASE (CVD) and may follow
bacterial infection in other parts of the body. Pathogenic
(infection-causing) BACTERIA may also enter
the BLOOD circulation during dental, diagnostic,
and surgical procedures that cause bleeding.
Endocarditis also occurs as a complication following
valve repair or replacement surgery.
CARDIOVASCULAR CONDITIONS THAT
INCREASE RISK FOR ENDOCARDITIS
cardiopulmonary shunt cyanotic CONGENITAL HEART DISEASE
HEART TRANSPLANTATION hypertrophic CARDIOMYOPATHY
mitral valve prolapse previous bacterial endocarditis
prosthetic heart valves RHEUMATIC HEART DISEASE
uncorrected congenital VALVULAR HEART DISEASE
heart malformations
Symptoms may include COUGH, shortness of
breath (DYSPNEA), and CHEST PAIN. Mild to moderate
FEVER, weight loss, night sweats, and JOINT pain are
also common. Symptoms vary with the location
and nature of the infection and are often vague,
making it challenging for doctors to connect them
to the heart. The diagnostic path includes blood
cultures to determine the presence of bacteria and
ECHOCARDIOGRAM to affirm the inflammation.
Treatment for bacterial endocarditis is intensive
antibiotic therapy, administered intravenously in a
hospital inpatient setting. Treatment for viral
endocarditis is supportive, sometimes requiring
hospitalization to administer intravenous fluids
and medications to ease the heart’s workload until
the infection runs its course. Complications of
either form include endocardial abscesses, valvular
abscesses, and damage to the heart valves. With
appropriate treatment most people recover,
though some may have residual consequences
(such as valve disease) and increased risk for subsequent
infections.
See also ABSCESS; ANTIBIOTIC PROPHYLAXIS;
MYOCARDITIS; PERICARDITIS; VIRUS.
endocardium The membrane that lines the
inner HEART, made up of epithelial cells. The endocardium
also covers the heart valves, providing a
smooth surface that offers no opportunity for
BLOOD cells (particularly platelets) to stick to it as
they pass through the heart. The endocardium
contains Purkinje fibers, specialized MUSCLE cells
that convey the electrical impulses that cause the
heart to contract, and collagen fibers, which give
the endocardium elasticity. The endocardium is
vulnerable to damage from conditions such as
RHEUMATIC HEART DISEASE and VALVULAR HEART DIS-
EASE. These conditions can cause irritation that
inflames the endocardium, making it susceptible
to bacterial INFECTION (ENDOCARDITIS).
For further discussion of the endocardium
within the context of cardiovascular structure and
function, please see the overview section “The
Cardiovascular System.”
See also BACTERIA; MYOCARDIUM; PERICARDIUM;
PLATELET.
enhanced external counterpulsation (EECP) A
therapy for ANGINA PECTORIS that uses sequential
inflation and deflation of cuffs on the legs and
pelvis to assist in returning venous BLOOD to the
HEART and decreasing cardiovascular resistance in
the peripheral arteries. EECP reduces the heart’s
workload during systole, when the ventricles contract,
and increases pressure in the peripheral
arterial network during diastole, when the ventricles
fill. The net effect is that the body’s tissues,
including the heart, receive more blood and thus
more oxygen with less work from the heart.
Researchers arrived at the concept of EECP in
the 1950s. Initial therapeutic efforts were invasive,
withdrawing blood from the femoral veins and
then returning it. Through the ensuing decades
researchers arrived at the method of using compression
cuffs around the calves, thighs, and
pelvis, alternately inflating and deflating them in a
sequence timed with the CARDIAC CYCLE. The cuffs
inflate sequentially from the calves to the pelvis
during diastole and deflate rapidly and simultaneously
during systole. A computer monitors the
cardiac cycle via ELECTROCARDIOGRAM (ECG) and
coordinates the inflation and deflation of the cuffs
accordingly. A therapeutic course involves one
hour of EECP daily for 35 hours (typically five
days a week for seven weeks), performed at a cardiac
clinic or hospital. Most people experience
relief from angina for months to 2 or 3 years.