460
U N I T 5
Circulatory Function
have a streptococcal infection). Thus a negative antigen
test result should be confirmed with a throat culture
when a streptococcal infection is suspected.
36
Treatment of acute RF is designed to control the acute
inflammatory response and prevent cardiac complica-
tions and recurrence of the disease. During the acute
phase, antibiotics, anti-inflammatory drugs, and selec-
tive restriction of activities are prescribed. Penicillin,
or another antibiotic in penicillin-sensitive patients, is
the treatment of choice.
36
Salicylates and corticosteroids
can be used to suppress the inflammatory response, but
should not be given until the diagnosis of RF is con-
firmed. Surgery, including valve repair and replacement,
is indicated for chronic rheumatic valve disease and is
determined by the severity of the symptoms or cardiac
dysfunction.
Persons who had RF are at high risk for recurrence
after subsequent GAS throat infections. Penicillin is the
treatment of choice for secondary prophylaxis, but sul-
fadiazine or erythromycin may be used in those who
are allergic to penicillin. The duration of prophylaxis
depends on whether residual valvular disease is present
or absent. It is recommended that persons with persis-
tent valvular disease receive low-dose antibiotic prophy-
laxis for at least 5 years after the acute episode of RF
or until age 21 years if there is no evidence of carditis.
35
Valvular Heart Disease
The past several decades have brought remarkable
advances in the treatment of valvular heart disease. This
is undoubtedly due to improved methods for noninva-
sive monitoring of ventricular function, improvement
in prosthetic valves, advances in valve reconstruction,
and the development of guidelines to improve the timing
of surgical interventions.
37
Nevertheless, valvular heart
disease continues to produce considerable mortality and
morbidity.
Hemodynamic Derangements
The function of the heart valves is to promote unidi-
rectional flow of blood through the chambers of the
heart. Dysfunction of the valves can result from a num-
ber of disorders including congenital defects, trauma,
ischemia, degenerative changes, and inflammation.
Although any of the heart valves can become diseased,
the most commonly involved are the mitral and aortic
valves. Disorders of the pulmonary and tricuspid valves
are less common, probably because of the low pressure
in the right side of the heart.
The heart valves consist of thin leaflets of tough, flex-
ible, endothelium-covered fibrous tissue firmly attached
at the base to the fibrous valve rings (see Chapter 17).
The leaflets of the heart valves may be damaged or
inflammed, which can deform their line of closure.
Healing of the valve leaflets is associated with increased
collagen content and scarring, causing the leaflets to
shorten and stiffen. Another problem is that the edges
of the healing valve leaflets can fuse together so that the
valve does not open or close properly.
Two types of mechanical disruption occur with val-
vular heart disease: narrowing of the valvular opening,
so it does not open properly, and distortion of the valve,
so it does not close properly (Fig. 19-13).
Stenosis
refers
to a narrowing of the valve orifice and failure of the
valve leaflets to open normally (Fig. 19-14). Significant
narrowing of the valve orifice increases the resistance to
blood flow through the valve, converting the normally
smooth laminar flow to a less efficient turbulent flow.
This increases the work and volume of the chamber
emptying through the narrowed valve—the left atrium
in the case of mitral stenosis and the left ventricle in aor-
tic stenosis. An
incompetent
or
regurgitant
valve does
not close properly, thereby permitting the backward
flow of blood to occur when the valve should be closed.
When the aortic valve is affected, blood flows back into
the left ventricle during diastole. When the mitral valve
is affected, blood flows back into the left atrium dur-
ing systole. Stenosis and regurgitation can occur in pure
forms, or these abnormalities may exist in the same
valve. Alterations in hemodynamic function that accom-
pany aortic and mitral valve stenosis and regurgitation
are illustrated in Figure 19-15.
FIGURE 19-13.
Disease of the aortic valve as viewed from the
aorta.
(A)
Stenosis of the valve opening.
(B)
An incompetent or
regurgitant valve that is unable to close completely.
Thickened and
stenotic valve
leaflets
A
Retracted
fibrosed valve
leaflets
B
FIGURE 19-14.
Gross pathology of rheumatic heart disease:
aortic stenosis. Fused aortic valve leaflets and opened coronary
arteries from above. (From the Centers for Disease Control and
Prevention Public Health Images Library No. 848. Courtesy of
Edwin P. Ewing, Jr.)
