Rheumatic Heart Diseases

Introduction and Epidemiology

• Rheumatic heart disease (RHD) is the most common cause of acquired, nonatherosclerotic heart disease globally, representing the most important sequela of acute rheumatic fever (ARF).
• It accounts for a significant proportion of childhood morbidity and mortality in developing nations, with an estimated global prevalence of 40.5 million cases as of 2019.
• The annual incidence of ARF ranges from 5 to 50 per 100,000 children globally, with the highest incidence rates (>10 per 100,000) documented in Eastern Europe, the Middle East, Asia, Australasia, and sub-Saharan Africa.
• The incidence of the initial ARF episode typically peaks in children between 5 and 15 years of age; initial episodes are exceedingly rare before 3 years or after 30 years of age.
• While both sexes are equally affected by ARF, RHD demonstrates a marked female preponderance, especially after the age of 15, likely due to a multifactorial interaction between biological, autoimmune, and environmental factors.
• Recognized predisposing environmental risk factors include poor socioeconomic conditions, unhygienic living environments, and overcrowded households which facilitate the transmission of streptococcal pharyngitis.
• RHD prevalence typically peaks in early adulthood, between 20 and 44 years of age, reflecting the cumulative cardiovascular damage from recurrent ARF episodes throughout childhood and adolescence.

Etiopathogenesis and Genetics

• ARF is an immunological disorder initiated by untreated pharyngeal infection with Group A beta-hemolytic Streptococcus pyogenes (GAS).
• A latent period of 10 days to several weeks exists between the initial streptococcal sore throat and the onset of ARF, underscoring the immune-mediated rather than directly infectious nature of the disease.
• The core pathophysiological mechanism is molecular mimicry; GAS-derived M protein and carbohydrate antigens (such as N-acetyl-beta-D-glucosamine) share antigenic T cell and B cell epitopes with human host tissues, specifically cardiac myosin and laminin on the heart valves.
• Following phagocytosis of GAS by dendritic cells and macrophages, antigen presentation activates CD4+ T cells and induces the production of cross-reactive IgM and IgG antibodies.
• These cross-reactive antibodies and T cells inappropriately target host tissues, leading to inflammation in the heart (carditis), brain (chorea), joints (arthritis), and skin.
• In the heart, the initial humoral immune response damages the valvular endothelium, causing the expression of vascular cell adhesion molecule 1 (VCAM-1), which facilitates the recruitment and infiltration of CD4+, CD8+ T lymphocytes, and macrophages into the connective tissue core of the valve.
• This intense inflammatory cascade initiates neovascularization of the valve substance and permanent fibrosis; notably, only the heart valves suffer permanent damage, whereas inflammation in the joints, brain, and pericardium typically resolves without residua.
• Genetic susceptibility plays a critical role, as only 3% to 6% of individuals with GAS pharyngitis develop ARF; monozygotic twins exhibit significantly higher disease concordance than dizygotic twins.
• Genome-wide association studies (GWAS) and candidate gene studies have identified susceptibility loci in immune-regulating genes such as TGFB1, IL1B, and the HLA-DQA1 to HLA-DQB1 region, which influence antigen presentation and host immune reactivity.

Clinical Manifestations and the Jones Criteria

• The diagnosis of ARF is established using the revised Jones Criteria (American Heart Association/World Heart Federation), which stratifies populations into low-risk versus moderate/high-risk categories based on the background prevalence of RHD.
• For the first episode of ARF, the diagnosis requires the presence of two major criteria OR one major and two minor criteria, absolutely coupled with essential evidence of a preceding GAS infection.

Revised Jones Criteria for Acute Rheumatic Fever

Specific Major Manifestations

• Carditis: Occurs in up to 90% of patients and is considered a true pancarditis involving the endocardium, myocardium, and pericardium. Valvulitis (endocarditis) is universal; the mitral valve is almost always involved, with or without the aortic valve. Severe acute mitral regurgitation can cause acute left ventricular volume overload and congestive heart failure.
• Arthritis: An early manifestation occurring in 30% to 80% of patients. It is classically a migratory, asymmetrical polyarthritis involving large joints (knees, ankles, elbows, wrists) characterized by severe pain, swelling, and redness that exquisitely responds to salicylates within 48 hours.
• Sydenham's Chorea: A late neurological manifestation appearing 1 to 6 months post-infection in 7% to 28% of cases. It manifests as semi-purposeful, involuntary, irregular movements, muscular incoordination, and emotional lability; it is generally self-limiting over 2 to 6 weeks.
• Erythema Marginatum: A rare, early cutaneous finding presenting as faintly reddish, non-pruritic, non-raised macules that extend centrifugally with central clearing to form serpiginous outlines, predominantly located on the trunk and proximal limbs.
• Subcutaneous Nodules: A late manifestation consisting of firm, painless, pinhead-to-almond-sized nodules located over bony prominences (elbows, shins, occiput, spine); they are strongly associated with the presence of severe carditis.

