C h a p t e r 1 9
Disorders of Cardiac Function
471
Clinical Manifestations.
The signs and symptoms of
myocarditis vary from person to person.
53
Some persons
may present with fever, chills, nausea, vomiting, arthral-
gia, and myalgia, occurring up to 6 weeks before the diag-
nosis of myocarditis. Other persons may present with
heart failure without antecedent symptoms. The onset
of heart failure may be gradual or abrupt and fulminant.
Emboli may occur because of the procoagulant effect
of inflammatory cytokines combined with decreased
myocardial contractility. At times, the presentation may
mimic ACS, with ST-segment and T-wave changes, posi-
tive serum cardiac biomarkers, and regional wall motion
abnormalities despite normal coronary arteries. Viral
myocarditis in children or young adults is often nonspe-
cific, with symptoms such as fever and poor eating.
Diagnosis andTreatment.
The diagnosis of myocardi-
tis can be suggested by clinical manifestations. Methods
used in confirming the diagnosis include the ECG, chest
radiography, serum cardiac biomarkers (i.e., creatinine
phosphokinase, troponin I), and echocardiography.
Endomyocardial biopsy findings, obtained through car-
diac catheterization, remain the gold standard for estab-
lishing the diagnosis of acute myocarditis, despite limited
accuracy.
52–54
Many cases of myocarditis are mild and self-limiting,
so first-line treatment remains largely supportive.
52–54
Initial treatments include supplemental oxygen, bed
rest, and antibiotics, if needed. In persons with more
severe myocarditis, arrhythmia suppression and hemo-
dynamic support with vasopressors and positive inotro-
pic agents may be needed. Persons with severe fulminant
myocarditis may require aggressive short-term support
with an intra-aortic balloon pump or left ventricular
assist devices.
52
Immunosuppressive therapy continues
to be investigated. Although treatment of myocarditis
is successful in many persons, some progress to heart
failure. For these patients, cardiac transplantation is an
important intervention.
Peripartum Cardiomyopathy
Peripartum cardiomyopathy is a dilated cardiomyopa-
thy that occurs in the last month of pregnancy or within
5 months after delivery.
55
It is manifested by signs of sys-
tolic dysfunction and heart failure for which there is no
identifiable cause or evidence prior to the last month of
pregnancy.
55–57
The incidence is greater in black, multip-
arous, or older women, and in women with twin fetuses,
preeclampsia, or using tocolytic therapy to prevent pre-
mature labor and delivery.
56,57
Although the etiology of peripartum cardiomyopathy
is unknown, several causes have been proposed, including
infectious, immunologic, nutritional, drug-induced, and
genetic factors. Some women exhibit inflammatory cells
in heart biopsies taken during the symptomatic phase of
the disorder, suggesting a disordered immune response.
Management of peripartum cardiomyopathy includes
standard therapy for heart failure. However, potential
teratogenic effects and the excretion of drugs during
breast-feeding need to be considered. Prognosis depends
on resolution of the heart failure. About half of women
with peripartum cardiomyopathy spontaneously
recover normal cardiac function; the other half are left
with persistent left ventricular dysfunction or progress
to develop heart failure.
57
Stress or “Takotsubo” Cardiomyopathy
First described in Japan in 1991, takotsubo-like left ven-
tricular dysfunction is named after the fishing pot used
to trap octopus that has a narrow neck and wide base,
a shape similar to that of the affected ventricle.
58,59
The
term transient left ventricular apical ballooning has also
been used to describe this syndrome.
An acquired disorder, stress cardiomyopathy has
been identified in the clinical setting as a transient,
reversible left ventricular dysfunction in response to
profound psychological or emotional stress. The syn-
drome occurs primarily in middle-aged women who
present with acute STEMI but who, on cardiac catheter-
ization, have no evidence of CAD. There is, however,
impaired myocardial contractility characterized by left
ventricular apical ballooning with hypercontractility of
the basal left ventricle.
The mechanism for myocardial stunning in stress car-
diomyopathy is unclear, although some theories suggest
ischemia from coronary artery spasm, microvascular
spasm, or direct myocyte injury. When catecholamine
levels return to normal, the interventricular gradient
resolves and left ventricular function recovers.
60
Treatment of stress cardiomyopathy is the same as
that for heart failure, and most patients with takotsubo
cardiomyopathy demonstrate rapid improvement and
an excellent prognosis.
Secondary Cardiomyopathies
Secondary cardiomyopathy is a heart muscle disease in
the presence of a multisystem disorder. The conditions
most commonly associated with secondary cardiomy-
opathies are identified in Chart 19-2. Some of these dis-
orders produce accumulation of abnormal substances
between myocytes (extracellular), whereas others pro-
duce accumulation of abnormal substances within myo-
cytes (intracellular).
Almost 100 distinct myocardial diseases can result in
the clinical features of DCM. They include cardiomyop-
athies associated with drugs, diabetes mellitus, muscular
dystrophy, autoimmune disorders, and cancer treatment
agents (radiation and cancer drugs).
59
Alcoholic cardio-
myopathy is the single most common identifiable cause
of DCM in the United States and Europe. Doxorubicin
(Adriamycin) and other anthracycline drugs used in the
treatment of cancer, are potent agents whose usefulness
is limited by cumulative dose-dependent cardiac toxic-
ity. Another cancer chemotherapeutic agent with cardio-
toxic potential is cyclophosphamide (Cytoxan). Unlike
the primary myocyte injury that occurs with doxorubi-
cin, the principal insult with cyclophosphamide appears
to be vascular, leading to myocardial hemorrhage.
