Etiology And Pathogenesis

The exact cause of ARF and rheumatic heart disease (RHD) is unknown. ARF tends to occur after streptococcal pharyngitis rather than cellulitis. The familial tendency toward ARF is well documented. The HLA-DR2 and DR4 antigens have been linked to an increased incidence of ARF.

The virulence of GAS is related to the bacterial M protein, which structurally resembles human myosin. It is presumed that GAS adheres to the pharyngeal mucosa of the patient and activates antigens and superantigens, which triggers an immune response. In genetically susceptible individuals, antibodies against myosin are produced, which can lead to carditis. Repeated untreated infections with GAS may reactivate antibody production and lead to an autoimmune response that lasts several weeks and eventually damages heart valves (Figure 49-2).

Figure 49-2 Manifestations of acute rheumatic carditis.

Clinical Presentation

The diagnosis of ARF is challenging for several reasons. Pharyngitis is a common complaint in the pediatric population. About 70% of older children and young adults with ARF will recollect an antecedent pharyngitis, but only 20% of young children will. There is an average latent period from the onset of streptococcal pharyngitis to ARF of 18 days (range, 1-5 weeks), which can make recollection during the history challenging. Thus, GAS is rarely isolated from the oropharynx in patients with ARF. Typically, the first manifestation is a painful migratory polyarthritis, but 10% of rheumatic patients will present with pure chorea and no other manifestations of rheumatic fever.

More than 60 years ago, T. Duckett Jones published guidelines for diagnosis of ARF that have been slightly revised by the World Health Organization (Box 49-1 and Figure 49-3). To make a primary diagnosis of ARF, two major or one major and two minor criteria plus evidence of a preceding GAS infection are needed. The exception is rheumatic chorea. Sydenham’s chorea (St. Vitus dance) in isolation is considered diagnostic, and no other criteria or evidence of GAS infection are required to make the diagnosis.

Figure 49-3 Noncardiac manifestations of acute rheumatic fever.

Acute carditis is usually clinically manifest by sinus tachycardia without diurnal variation and new onset of a heart murmur of mitral regurgitation with or without aortic regurgitation. With a single attack of ARF, the mitral regurgitation often resolves over months to years, but aortic regurgitation is more likely to persist. In severe cases, signs of heart failure or a friction rub from pericarditis may also be present.

Chronic RHD results when a single or multiple attacks of ARF deform and fuse valve cusps, commissures, or chordae. Stenosis or insufficiency of the valve, and often both, occur. Isolated mitral valve involvement occurs in 60% to 70%, mitral and aortic involvement in 20%, and isolated aortic involvement is rare. The tricuspid valve is involved in 5% to 10% but occurs with mitral or aortic disease. Pulmonary valve involvement is rare.

A history of ARF is obtained in only 60% of patients with RHD. Whereas chronic mitral regurgitation is the most common form of RHD in children and young adults (Figure 49-4), mitral stenosis is more common in older adults. Aortic regurgitation, although less common than mitral regurgitation with ARF, is more likely to persist (see Figure 49-4). Patients with mitral or aortic valve disease may present with an isolated heart murmur or palpitations caused by atrial arrhythmias. They can present with fatigue, decreased exercise tolerance, dyspnea on exertion, orthopnea, and paroxysmal nocturnal dyspnea, which can represent low cardiac output or pulmonary hypertension. However, the onset of symptoms can often be so insidious that patients adapt and are unaware of their significant functional limitations.

Figure 49-4 Rheumatic heart disease: clinical presentation.