Valvular Pathology, Hemodynamics, and Clinical Findings

Mitral Regurgitation (MR)

• Pathophysiology: MR is the most common valvular lesion in both acute and chronic RHD. In the acute phase, annular dilation, chordal elongation, and prolapse of the anterior leaflet result in a failure of coaptation. The left atrium and left ventricle dilate to accommodate the volume overload generated by systolic backflow.
• Auscultation: A soft, blowing, pansystolic murmur is best heard at the cardiac apex and frequently radiates to the axilla and the left sternal border. The first heart sound (S1) is typically soft, and the second heart sound (S2) is widely and variably split. A protodiastolic third heart sound (S3) gallop followed by a short, low-pitched mid-diastolic murmur (Carey Coombs murmur) indicates increased transmitral flow due to severe regurgitation.
• Electrocardiogram (ECG): Shows signs of left atrial enlargement (broad, biphasic P waves) and left ventricular hypertrophy (LVH); sinus tachycardia is commonly present in the acute inflammatory phase.
• Chest Radiograph (CXR): Demonstrates cardiomegaly driven by prominent left atrial and left ventricular shadows. With acute decompensation, signs of pulmonary venous congestion and interstitial pulmonary edema may be present.
• Echocardiography: Transthoracic echocardiography reveals annular dilation, elongation of chordae, and nodular thickening restricted to the leaflet tips. A characteristic anterior leaflet prolapse or pseudoprolapse is visualized, accompanied by a high-velocity regurgitant color Doppler jet in the left atrium.
• Cardiac Catheterization: Left ventriculography visually outlines the regurgitant flow of contrast into the left atrium during systole; elevated pulmonary capillary wedge pressures with prominent 'V' waves are diagnostic of significant MR.

Mitral Stenosis (MS)

• Pathophysiology: MS is a late, chronic complication of RHD, rarely seen in young children but presenting after a latent period of 10 or more years. It is caused by progressive fibrosis of the mitral ring, fusion of the commissures, and contracture and shortening of the leaflets and subvalvular chordae tendineae. This mechanical obstruction impedes left ventricular filling, causing massive left atrial enlargement and subsequent pulmonary arterial hypertension.
• Auscultation: A loud, snapping first heart sound (S1) is followed by an early diastolic opening snap and a low-pitched, rumbling mid-diastolic murmur with presystolic accentuation best heard at the apex with the bell.
• Electrocardiogram (ECG): Demonstrates severe left atrial enlargement (P-mitrale: wide, notched P waves in lead II) and varying degrees of right ventricular hypertrophy (RVH) and right axis deviation secondary to pulmonary hypertension. Atrial fibrillation is a common late complication.
• Chest Radiograph (CXR): Reveals a straightened left heart border due to an enlarged left atrial appendage and main pulmonary artery, a double right heart border indicating left atrial enlargement, and pulmonary venous hypertension (Kerley B lines) with relative sparing of the left ventricular size.
• Echocardiography: Demonstrates severe restriction of leaflet motion, commissural fusion, and the classic "hockey-stick" or "dog-leg" diastolic deformity of the anterior mitral leaflet. Continuous-wave Doppler calculates the elevated transmitral pressure gradient and quantifies the reduced valve area.
• Cardiac Catheterization: Simultaneous measurement of pulmonary capillary wedge pressure (or direct left atrial pressure) and left ventricular end-diastolic pressure calculates the diastolic transmitral gradient.

