Page 731 - Cardiac Nursing

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C HAPTER 2 9 / Acquired Valvular Heart Disease 707
DISPLAY 29-2 Indications for Cardiac Surgery DISPLAY 29-3 Risk Factors for Infective Endocarditis
in Infective Endocarditis
Heart failure with hemodynamic instability Recent dental procedure or periodontal disease
Persistent bacteremia and fever despite optimal antibiotic History of congenital heart disease
therapy History of valvular heart disease
Paravalvular abscess or fistula Long-term, in-dwelling intravenous line
Recurrence of endocarditis after full course of antibiotics Genitourinary infections or instrumentation
Systemic emboli Prosthetic valve (mechanical or biologic)
Heart failure due to prosthetic valvular dysfunction History of intravenous drug abuse
Valve dehiscence (in prosthetic valvular endocarditis) Hemodialysis
New conduction system defects
Fungal endocarditis
The American College of Cardiology/American Heart Associ-
ation (ACC/AHA) guidelines now recommend antibiotic prophy- DIAGNOSTIC TESTING FOR
laxis for patients with prosthetic cardiac valves or rings; previous VALVULAR HEART DISEASE
endocarditis; unrepaired cyanotic congenital heart disease; re-
paired congenital heart disease with prosthetic material or residual The diagnosis of valvular heart disease is based on patient history,
defects adjacent to prosthetic device or patch; and cardiac trans- physical assessment, anddiagnostic testing. Some tests, such as
plant recipients. 8
the electrocardiogram and the chest radiograph, may be relatively
insensitive in diagnosing valvular heart disease, even though they
Miscellaneous Causes of are part of the standard screening tests in patients withheart dys-
ValvularDisease function. Both TTE and TEE are used to identify andquantify
valvular heart disease. Diagnostic findings for specific valvular le-
Degenerative changes of the tissue, such as myxomatous degener- sions are noted in the sections discussing each abnormality.
ation, calcification, and changes associated with Marfan syn-
drome, can cause valvular dysfunction. Trauma or infection may
affect the supportive or subvalvular apparatus. Dilation of the
ventricles caused by chronically elevated preloading may dilate an MITRAL STENOSIS
atrioventricular valve opening to the point that the leaflets no
longer approximate and the valve becomes incompetent. Coro- Cause
nary heart disease (CHD) and myocardial infarction can affect the The predominant cause of mitral stenosis is rheumatic fever. The
papillary muscles of the right and left ventricles, causing either mitral valve is the valve most often damagedby rheumatic cardi-
dysfunction caused by ischemia or frank flail of atrioventricular tis. Rheumatic fever causes thickening anddecreased mobility of
9
valve leaflets caused by papillary muscle rupture. Systemic diseases the mitral valve leaflets associated withfusion of the commissures
such as lupus erythematosus and scleroderma may also cause anddestruction of normalleaflet structure. Other conditions that
valvular dysfunction (see Display 29-3). simulate the physiology of mitral stenosis include left atrial myx-
oma, ball-valve left atrial thrombus, large left atrial endocarditis
vegetations, or cor triatriatum (three atria). 10
Pathology
The rheumatic process causes the mitral valve to become fibri-
nous, resulting in leaflet thickening, commissural or chordalfu-
sion, and calcification. As a result, the mitral valve apparatus be-
comes funnel shaped with a narrowed orifice. Fusion of the mitral
valve commissures results in narrowing of the principal orifice,
whereas interchordalfusion obliterates the secondary orifices.
Pathophysiology
Women have mitral stenosis more frequently than men. The nor-
2
mal mitral valve area is 4 to 6 cm . Once the cross-sectional area
2
of the mitral valve is reduced to 2 cm or less, a pressure gradient
between the left atrium andleft ventricle occurs. The reduced ori-
fice impedes left atrial emptying. Increasedleft atrial pressure and
dilation occurs along withleft atrialhypertrophy in an attempt to
■ Figure 29-2 Two-dimensional echocardiogram view of vegetation maintain normaldiastolic flow into the left ventricle. Increased
w
on tricuspid valve in 27-year-old woman with endocarditis (arrow). left atrial pressure is transmitted to the pulmonary circuit, resulting