Rheumatic Fever (RF) – Diagnosis, Tests | Role of Echocardiography in RF
RHEUMATIC FEVER
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Last Updated : 10/1/2014
N C Joshi
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Role of echocardiography
Echocardiography is the only new diagnostic tool, which significantly contributes in confirming the presence of rheumatic carditis.

Initially echocardiography was used to differentiate the murmur of mitral regurgitation from systolic murmur caused by VSD, obstructive cardiomyopathy and mitral valve prolapse. It is now established that more than leaflet edema, the mitral annular dilation and secondary chordal elongation permits the apical portion of the anterior leaflet to prolapse back into the left atrium resulting in characteristic jet of regurgitant flow that passes over the posterior leaflet striking on posterior left-atrial wall.

Recent experience suggests that silent mitral regurgitation can be demonstrated by doppler evaluation in patients presenting with isolated rheumatic polyarthritis. Silent but pathologic mitral regurgitation that cannot be heard can be differentiated from physiologic if:
- Regurgitant flow is holosystolic
- Regurgitant flow should extend back to left-atrial wall
- Regurgitant flow should have mosaic pattern on color flow
- Regurgitant flow should be confirmed in more than one plane

There now appears to be enough experience to add echocardiographic demonstration of silent-valve regurgitation as an additional minor manifestation. It is also important to demonstrate this echocardiographic evidence of pathologic regurgitation in patients presenting with polyarthritis to decide about future penicillin prophylaxis.

Test for presence of rheumatic activity
Erythrocyte sedimentation rate
The elevation of ESR is due to increase in plasma fibrinogen secondary to inflammation. The magnitude of elevation of ESR is often directly proportional to the severity of the disease except in patients with heart failure whose liver may not produce enough fibrinogen.

Elevation of ESR is fairly good index of rheumatic activity. ESR remains elevated for about 4-8 weeks and it may remain high in severe carditis. Also, it may remain high longer in presence of anemia. ESR is useful in deciding how long a child should remain in bed or when to modify suppressive therapy.

C-reactive protein
It is not usually present in blood. It appears promptly in the course of any inflammatory reaction. It becomes normal much more readily than ESR and is a helpful adjunct in proving rheumatic activity because of its transient nature and rapid disappearance from blood. ESR is preferable to CRP especially for the follow up of rheumatic activity. CRP is not influenced by anemia or CHF so in the presence of other criteria and normal ESR, CRP is a good indication of rheumatic process. But in the absence of other criteria, normal ESR and elevated CRP suggest non-rheumatic etiology.

Leukocyte changes are of little help in rheumatic fever due to its variability.

Electrocardiogram in rheumatic fever
The most characteristic feature in acute rheumatic fever is conduction disturbances most commonly in the form of 1st degree heart block (a prolonged PR interval) which occurs in 24 - 40%. Dr. Jones in 1944 recommended repeat tracings to demonstrate a variation in atrioventricular conduction which is more valuable. The PR interval usually returns to normal after the disease becomes inactive and it can occur with or without carditis. In acute rheumatic pericarditis, ST elevation or inversion is present.

Diagnosis
The diagnosis of rheumatic fever in the presence of characteristic clinical and laboratory findings is straightforward in the majority cases. In clinical practice, however many borderline cases are encountered leading to over diagnosis or misdiagnosis and unnecessary treatment and precautions, which can be harmful. The Jones criteria originally diagnosed and subsequently revised in 1965 are useful guides to the diagnosis of rheumatic fever in most cases. According to Jones criteria, 1 major and 2 minor or 2 major criteria plus evidence of preceding streptococcal infection are required to establish the diagnosis of rheumatic fever.

The shortcomings of Jones criteria are as follows:
- Mild attack of rheumatic fever may not meet the criteria
- Other clinical pictures such as those of rheumatoid arthritis may at times meet the criteria
- Subcutaneous nodules and erythema marginatum although diagnostic are quite rare and secondary in importance and alone neither one can serve as a fully convincing evidence for the disease. The inclusion of these criteria as major manifestations may be confusing particularly to students and it is preferable to designate them as secondary major manifestation.
- Arthralgia is an extremely common prodromal sign in almost all patients who develop carditis. If carditis develops early, there is no diagnostic problem but at least in 25% of patients who develop carditis; arthralgia and low-grade fever are present few weeks prior. In a retrospective study of patients with carditis, at least one third were found to have a history of arthralgic episodes before diagnosis of rheumatic fever was made. It is possible that such cases have had mild attacks of rheumatic fever, which have escaped attention and have developed carditis in subsequent attacks. It is well known that attacks of rheumatic fever resemble one another but this observation was based on cases in whom the first attack had been diagnosed. No information is as yet available to indicate that major attacks of rheumatic fever may at times be preceded by minor attacks. Our data at B.J Wadia hospital suggest that such a state may indeed exist and a different approach to the Jones criteria may be needed.

Due to diversity of clinical manifestations of rheumatic fever one can parallel the spectrum of the diseases to a shooting target. When the diseases manifest itself fully it hits the center of the board and the manifestations are carditis, polyarthritis and chorea. Simultaneously with the first two, subcutaneous nodules and erythema marginatum may appear, both of which are of secondary importance. The disease may hit the periphery of the target. It is the periphery that does not contain the major manifestation. On future attacks, the center may again be hit. Most important is recognizing the patients in the periphery and protecting them from future full blown attacks of the diseases. The patient in the periphery can be divided in three groups:

- Children who complain of significant arthralgia without a high ASO titre or ESR. Such patients should follow all the instructions for full protection against streptococcal infections must be given.

- Children with arthralgia with raised ASO titre and normal ESR. These patients may be in recovery phase of mild rheumatic fever. They must again be followed as the potential risks.

- Children with arthralgia with high ASO titre and ESR. Such patients probably suffered from mild rheumatic fever. Prophylaxis and even a short course of aspirin treatment are indicated.

All 3 groups must have throat culture and should be treated accordingly. If prophylaxis is decided to be given- a period of 6 months to one year would suffice followed by insuring further protection against streptococcal infections.



Contributor Information and Disclosures

N C Joshi
Consultant Pediatrician, Nanavati Hospital, Mumbai, India


First Created : 1/24/2001
Last Updated : 10/1/2014

References

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