Aortic Regurgitation (AR)

• Pathophysiology: Isolated AR is rare and typically coexists with mitral valve disease. In the acute phase, inflammation causes irregular focal leaflet thickening and coaptation defects; in the chronic phase, progressive fibrosis and cusp retraction result in severe regurgitation, leading to extreme left ventricular volume overload, massive LV dilation, and increased stroke volume.
• Auscultation: A high-pitched, early decrescendo diastolic murmur is heard optimally at the mid-to-upper left sternal border. A widened pulse pressure is universally present. An apical rumbling diastolic murmur (Austin-Flint murmur) may be heard due to the regurgitant jet impinging on the anterior mitral leaflet, mimicking MS.
• Electrocardiogram (ECG): Shows marked left ventricular hypertrophy (tall R waves in V5-V6, deep S waves in V1) frequently accompanied by a volume-overload strain pattern consisting of ST-segment depression and T-wave inversion in the lateral precordial leads.
• Chest Radiograph (CXR): Demonstrates a massively dilated left ventricle extending downward and outward, accompanied by prominent dilation of the ascending aorta.
• Echocardiography: Parasternal long-axis views demonstrate a dilated left ventricle, focal aortic leaflet thickening with restricted excursion, and high-frequency diastolic fluttering of the anterior mitral leaflet caused by the regurgitant jet. Color Doppler localizes and quantifies the severity of the diastolic regurgitant flow into the LV outflow tract.
• Cardiac Catheterization: Aortography definitively visualizes the regurgitation of contrast from the aortic root back into the left ventricular cavity during diastole.

Tricuspid Regurgitation (TR)

• Pathophysiology: Primary rheumatic involvement of the tricuspid valve is uncommon; TR is usually secondary to severe right ventricular dilation and tricuspid annular stretching caused by left-sided valvular disease and severe pulmonary hypertension.
• Auscultation: A harsh, blowing holosystolic murmur is audible at the lower left sternal border; classically, the intensity of this murmur increases during inspiration (Carvallo's sign) due to augmented venous return.
• Electrocardiogram (ECG): Frequently shows right atrial enlargement (tall, peaked P-pulmonale) and right ventricular hypertrophy secondary to the underlying pulmonary hypertension.
• Chest Radiograph (CXR): Reveals extreme cardiomegaly, largely driven by massive right atrial and right ventricular enlargement, often resulting in a globular cardiac silhouette.
• Echocardiography: Confirms the massive dilation of the right heart chambers and detects the severe tricuspid regurgitant jet via color Doppler, which allows for the accurate estimation of right ventricular systolic pressures.

General Diagnostic Investigations

Laboratory Studies

• Acute Phase Reactants: Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are universally elevated during an episode of ARF and serve as critical minor Jones criteria; CRP normalizes rapidly with anti-inflammatory therapy, while ESR may remain elevated for 4 to 10 weeks.
• Streptococcal Antibodies: An elevated or rising Antistreptolysin O (ASO) titer provides essential diagnostic confirmation of preceding GAS infection. A significantly rising titer on serial sampling is the most robust immunological evidence.
• Throat Culture: Less commonly positive at the time of ARF presentation, but a positive throat swab for GAS remains an essential confirming criterion.

Advanced Echocardiography for Subclinical Carditis

• Echocardiography with Doppler interrogation is mandated for all patients with suspected ARF, as it identifies subclinical carditis in up to 18% of patients lacking auscultatory findings.
• Specific criteria for pathological subclinical mitral regurgitation include: a color Doppler jet seen in at least two views, a jet length $\ge$ 2 cm, a peak velocity >3 m/sec, and a pan-systolic duration in at least one envelope.
• Specific criteria for pathological subclinical aortic regurgitation include: a jet length $\ge$ 1 cm in at least two views, a peak velocity >3 m/sec, and a pan-diastolic duration.

Management of Acute Rheumatic Fever and RHD

Primary and Secondary Prevention

• Primary Prevention: Timely administration of antibiotics (such as a 10-day course of oral phenoxymethylpenicillin or a single intramuscular injection of benzathine benzylpenicillin) for symptomatic GAS pharyngitis prevents the initial development of ARF.
• Secondary Prevention: Essential to halt the progression of RHD by preventing recurrent ARF episodes. It involves the administration of continuous antibiotic prophylaxis, typically a single intramuscular injection of Benzathine Penicillin G (1.2 million units for >30 kg; 600,000 units for <30 kg) every 3 to 4 weeks.

