INFECTIVE ENDOCARDITIS

Definition

According to Lewis,

Infective endocarditis, previously known as bacterial endocarditis, is an infection of the endocardial surface of the heart. The endocardium, the inner layer of the heart, is contiguous with the valves of the heart. Therdore inflammation from infective endocarditis usually affects the cardiac valves.

According to Mosby

Endocarditis is an inflammatory process involving the endothelial layer of the heart, including the cardiac valves and septal defects ( if present)

According to Lippincott,

Infectious endocarditis (IE) is a disease in which infective organisms invade the endothelial lining of the heart, usually involving one or more valves. This is the major endocardial disease . the endocardium covers the valves and surrounds the chordae tendineae. The infection that forms, usually on the valve of the heart is called vegetation.

Etiology

The most common causative agents are bacterial, especially staphylococcus aureus, streptococcus viridians , streptococcus pyogenes (a type of group A streptococcus ), and streptococcus pneumonia. Other possible pathogens include fungi, chlamydiae, rickettsiae, and viruses.

Predisposing factors for infectious endocarditis

Male sex

Rheumatic heart disease

Degenerative valvular disease

Aortic or mitral valve disease

Prosthetic cardiac valve

Ventricular septal defect Coarctation of the aorta Patent ductus arteriosus

Hypertrophic cardiomyopathy owth left ventricular outflow tarct obstruction

Intravenous drug use

Diabetes mellitus

Pregnancy

Marfan’s syndrome

Central venous and pulmonary artery catheters

Classification

Two forms of infective endocarditis, subacute and acute. The subacute form has a longer clinical course of more insidious onset and the causative organism is usually of low virulence.

The acute form has a shorter clinical course with a more rapid onset and the organism is more virulent.

Pathogenesis

Due to causative organism and circulating bacteria

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Damage to the valvular endothelium , the formation of a platelet – fibrin thrombus and adherenece of bacteria

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Formation of platelet thrombin plaque, followed by the proliferation of the infecting organism

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Nonbacterial thrombotic endocarditis lesion (NBTE )

Clinical features

Fever occurs in more than 90% of patients.

Other nonspecific manifestations that may accompany fever fever include chills, weakness, malaise, fatigye, and anorexia. Arthralgia, myalgias, back pain, abdominal discomfort, weight loss, hedace, and clubbing of fingers may occur in subacute forms of endocarditis.