Pathologic Criteria

Microorganisms, demonstrated by culture or histologic examination, in a vegetation, embolus from a vegetation, or intracardiac abscess

Histologic confirmation of active endocarditis in vegetation or intracardiac abscess

Clinical Criteria

Major

Positive blood culture(s) indicating characteristic organism or persistence of unusual organism

Echocardiographic findings, including valve-related or implant-related mass or abscess, or partial separation of artificial valve

New valvular regurgitation

Minor

Predisposing heart lesion or intravenous drug use

Fever

Vascular lesions, including arterial petechiae, subungual/splinter hemorrhages, emboli, septic infarcts, mycotic aneurysm, intracranial hemorrhage, Janeway lesions †

Immunologic phenomena, including glomerulonephritis, Osler nodes, ‡ Roth spots, § rheumatoid factor

Microbiologic evidence, including single culture showing uncharacteristic organism

Echocardiographic findings consistent with but not diagnostic of endocarditis, including new valvular regurgitation, pericarditis

*Diagnosis by these guidelines, often called the Duke Criteria, requires either pathologic or clinical criteria; if clinical criteria are used, 2 major, 1 major + 3 minor, or 5 minor criteria are

required for diagnosis. Modified from Durack DT, et al: Am J Med, 96:200, 1994 and Karchmer AW, In Braunwald E, Zipes DP, Libby P (eds): Heart Disease. A Textbook of

Cardiovascular Medicine, 6th ed. Philadelphia, WB Saunders Co., 2001, p. 1723.

†Janeway lesions are small erythematous or hemorrhagic, macular, nontender lesions on the palms and soles and are the consequence of septic embolic events.

‡Osler nodes are small, tender subcutaneous nodules that develop in the pulp of the digits or occasionally more proximally in the fingers and persist for hours to several days.

§Roth spots are oval retinal hemorrhages with pale centers.

NONINFECTED VEGETATIONS

Nonbacterial Thrombotic Endocarditis (NBTE)

NBTE is characterized by the deposition of small masses of fibrin, platelets, and other blood components on the leaflets of the cardiac valves. In contrast to the vegetations of IE, discussed

previously, the valvular lesions of NBTE are sterile and do not contain microorganisms. NBTE is often encountered in debilitated patients, such as those with cancer or sepsis—hence the

previously used term marantic endocarditis. Although the local effect on the valves is usually unimportant, NBTE may achieve clinical significance by producing emboli and resultant

infarcts in the brain, heart, or elsewhere.

Morphology.

In contrast to IE, the vegetations of NBTE are sterile, nondestructive, and small (1 to 5 mm), and occur singly or multiply along the line of closure of the leaflets or cusps ( Fig. 12-28 ).

Histologically, they are composed of bland thrombus without accompanying inflammatory reaction or induced valve damage. Should the patient survive the underlying disease,

organization may occur, leaving delicate strands of fibrous tissue.

Pathogenesis.

NBTE frequently occurs concomitantly with venous thromboses or pulmonary embolism, suggesting a common origin in a hypercoagulable state with systemic activation of blood

coagulation such as disseminated intravascular coagulation ( Chapter 4 ). This may be related to some underlying disease, such as a cancer, and, in particular, mucinous adenocarcinomas

of the pancreas. The striking association with mucinous adenocarcinomas in general may relate to the procoagulant effect of circulating mucin, and thus NBTE can be a part of the

Trousseau syndrome ( Chapter 7 ). Lesions of NBTE, however, are also seen occasionally in association with nonmucin-producing malignancy, such as acute promyelocytic leukemia, and

in other debilitating diseases or conditions (e.g., hyperestrogenic states, extensive burns, or sepsis) promoting hypercoagulability. Endocardial trauma, as from an indwelling catheter, is

also a well-recognized predisposing condition, and one frequently notes right-sided valvular and endocardial thrombotic lesions along the track of a Swan-Ganz pulmonary artery catheter.

Endocarditis of Systemic Lupus Erythematosus (Libman-Sacks Disease)

In SLE, mitral and tricuspid valvulitis with small, sterile vegetations, called Libman-Sacks endocarditis is occasionally encountered.

Morphology.

