Rheumatic Heart Disease
Rheumatic fever is an acute autoimmune disorder that results as a complication of streptococcal upper respiratory tract infections. Tissues involved in rheumatic fever include the lining and valves of the heart, skin, and connective tissue (
Fig. 29-1). The group A β-hemolytic streptococcal organism is responsible for initial and recurrent attacks of rheumatic fever. Lymphatic channels from the tonsils are thought to transmit group A streptococci to the heart.
The incidence of rheumatic fever has declined to less than 1/100,000 in industrialized nations but remains higher than 100/100,000 in endemic, less developed countries.
1 Reasons for the decline in rheumatic fever include the use of antibiotics to treat and prevent streptococcal infections, as well as improved social conditions such as decreased crowding, better housing and sanitation, and access to health care. Rheumatic fever persists in underdeveloped countries in which socioeconomic conditions enable the spread of streptococcal bacteria and limit access to adequate health care. Acute rheumatic fever involves diffuse exudative and proliferative inflammatory reactions in the heart, joints, and skin.
Jones criteria, based on expert opinion rather than clinical trials, were introduced in 1944 for the diagnosis of rheumatic fever. Major diagnostic criteria include carditis, polyarthritis, chorea, erythema marginatum (pink skin rash), and subcutaneous nodules. Minor criteria include arthralgia, fever, and elevated C-reactive protein.
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Carditis is the most important clinical manifestation of acute rheumatic fever, causing inflammation of the endocardium, myocardium, and pericardium. Myocarditis is characterized by interstitial inflammation that may affect cardiac conduction. Endocarditis causes extensive inflammatory changes, resulting in scarring of the heart valves and acute heart failure. Warty lesions of eosinophilic material build-up at the bases and edges of the valves. As the lesions progress, granulation tissue and subsequent vascularization develop, and fibrosis occurs. The annulus, cusps, and chordae tendineae are scarred and, as a result, they thicken and shorten. Acute heart failure develops because of interstitial myocarditis. Fibrinoid degeneration develops, followed by the appearance of Aschoff nodules, the characteristic pathologic lesion of acute rheumatic fever. As Aschoff nodules heal, fibrous scars remain. In severe cases, death from acute heart failure may result. Carditis frequently does not cause any symptoms and is detected only when the patient seeks help because of arthritis or chorea.
Auscultatory signs of aortic and mitral insufficiency are frequently apparent. In more than 90% of patients with carditis, the mitral valve is affected. When the mitral valve is affected, there may be a high-pitched, blowing, pansystolic murmur. A Carey Coombs murmur, a low-pitched, mid-diastolic murmur of short duration, may be noted at the apex. The Carey Coombs murmur may be attributed to swelling and stiffening of mitral valve leaflets, increased flow across the valve, and alteration in left ventricular compliance.
Rheumatic fever can be prevented by aggressive treatment of the initial episode of streptococcal pharyngitis: penicillin G, 500 mg as the first dose and then 250 mg four times daily for a duration of 10 days. If the patient is allergic to penicillin, erythromycin or cephalosporins may be used. Effective antibiotic treatment started less than 10 days after the onset of infection almost completely eliminates the risk of rheumatic fever.
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Infective Endocarditis
Infective endocarditis is an endovascular infection that supports continuous bacteremia from the source of the infection, usually a vegetation on a heart valve.
2 While endocarditis is uncommon, affecting
only 10,000 to 20,000 people in the United States each year, it may result in serious complications such as stroke, need for surgery, and death.
3 Although incidence of infective endocarditis is low, between 1.5 and 6 cases per 100 cases per year, morbidity and mortality are high.
4 In intravenous drug users, the risk for endocarditis is 2% to 5% per patient-year.
5 Rheumatic heart disease, calcific aortic stenosis, hypertrophic cardiomyopathy, congenital heart disease, and the presence of prosthetic heart valves predispose to endocarditis. Intravenous drug abusers are at risk for infective endocarditis caused by recurrent bacteremias related to injection from contaminated needles and localized infections at injection sites. Patients with long-term intravenous lines or dialysis catheters are also at increased risk. Acute endocarditis can also occur in normal heart valves from infection somewhere else in the body In patients with community-acquired, native valve endocarditis,
Staphylococcus aureus exceeds streptococci as the causative pathogen.
5 Pathogens that are most commonly responsible for subacute endocarditis include streptococci, enterococci, coagulase-negative staphylococci, and the HACEK group of organisms (
Haemophilus species,
Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella species, and
Kingella kingae). Clinical presentations of endocarditis range from fever and malaise to symptoms related to systemic emboli (
Table 29-1).
The pathologic process of endocarditis requires that several conditions exist to permit infection to grow in the heart and to promote an environment that supports growth on the endocardial surface. For endocarditis to develop, there is first endocardial injury with thrombus formation at the site. Transient or persistent bacteremia allows bacteria to adhere to the injured surface. Infected vegetations result and may fragment and embolize.
5 The complications of infective endocarditis include congestive heart failure (CHF), paravalvular abscess formation, embolic events to the brain or other organs, sepsis, pericarditis, renal failure, and metastatic abscesses.
4 The reduction in mortality for infective endocarditis over the past 30 years from 25% to 30% down to 10% to 20% may be largely related to aggressive surgical intervention in cases complicated by CHF, invasive abscesses, and prosthetic valve infections.
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Blood cultures are an essential diagnostic tool in infective endocarditis. Three separate sets of blood cultures drawn from different venipuncture sites, obtained over 24 hours, usually identify the organism. Patients with infective endocarditis whose cultures remain negative may have fastidious organisms or may have received intravenous antibiotics before blood samples were drawn. In acute endocarditis, antibiotic therapy should be started after blood cultures have been obtained using strict aseptic technique and optimal skin preparation.
2 The clinical approach in acute endocarditis includes appropriate antibiotics and monitoring for complications (
Display 29-1). The usual course is 6 full weeks of intravenous antibiotics. Patients who do not respond well to standard antibiotic therapy may be referred for surgical valve replacement (
Display 29-2).
Echocardiography is frequently used to verify the presence of vegetations on the valves (
Fig. 29-2). Transesophageal echocardiography (TEE) provides better resolution and can identify smaller vegetations than transthoracic echocardiography (TTE).
5 TEE is also useful to identify paravalvular leaks and annular abscesses seen in prosthetic valve endocarditis. Although TEE is more sensitive, some clinicians recommend to obtain TTE first and to perform TEE only if the TTE images are inadequate or suspicion of infective endocarditis remains high and the initial TTE was negative.
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The American College of Cardiology/American Heart Association (ACC/AHA) guidelines now recommend antibiotic prophylaxis for patients with prosthetic cardiac valves or rings; previous endocarditis; unrepaired cyanotic congenital heart disease; repaired congenital heart disease with prosthetic material or residual defects adjacent to prosthetic device or patch; and cardiac transplant recipients.
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