Chapter 37: Endocarditis

INTRODUCTION

• Endocarditis is an inflammation of the endocardium, the membrane lining the chambers of the heart and covering the cusps of the heart valves. Infective endocarditis (IE) refers to infection of the heart valves by microorganisms, primarily bacteria.

• Endocarditis is often referred to as either acute or subacute depending on the clinical presentation. Acute bacterial endocarditis is a fulminating infection associated with high fevers, systemic toxicity, and death within days to weeks if untreated. Subacute infectious endocarditis is a more indolent infection, usually occurring in a setting of prior valvular heart disease.

ETIOLOGY

• Most patients with IE have risk factors, such as preexisting cardiac valve abnormalities. Many types of structural heart disease resulting in turbulence of blood flow will increase the risk for IE. Some of the most important risk factors include the following:

  • ✔ Highest risk: presence of a prosthetic valve or previous IE

  • ✔ Congenital heart disease (CHD), chronic intravenous (IV) access, diabetes mellitus, acquired valvular dysfunction (eg, rheumatic heart disease), cardiac implantable device, chronic heart failure, mitral valve prolapse with regurgitation, IV drug abuse (IVDA), HIV infection, and poor dentition and/or oral hygiene.

• Three groups of organisms cause most cases of IE: staphylococci, streptococci, and enterococci (Table 37-1). Staphylococci (S. aureus and coagulase-negative staphylococci) are the most common cause of prosthetic valve endocarditis (PVE) within the first year after valve surgery, and S. aureus is common in those with a history of IVDA.

CLINICAL PRESENTATION

• The clinical presentation of patients with IE is highly variable and nonspecific. Fever is the most common finding (more than 90% of patients). The mitral and aortic valves are most often affected.

• IE usually begins insidiously and worsens gradually. Patients may present with nonspecific findings such as fever, chills, weakness, dyspnea, cough, night sweats, weight loss, or malaise.

• Important clinical signs, especially prevalent in subacute illness, may include the following peripheral manifestations (“stigmata”) of endocarditis: Osler nodes, Janeway lesions, splinter hemorrhages, petechiae, clubbing of the fingers, Roth spots, and emboli. The patient may also have a heart murmur (sometimes new or changing), congestive heart failure, cardiac conduction abnormalities, cerebral manifestations, embolic phenomenon, and splenomegaly.

• Without appropriate antimicrobial therapy and surgery, IE is usually fatal. With proper management, recovery can be expected in most patients.

• Factors associated with increased mortality include: congestive heart failure, culture-negative endocarditis, endocarditis caused by resistant organisms such as fungi and gram-negative bacteria, ...