The lesions are small single or multiple, sterile, granular pink vegetations ranging from 1 to 4 mm in diameter. The lesions may be located on the undersurfaces of the atrioventricular

valves, on the valvular endocardium, on the cords, or on the mural endocardium of atria or ventricles. Histologically the verrucae consist of a finely granular, fibrinous eosinophilic

material that may contain hematoxylin bodies (the tissue equivalent of the lupus erythematosus cell of the blood and bone marrow, see Chapter 6 ). An intense valvulitis may be present,

characterized by fibrinoid necrosis of the valve substance that is often contiguous with the vegetation. Leaflet vegetations can be difficult in some cases to distinguish from those of IE or

NBTE (see Fig. 12-27 ). Subsequent fibrosis and serious deformity can result that resemble chronic RHD and require surgery.

Thrombotic heart valve lesions with sterile vegetations or rarely fibrous thickening commonly occur with the antiphospholipid

Figure 12-28Nonbacterial thrombotic endocarditis (NBTE). A, Nearly complete row of thrombotic vegetations along the line of closure of the mitral valve leaflets (arrows). B,

Photomicrograph of NBTE, showing bland thrombus, with virtually no inflammation in the valve cusp (c) or the thrombotic deposit (t). The thrombus is only loosely attached to the cusp

(arrow).

Figure 12-29Carcinoid heart disease. A, Characteristic endocardial fibrotic lesion involving the right ventricle and tricuspid valve. B, Microscopic appearance of carcinoid heart disease

with intimal thickening. Movat stain shows underlying myocardial elastic tissue black and acid mucopolysaccharides blue-green.

Figure 12-30Complications of artificial heart valves. A, Thrombosis of a mechanical prosthetic valve. B, Calcification with secondary tearing of a porcine bioprosthetic heart valve,

viewed from the inflow aspect.

TABLE 12-9-- Causes of Failure of Cardiac Valve Prostheses

Thrombosis/thromboembolism

Anticoagulant-related hemorrhage

Prosthetic valve endocarditis

Structural deterioration (intrinsic)

••Wear, fracture, poppet failure in ball valves, cuspal tear, calcification

Nonstructural dysfunction

••Granulation tissue, suture, tissue entrapment, paravalvular leak, disproportion, hemolytic anemia, noise

Cardiomyopathies

The previous sections emphasize that myocardial dysfunction occurs commonly but secondarily in a number of different conditions such as ischemic heart disease, hypertension, and

valvular heart disease. Far less frequently observed is disease whose cause is intrinsic to the myocardium. Myocardial diseases are a diverse group that includes inflammatory disorders

(myocarditis), immunologic diseases, systemic metabolic disorders, muscular dystrophies, genetic abnormalities in cardiac muscle cells, and an additional group of diseases of unknown

etiology.

The term cardiomyopathy (literally, heart muscle disease) is used to describe heart disease resulting from a primary abnormality in the myocardium.[95] Although chronic myocardial

dysfunction due to ischemia should be excluded from the cardiomyopathy rubric, the term ischemic cardiomyopathy has gained some popularity among clinicians to describe CHF caused

by CAD (as discussed in the section "Chronic Ischemic Heart Disease").

In many cases cardiomyopathies are idiopathic (i.e., of unknown cause). However, a major advance in our understanding of myocardial diseases, previously considered idiopathic, has been

the demonstration that specific genetic abnormalities in cardiac energy metabolism or structural and contractile proteins underlie myocardial dysfunction in many patients.[96] [97] [98] Thus,

etiologic distinctions have become somewhat blurred in recent years. Moreover, myocardial disease of diverse and even unknown etiologies may have a similar morphologic appearance.

Therefore, our discussion avoids the controversies associated with classification schemes and emphasizes clinicopathologic, etiologic, and mechanistic concepts.

Without additional data, the clinician encountering a patient with myocardial disease is usually unaware of the etiology. Hence the clinical approach is largely determined by one of the

following three clinical, functional, and pathologic patterns ( Fig. 12-31 and Table 12-10 ):

• Dilated cardiomyopathy

• Hypertrophic cardiomyopathy

• Restrictive cardiomyopathy

Among these three categories, the dilated form is most common (90% of cases), and the restrictive is least prevalent. Within the hemodynamic patterns of myocardial dysfunction, there is

a spectrum of clinical severity, and overlap of clinical features often occurs between groups. Moreover, each of these patterns can be either idiopathic or due to a specific identifiable cause

( Table 12-11 ) or secondary to primary extramyocardial disease.

Endomyocardial biopsies are used in the diagnosis and management of patients with myocardial disease and in cardiac transplant recipients. Endomyocardial biopsy involves inserting a

device (called a bioptome) transvenously into the right side of the heart and snipping a small piece of septal myocardium in its jaws, which is then analyzed by a pathologist.[99]

Date: 2016-04-22; view: 859