Rheumatic Heart Disease

Rheumatic heart disease, typically seen in developing countries among children and young adults, is characterised by chronic valvular inflammation secondary to recurrent Group A strep. infection, Aschoff bodies pathologically, and mitral regurgitation or stenosis on echocardiography.

Description

Rheumatic heart disease (RHD) is a chronic heart condition resulting from rheumatic fever, caused by Group A streptococcal infection. Acute rheumatic fever causes pancarditis, which affects the valve leafets, pericardium, epicardium, myocardium, and endocardium, leading to complications such as valve stenosis, regurgitation, or heart failure. The most common valve lesion is mitral regurgitation.

Pathogenesis

RHD results from an autoimmune reaction following a group A beta-hemolytic streptococcal infection. This reaction is caused by molecular mimicry between the streptococcal M protein and proteins in the human heart, leading to immune-mediated damage to cardiac tissues. Rheumatic valve disease may first become apparent years or decades after initial infection. Most commonly affects mitral valve, followed by aortic and tricuspid valve.

Epidemiology, Risk Factors & Associations

RHD is most common in low-income populations, with a worldwide prevalence of approximately 33 million people and responsible for around 275,000 deaths annually. Recurrent untreated streptococcal pharyngitis (70%) and substandard living conditions (over 80% of cases) are significant risk factors. Overcrowding, poor sanitation, and limited access to healthcare contribute to the disease’s propagation.

Clinical Features

• Mitral regurgitation which can lead to symptoms of heart failure (20% of cases).
  • Mitral stenosis is the most common (40%) sequela in later stages, presenting with exertional dyspnoea, palpitations, and fatigue.
• Aortic stenosis and regurgitation are less common (10%) but may coexist.
• Pancarditis, presenting with heart murmurs, tachycardia, pericardial rub, and heart failure signs, occurs in 50% of cases.
• Sydenham’s chorea, a neurological manifestation marked by sudden, purposeless movements, occurs in 10-20% of cases.

Complications

• Chronic rheumatic heart disease: results in permanent valve damage, leading to valve stenosis or regurgitation.
• Atrial fibrillation: occurs in 30-40% of patients with mitral valve involvement.
• Heart failure: late complication seen in 20% of individuals.
• Infective endocarditis: a risk in those with valve damage.
• Fibrinous Pericarditis
• Stroke: secondary to embolism from valvular lesions or atrial fibrillation.

Pathological Features

Macroscopic

The typical morphological changes include valve leaflet thickening, calcification and fusion, commissural fusion and shortening, and chordal fusion and shortening. Mitral valve may demonstrate fish mouth or button hole configuration.

Microscopic:

• Aschoff bodies (characteristic): focal, overactive inflammatory lesions found in the heart muscle.
• Anitschkow cells or “caterpillar cells”: large histiocytes with slender, wavy nuclei.
• Fibrinoid necrosis with verrucous endocarditis leading to valve thickening, deformity, and stenosis.

Radiological Features

General Features

• Cardiomegaly may be present with a slightly enlarged cardiothoracic ratio.
• Dilated left atrial appendage and left atrium are often noted.
• Right-sided double-density sign on frontal radiograph due to the appearance of enlarged left atrium is a common finding.
• Calcification of anterior and posterior leaflets of mitral valve (not annular calcification) can be seen.
• Pancarditis with valve insufficiency leading to acute congestive heart failure (CHF) – interstitial pulmonary oedema or upper lobe pulmonary venous redistribution.
• Convex left atrial appendage segment, right double density, and pulmonary venous redistribution are classic findings of rheumatic mitral valve disease on radiograph.
• Convex pulmonary artery segment and large central pulmonary arteries may develop due to back pressure in chronic rheumatic mitral valve disease.
• In echocardiography, the diastolic doming of the mitral valve is a classic sign of rheumatic mitral stenosis.

CT

• NECT: May show an enlarged left atrium and the calcification of anterior and posterior leaflets of the mitral valve. Calcified left atrial wall may also be seen. Extensive calcifications may result in a “porcelain heart” appearance.
• Cardiac-gated CTA: May show thickening and incomplete opening of mitral valve leaflets in diastole. It allows assessment of additional valvular involvement, including the aortic and tricuspid valves, and may demonstrate left atrial appendage thrombus.
• Delayed: Can help to distinguish between a true thrombus and slow mixing of contrast in the left atrium and left atrial appendage.

MRI

• MR cine imaging using Cine SSFP images demonstrate valvular regurgitation and/or stenosis. This can show diastolic doming of the mitral valve, indicating stenosis.
• Mitral regurgitation can be quantified using phase-contrast MR techniques.
• Late gadolinium enhancement (LGE) may reveal abnormal enhancement in the left atrial wall, pericardial enhancement due to inflammation, and myocarditis in the acute phase, progressing to dilated cardiomyopathy.

Echo

• Doppler echocardiography is used to calculate pressure half-time valve area and transvalvular gradient.
• Colour Doppler can show both mitral stenosis and mitral regurgitation.
• 3D echocardiography allows for accurate planimetry of valve area and is emerging as a crucial modality in RHD assessment.
• Stress echocardiography is utilized if there is discordance between findings at rest and clinical findings with exercise.
• Left atrial enlargement and valvular leaflet thickening, diastolic doming, and incomplete opening of valve are common findings.
• Other valve involvement may be demonstrated.

Additional Considerations

• Pericarditis: Although not typically a direct consequence of RHD, pericarditis can occasionally be seen in association with severe carditis. It can be detected on echocardiography as a circumferential fluid collection around the heart, and may be associated with signs of inflammation or constrictive physiology.

Grading and Staging

There is no universally accepted grading or staging system. Diagnosis is based on a combination of clinical history, examination, and echocardiography findings.

Prognosis

The prognosis for RHD varies depending on the severity of the valve disease and the presence of complications such as heart failure and atrial fibrillation.

Differential Diagnosis

• Infective endocarditis: Suggested by acute presentation with fever, positive blood cultures.
• Degenerative valve disease: More common in older adults, with gradual onset.
• Congenital heart disease: Typically presents earlier in life, often with associated congenital anomalies.

Management

• Antibiotic prophylaxis to prevent initial and recurrent streptococcal infection.
• Regular monitoring with echocardiography.
• Heart failure management with diuretics, ACE inhibitors, and beta-blockers.
• Anticoagulation for those with atrial fibrillation or high-risk features for thromboembolism.
• Surgical intervention for severe valve disease, either repair or replacement.
• Referral to a cardiologist for further management.