638
Unit VI Promoting Health in Patients With Circulatory or Perfusion Disorders
Pathophysiology Infective endocarditis is defined as an infection of the innermost layer of the heart, the endocardium, most typ- ically affecting the heart valves. Infective endocarditis begins with damage to the endocardial lining of the heart, which can occur as a result of turbulent blood flow. Tur- bulent blood flow is often caused by valve dysfunction. Platelet and fibrin deposit onto the injured area, forming what is known as a nonbacterial thrombotic endocardial lesion . Microorganisms introduced into the bloodstream through patient exposures circulate and can become trapped under the layers of platelet and fibrin deposits. These microor- ganisms and deposits grow into clumps known as vegeta- tion . This vegetation can severely damage the valves of the heart (Fig. 30.4). The etiology of IE is generally of bacterial origin, although other pathogens have been reported. The most common causative microorganisms are Staphylococcus aureus and Streptococcus . Infective endocarditis can also be caused by other bacteria, viruses, and fungi. The source of expo- sure to microorganisms in the blood has been historically linked to dental and other invasive procedures. However, it has been suggested that repeated exposures to microor- ganisms are more likely to cause IE than random exposure during a single dental or other invasive procedure. Clinical Manifestations Clinical manifestations of IE include red, painful nodes in the pads of the fingers and toes—Osler’s nodes—and red, painless spots on the palms and soles, called Janeway lesions. Splinter hemorrhages, tiny blood clots that run vertically under nails, may also be present . Most patients have a heart murmur , the sound heard when there is turbulent blood flow across a heart valve. They can also experience heart
failure (HF), arrhythmias, weight loss, or night sweats. Other symptoms are similar to those of any infectious pro- cess, such as the following: z Fever z Fatigue z Confusion (in older adults) Interprofessional Management Medical Management Diagnosis Diagnostic Tests Tests used to confirm the diagnosis of IE are blood cul- tures, two sets from different sites, and transthoracic echo- cardiogram (TTE) or transesophageal echocardiogram (TEE). Echocardiography can identify valve dysfunction, vegetative growth, abscesses, and changes in heart size and pumping ability that can occur with IE. Echocardiogra- phy is described in more detail in Chapter 28. An elevated white blood cell count may also be indicative of infection. Medications Medication management consists primarily of IV antibi- otic therapy. The increasing trend of microbial resistance has led to the use of combination therapy. The standard duration of treatment is 4 to 6 weeks but may be longer for prosthetic valves. Patients are often discharged to home on IV antimicrobial therapy. Shorter duration is recom- mended for some combination therapies. Oral antimicro- bial agents are rarely used as initial treatment. Repeated blood cultures may be obtained until results are negative, indicative of adequate bactericidal effects. Prophylactic use of oral antibiotics is not routinely recommended but is used for patients at high risk (see Safety Alert). The choice of antimicrobial agents is complex and based on the organism cultured and the sensitivity report,
Vegetation
Left atrium
Mitral valve
Left ventricle
FIGURE 30.4 Mitral valve vegetation in infective endocarditis.
Powered by FlippingBook