C h a p t e r 1 9
Disorders of Cardiac Function
465
Disorders of the Pericardium
The pericardium is a double-layered fibroserous sac
that encircles the heart. It isolates the heart from other
thoracic structures, maintains its position in the tho-
rax, prevents it from overfilling, and serves as a barrier
to infection. The pericardium consists of two layers: a
thin inner layer, called the visceral pericardium, adheres
to the epicardium; and an outer fibrous layer, called
the parietal pericardium, is attached to the great ves-
sels that enter and leave the heart (see Chapter 17,
Fig. 17-15). The two layers of the pericardium are sep-
arated by a thin layer of serous fluid, which prevents
frictional forces from developing as the heart contracts
and relaxes. Although the fibrous tissue outer layer of
the pericardium allows for moderate changes in cardiac
size, it cannot stretch sufficiently to accommodate rapid
dilation of the heart or accumulation of pericardial
fluid without increasing pericardial and intracardiac
pressures.
The pericardium is subject to many of the same
pathologic processes (e.g., congenital disorders, infec-
tions, trauma, and immune mechanisms) that affect
other structures of the body. Pericardial disorders fre-
quently are associated with other diseases in the heart or
surrounding structures (Chart 19-1). The most common
disorder of the pericardium is acute pericarditis.
Acute Pericarditis
Acute pericarditis, defined as signs and symptoms result-
ing from pericardial inflammation of less than 2 weeks’
duration, may result from an infection or noninfectious
disease. Viral infections (especially infections with cox-
sackieviruses and echoviruses) are themost common cause
of pericarditis and probably are responsible for many
cases of idiopathic or pericarditis of unknown etiology.
Other causes of acute pericarditis include bacterial or
SUMMARY CONCEPTS
■■
Infective endocarditis involves the invasion of
the endocardium by pathogens that produce
vegetative lesions on the endocardial surface.
The loose organization of these lesions permits
the organisms and fragments of the lesions to be
disseminated throughout the systemic circulation.
Although several organisms can cause the
condition, staphylococci have become the leading
cause.Treatment of infective endocarditis focuses
on identifying and eliminating the causative
microorganism, minimizing the residual cardiac
effects, and treating the pathologic effect of emboli.
■■
Rheumatic fever, an immune-mediated,
multisystem inflammatory disease associated
with group A (
β
-hemolytic) streptococcal (GAS)
pharyngitis, can result in serious and disabling
impairment of the heart valves. Primary and
secondary prevention strategies focus on
appropriate antibiotic therapy.
■■
Dysfunction of the heart valves can result from
a number of disorders, including congenital
defects, rheumatic heart disease, trauma,
ischemic heart disease, degenerative changes,
and inflammation. Valvular heart disease causes
disturbances of blood flow. A stenotic valvular
defect is one that causes a decrease in blood flow
through a valve, resulting in impaired emptying
and increased work demands on the heart
chamber that pushes blood across the diseased
valve. A regurgitant valve permits blood flow to
continue despite closure of the valve. Valvular
heart disorders produce blood flow turbulence
and often are detected through heart sound heard
during cardiac auscultation.
CHART 19-1
Classification of Disorders of the
Pericardium*
Idiopathic (no identifiable cause of disease)
■■
Infectious
Viral (echovirus, coxsackievirus, and others)
Bacterial (e.g., Staphylococcus, Streptococcus, Lyme
disease, tuberculosis)
Fungal (Hisplasmosis, candida)
■■
Autoimmune and collagen disorders
Rheumatic fever
Rheumatoid arthritis
Systemic lupus erythematosus
■■
Metabolic disorders
Uremia and dialysis
Myxedema
■■
Ischemia and tissue injury
Myocardial infarction
Cardiac surgery
Chest trauma (blunt and penetrating)
■■
Physical and drug-induced
Radiation therapy
Hydralazine, procainamide, and anticoagulants
Neoplastic Disease
■■
Primary (mesothelioma, fibrosarcoma)
■■
Secondary (e.g., carcinoma of the lung or breast,
lymphoma)
Congenital Disorders
■■
Complete or partial absence of the pericardium
■■
Congenital pericardial cysts
*Chronic inflammatory pericarditis can be associated with
some agents causing an acute inflammatory response.
