MYOCARDITIS
Myocarditis
is an inflammatory process involving the myocardium. Myocarditis can cause
heart dilation, thrombi on the heart wall (mural thrombi), infiltration of
circulating blood cells around the coronary vessels and between the muscle
fibers, and degeneration of the muscle fibers themselves. The incidence of
myocarditis is estimated to be 1 to 10 cases per 100,000 persons. The rate may
be higher because the variety of clinical presentations may cause
underreporting (Tang, 2001). Mortality varies with the severity of symptoms.
Most patients with mild symptoms recover com-pletely. Other patients may
develop cardiomyopathy and heart failure. Patients with symptomatic heart
failure and an ejection fraction of less than 45% had a 1-year mortality rate
of 20% and a 4-year mortality rate of 56% (Tang, 2001).
Myocarditis
usually results from a viral, bacterial, mycotic, para-sitic, protozoal, or
spirochetal infection. It also may occur in pa-tients after acute systemic
infections such as rheumatic fever, in those receiving immunosuppressive
therapy, or in those with in-fective endocarditis. Myocarditis may result from
an allergic re-action to pharmacologic agents used in the treatment of other
diseases. It may begin in one small area and then spread through-out the
myocardium. The degree of myocardial involvement de-termines the degree of
hemodynamic effect and resulting signs and symptoms. It is theorized that
dilated cardiomyopathy is a la-tent manifestation of myocarditis.
The
symptoms of acute myocarditis depend on the type of infec-tion, the degree of
myocardial damage, and the capacity of the myocardium to recover. The patient
may be asymptomatic, andthe infection resolves on its own. The patient may
develop mild to moderate symptoms and seek medical attention. The patient may
also sustain sudden cardiac death or quickly develop severe congestive heart
failure. The patient with mild to moderate symptoms often complains of fatigue
and dyspnea, palpitations, and occasional discomfort in the chest and upper
abdomen.
Assessment
of the patient may reveal no abnormalities; as a result, the entire illness
goes unrecognized. The patient may complain of chest pain (with a subsequent
cardiac catheterization demon-strating normal coronary arteries). The patient without
any ab-normal heart structure (at least initially) may suddenly develop
dysrhythmias. If the patient has developed structural abnormali-ties (eg,
systolic dysfunction), the clinical assessment may disclose cardiac
enlargement, faint heart sounds, gallop rhythm, and a sys-tolic murmur.
Prevention
of infectious diseases by means of appropriate immu-nizations (eg, influenza,
hepatitis) and early treatment appears to be important in decreasing the
incidence of myocarditis (Braunwald et al., 2001).
The
patient receives specific treatment for the underlying cause if it is known
(eg, penicillin for hemolytic streptococci) and is placed on bed rest to
decrease the cardiac workload. Bed rest also helps to decrease myocardial damage
and the complications of myocarditis. Activities, especially sports in young
patients with myocarditis, should be limited for a 6-month period or at least
until heart size and function have returned to normal. Physical activity is
increased slowly, and the patient is instructed to report any symptoms that
occur with increasing activity, such as a rapidly beating heart. The use of
corticosteroids in treating myo-carditis remains controversial (Braunwald et
al., 2001). Non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin and
ibuprofen are not to be used during the acute phase or if the pa-tient develops
heart failure, because these medications can cause further myocardial damage.
If the patient develops heart failure, management is essentially the same as
for all causes of heart failure .
The
nurse assesses the patient’s temperature to determine whether the disease is
subsiding. The cardiovascular assessment focuses on signs and symptoms of heart
failure and dysrhythmia. The patient experiencing dysrhythmias should receive
continuous cardiac monitoring with personnel and equipment readily available to
treat life-threatening dysrhythmias.Elastic compression stockings and passive
and active exercises should be used, because embolization from venous
thrombosis and mural thrombi can occur.
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