sábado, 23 de febrero de 2019

Rheumatic Fever Diagnosis

Download PDF Copy

Rheumatic fever represents an autoimmune disease following infection with group A streptococcus (Streptococcus pyogenes), which is one of the most ubiquitous of human pathogens. The disease is characterized by multiple focal inflammatory lesions of the connective tissue structures – particularly of the heart, blood vessels and joints.

Rheumatic fever remains one of the major causes of childhood cardiac disease in developing nations and a serious public health problem throughout the world. Hence adequate diagnosis and management are of utter most importance, as damage to cardiac valves may be chronic and progressive, and subsequently result in cardiac decompensation.

Jones criteria

The diagnosis of acute rheumatic fever is established on the basis of identification of major and minor clinical manifestations of the disease, as detailed by the Jones criteria. They were initially published by a physician Thomas Duckett Jones in 1944, and have been revised over the years by the American Heart Association.

Numerous interpretations of these criteria exist, and guidelines can also vary in different settings, most notably in areas where acute rheumatic fever is endemic. The latest revision of the Jones criteria was published by the World Health Organization (WHO) in 2004, also known as modified Jones criteria.

Evidence of a recent streptococcal infection with at least two major manifestations, or one major and two minor manifestations present, are necessary in order to establish the diagnosis of a primary episode of acute rheumatic fever. These criteria can be really helpful, as differential diagnosis can be extensive due to the lack of specificity.

Five manifestations are considered major manifestations of acute rheumatic fever: carditis, migratory polyarthritis, Sydenham’s chorea, erythema marginatum, and subcutaneous nodules. The minor manifestations are arthralgias, fever, elevated acute-phase reactants and first degree heart block.

It should be emphasized that the principal use of these diagnostic criteria is to help in the identification of rheumatic fever. However, physicians maintain the right to make a diagnosis of this condition merely on the basis of clinical judgment, even if the modified criteria are not completely satisfied.

Laboratory studies

Acute phase reactants are useful in recognizing acute rheumatic fever and also to exclude other diseases. Certain studies suggest that C-reactive protein and erythrocyte sedimentation rates are commonly elevated in patients with confirmed rheumatic fever (excluding chorea), therefore are extremely helpful in monitoring inflammatory activity.

Laboratory evidence of an inflammation and a preceding streptococcal infection should be documented – either by demonstration of Streptococcus pyogenes in the throat by culture or using streptococcal antibody tests. Rising titers of antistreptolysin O (ASO) occur in more than 80% of patients with acute pharyngitis.

Prolonged PR interval relative to heart rate on electrocardiogram represents a nonspecific finding, which is found in more than one third of the patients. Low-voltage QRS complexes and changes of ST segment are sometimes found in the presence of pericarditis and pericardial effusion.

Cardiac scanning scintigraphy has been shown to be a reliable technique to distinguish acute from chronic, inactive rheumatic heart disease, whereas endomyocardial biopsy should only be limited to clinical investigation due to its invasiveness. The role of echocadiography to diagnose valvulitis without auscultatory findings has been debated.

Differential diagnosis

Several diseases should be considered when evaluating a patient with suspected rheumatic fever. Juvenile rheumatoid arthritis and other connective tissue diseases should be excluded, which is often possible as the articular involvement in juvenile rheumatoid arthritis usually lasts longer when compared to rheumatic fever.

Furthermore, systemic lupus erythematosus shares certain similarities with acute rheumatic fever (most notably arthralgia and transient arthritis). In addition, some cases of chorea are mild or atypical and may be confused with motor tics or the involuntary jerks of Gilles de la Tourette syndrome.