A136 Chapter 7infections and
heart defects
Infections outside the cardiovascular system may eventu-
ally harm the heart. Infections related to an untreated strep
throat, certain dental procedures, or IV drug abuse are in
this category.
Strep infections are caused by strains of Streptococcus
bacteria (Figure 7.22A). If the illness isn’t treated with an
antibiotic, it may lead to rheumatic fever. In this disorder,
the body produces defensive proteins (antibodies) that mis-
takenly attack heart valves. Although in affluent countries
most people who develop strep get treatment, rheumatic
fever still is the most common cause of heart valve disease.
Microbes that enter the bloodstream during a dental
procedure or on a contaminated IV needle may attack
heart valves directly. This condition is called endocarditis
(“inside the heart”). People who have an existing valve
problem due to aging or some other heart disorder often
are advised to take an antibiotic before having dental work.
Endocarditis is a major hazard for IV drug users. It can rap-
idly destroy infected valves and cause sudden heart failure.
Heart problems also can be a complication of Lyme
disease, which is caused by the bacterium Borrelia burgdor-
feri spread by ticks. The body’s first response is a “bull’s-
eye” rash (Figure 7.22B). Later the the heart muscle (the
myocardium) may become inflamed, as may joints. Heart
inflammation, or myocarditis, produces an irregular heart
rhythm that leads to dizzy spells and other symptoms.
Measles caused by the rubella virus can also damage the
heart muscle. Alcohol abuse and recreational drugs also
may cause heart inflammation.
You may have heard of “blue babies”—infants born
with a hole in some part of the heart wall, so that the heart
doesn’t pump blood efficiently. In fact, thousands of babies
enter the world each year with some type of heart defect.
Depending on the problem, one or more surgeries may be
required to repair it.as this chapter’s introduction described, sudden cardiac
arrest is a major medical emergency. unless blood flow
to the brain is restored within about 5 minutes, oxygen-
deprived brain cells die. the need for speed to save the
brain is why nine out of ten sCa victims—from older people
with diagnosed heart disease to seemingly healthy student
athletes—don’t survive.
When sCa strikes, what makes the difference between
life and death? nearly always, the key is a rescuer
who immediately begins chest compressions to keep
blood flowing (Figure 7.23). You’ve probably heard of
Cpr—cardiopulmonary resuscitation. it combines chest
compression with blowing into the victim’s mouth to inflate
the lungs. a newer method, cardiocerebral resuscitation, or
CCr, uses only chest compressions and so doesn’t require
“mouth-to-mouth.” studies show that both methods are
equally effective as first responses to cardiac arrest.
Cpr or CCr may keep blood circulating temporarily, but
neither one restarts a stopped heart. defibrillating drugs
may be used in a hospital, but more often rescuers use a
defibrillator, a device that delivers a strong electrical jolt to
the chest wall and restarts the heart’s pacemaker described
in section 7.4.
as with chest compressions, you don’t need to be a
physician to use a defibrillator. simple training offered
by community organizations is geared toward teaching
ordinary citizens how to use defibrillators known as aeds
(for automatic external defibrillator) in an emergency. today
aeds are a common sight in airports, shopping malls,
schools, and other
public places.
Could you find
the time to learn
to use an aed, do
chest compressions,
or both? if so, you
just might be able
to save a life.Figure 7.23 you may be able to save someone’s life if you learn
how to do CPr or CCr. (A: Faye Norman/SPL/Science Source; B: © Baloncici/
Shutterstock.com)- 9 7. 1 0
how you Can
save a Life
F i g u r e 7. 2 2 infections may lead to heart damage. A Streptococcus
bacteria, which are colored green in this image, cause strep
infections. B Bull’s-eye rash, a key symptom of Lyme disease, the
most common tick-borne disease in the United States.© http://www.zahnarzt
-stuttgart.comAB
Larry Mulvehill/Science SourceBFOCUS ON hUmaN impaCtCopyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).