Chapter 432 Rheumatic Heart Disease
Rheumatic involvement of the valves and endocardium is the most important manifestation of rheumatic fever (Chapter 176). The valvular lesions begin as small verrucae composed of fibrin and blood cells along the borders of one or more of the heart valves. The mitral valve is affected most often, followed in frequency by the aortic valve; right-sided heart manifestations are rare. As the inflammation subsides, the verrucae tend to disappear and leave scar tissue. With repeated attacks of rheumatic fever, new verrucae form near the previous ones, and the mural endocardium and chordae tendineae become involved.
Patterns of Valvular Disease
Mitral Insufficiency
Pathophysiology
Mitral insufficiency is the result of structural changes that usually include some loss of valvular substance and shortening and thickening of the chordae tendineae. During acute rheumatic fever with severe cardiac involvement, heart failure is caused by a combination of mitral insufficiency coupled with inflammatory disease of the pericardium, myocardium, endocardium, and epicardium. Because of the high volume load and inflammatory process, the left ventricle becomes enlarged. The left atrium dilates as blood regurgitates into this chamber. Increased left atrial pressure results in pulmonary congestion and symptoms of left-sided heart failure. Spontaneous improvement usually occurs with time, even in patients in whom mitral insufficiency is severe at the onset. The resultant chronic lesion is most often mild or moderate in severity, and the patient is asymptomatic. More than half of patients with acute mitral insufficiency no longer have the mitral murmur 1 yr later. In patients with severe chronic mitral insufficiency, pulmonary arterial pressure becomes elevated, the right ventricle and atrium become enlarged, and right-sided heart failure subsequently develops.
Clinical Manifestations
The physical signs of mitral insufficiency depend on its severity. With mild disease, signs of heart failure are not present, the precordium is quiet, and auscultation reveals a high-pitched holosystolic murmur at the apex that radiates to the axilla. With severe mitral insufficiency, signs of chronic heart failure may be noted. The heart is enlarged, with a heaving apical left ventricular impulse and often an apical systolic thrill. The 2nd heart sound may be accentuated if pulmonary hypertension is present. A 3rd heart sound is generally prominent. A holosystolic murmur is heard at the apex with radiation to the axilla. A short mid-diastolic rumbling murmur is caused by increased blood flow across the mitral valve as a result of the insufficiency. Auscultation of a diastolic murmur does not necessarily mean that mitral stenosis is present. The latter lesion takes many years to develop and is characterized by a diastolic murmur of greater length, usually with presystolic accentuation.
The electrocardiogram and roentgenograms are normal if the lesion is mild. With more severe insufficiency, the electrocardiogram shows prominent bifid P waves, signs of left ventricular hypertrophy, and associated right ventricular hypertrophy if pulmonary hypertension is present. Roentgenographically, prominence of the left atrium and ventricle can be seen. Congestion of perihilar vessels, a sign of pulmonary venous hypertension, may also be evident. Calcification of the mitral valve is rare in children. Echocardiography shows enlargement of the left atrium and ventricle, an abnormally thickened mitral valve, and Doppler studies demonstrate the severity of the mitral regurgitation. Heart catheterization and left ventriculography are considered only if diagnostic questions are not totally resolved by noninvasive assessment.
Complications
Severe mitral insufficiency may result in cardiac failure that may be precipitated by progression of the rheumatic process, the onset of atrial fibrillation, or infective endocarditis. The effects of chronic mitral insufficiency may become manifest after many years and include right ventricular failure and atrial and ventricular arrhythmias.
Treatment
In patients with mild mitral insufficiency, prophylaxis against recurrences of rheumatic fever is all that is required. Treatment of complicating heart failure (Chapter 436), arrhythmias (Chapter 429), and infective endocarditis (Chapter 431
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