Recommended Duration of Secondary Prophylaxis

Medical Management of the Acute Episode

• Eradication of GAS: A therapeutic dose of penicillin (or azithromycin for allergic patients) must be administered upon diagnosis regardless of throat culture results to eradicate any residual carriage.
• Anti-inflammatory Therapy: For isolated arthritis and fever, high-dose aspirin (80-120 mg/kg/day in divided doses) is the drug of choice, demonstrating dramatic and rapid symptom relief.
• Corticosteroids: For patients presenting with severe carditis accompanied by cardiomegaly or congestive heart failure, systemic corticosteroids (e.g., Prednisolone 2 mg/kg/day) are strongly preferred over aspirin. Steroids rapidly suppress severe inflammation, alleviate pericardial friction rubs, and resolve subcutaneous nodules, though they have not been definitively proven to alter long-term valvular scarring.
• Management of Heart Failure: Patients presenting with acute left ventricular failure secondary to severe regurgitation require immediate bed rest, fluid restriction, and conventional decongestive therapy utilizing diuretics (e.g., furosemide). The utilization of afterload-reducing agents like Angiotensin-Converting Enzyme (ACE) inhibitors is controversial in the acute setting but is widely used to decrease regurgitant fraction in severe MR and AR. Digoxin and beta-blockers may be cautiously considered depending on ventricular function and clinical stability.
• Chorea Management: Sydenham's chorea is typically self-limiting. Management is largely supportive, involving a quiet environment and reassurance. For severe, debilitating movements, medications such as haloperidol, diazepam, pimozide, or carbamazepine are highly effective.

Long-term Management of Chronic RHD

• Serial echocardiographic surveillance is mandatory to monitor valve morphology, the progression of stenosis or regurgitation, right ventricular pressures, and biventricular systolic function.
• Anticoagulation: Chronic RHD with significant mitral stenosis frequently precipitates atrial fibrillation and profound left atrial dilation, establishing a massive risk for thromboembolic stroke. Lifelong anticoagulation with Vitamin K Antagonists (e.g., Warfarin) is absolutely indicated for patients with RHD complicated by atrial fibrillation, prior embolic events, or the presence of a left atrial thrombus.
• Infective Endocarditis Prophylaxis: Damaged, scarred rheumatic valves are highly susceptible to bacterial seeding. Patients with established RHD or prosthetic heart valves must receive antibiotic prophylaxis (e.g., Amoxicillin) prior to any dental or invasive procedures expected to provoke transient bacteremia.

Interventional and Surgical Management

• Structural intervention is definitively indicated for patients with severe, symptomatic valvular disease, or asymptomatic patients demonstrating progressive left ventricular dilation, declining systolic function, or the onset of severe pulmonary hypertension.
• Percutaneous Mitral Balloon Commissurotomy (PMBC): The procedure of choice for symptomatic patients with severe, pliable rheumatic mitral stenosis (valve area <1.5 cm²) provided there is no left atrial thrombus and no more than mild (grade 1+) associated mitral regurgitation.
• Surgical Valve Repair vs. Replacement: For severe mitral regurgitation, surgical mitral valve repair (including annuloplasty) is heavily favored over replacement in the pediatric population to circumvent the lifelong morbidities of mechanical valves, specifically the requisite strict anticoagulation monitoring and the inevitability of outgrowing the prosthetic valve.
• Valve Replacement: In cases where extensive calcification, severe subvalvular fibrosis, or complex mixed stenosis-regurgitation lesions render the valve unrepairable, surgical replacement with a mechanical or bioprosthetic valve is unavoidable. Mechanical valves mandate lifelong, rigorous systemic anticoagulation, while bioprosthetic valves carry a markedly increased risk of early structural degeneration and failure in young patients.

Complications and Prognosis

• Without strict adherence to secondary penicillin prophylaxis, recurrent ARF episodes uniformly lead to progressive and cumulative valvular destruction.
• Severe chronic RHD commonly results in progressive biventricular congestive heart failure and profound exercise intolerance, severely curtailing life expectancy.
• Structural dilation of the left atrium secondary to severe MR or MS invariably predisposes the patient to the development of highly symptomatic atrial fibrillation and flutter.
• The combination of blood stasis in a fibrillating, massively dilated left atrium and an inflamed endocardial surface creates a highly thrombogenic milieu, leading to frequent, devastating systemic thromboembolic events such as cerebrovascular strokes and mesenteric ischemia.