Causes of infectious and inflammatory cardiac involvement
Pathologies of the heart muscle and its membranes are often infectious or toxic-metabolic in nature.
Among infectious agents, the leading role is played by:
- Viruses: Coxsackie viruses, adenoviruses, and ECHO viruses can cause latent inflammation that transforms into cardiomyopathy.
- Bacteria: The spectrum of pathogens is extremely broad. These include staphylococci, meningococci, pneumococci (often as a complication of pneumonia), streptococci, salmonellae, and chlamydiae. Mycobacterium tuberculosis also remains relevant, especially in the development of specific pericarditis.
- Fungi and other agents: Aspergillus, blastomycetes, coccidioids, and rickettsiae.
In addition to direct infection, cardiac involvement can develop secondary to other conditions. Non-infectious factors include oncological processes (paraneoplastic reactions, metastases), severe metabolic disorders (uremia in renal failure, myxedema), and systemic connective tissue diseases (rheumatoid arthritis, systemic lupus erythematosus). Coronary artery disease is highlighted separately: inflammation can accompany acute myocardial infarction or manifest in the late period as Dressler's syndrome (post-myocardial infarction polyserositis).
Diagnostic criteria for inflammation (Major and minor)
To assess specific target-organ damage (e.g., in rheumatic fever, which often accompanies infectious processes), manifestations are divided into major and minor criteria.
Major (specific) criteria:
- Carditis — direct inflammation of the heart layers.
- Polyarthritis — involvement predominantly of large joints.
- Chorea — specific involvement of the nervous system.
- Erythema marginatum — characteristic skin manifestations.
- Subcutaneous nodules — formation of firm rheumatic nodules.
Minor (non-specific) criteria indicate the general reactivity of the body:
- Clinical: persistent fever and arthralgia (joint pain without visible signs of inflammation, which must be differentiated from true polyarthritis).
- Laboratory markers of the acute phase: elevated erythrocyte sedimentation rate (ESR), increased C-reactive protein (CRP) levels.
- Instrumental: ECG records prolongation of the P-Q interval, indicating impaired atrioventricular conduction.
Impact on the valvular apparatus: Tricuspid regurgitation
Inflammatory processes, including infective endocarditis, directly damage valve structures. One presentation is primary (organic) tricuspid valve regurgitation. In addition to infective endocarditis, it can be caused by rheumatic fever, carcinoid syndrome, and chest trauma.
The essence of the pathology is that the valve leaflets do not close completely during the contraction (systole) of the right ventricle. Consequently, a portion of the blood regurgitates back into the right atrium.
Interestingly, hemodynamics are somewhat less severely impaired here than in left-sided valve defects. Pressure in the pulmonary circulation is lower, allowing blood to flow more easily into the pulmonary artery, and the regurgitant volume is relatively small. However, when congestive failure develops, the clinical picture changes: pulmonary congestion may be absent, but systemic venous congestion appears early and significantly (jugular venous distension, positive venous pulse, epigastric pulsation).
Auscultation reveals a systolic murmur at the left sternal border. An important diagnostic marker is Rivero-Carvallo's sign: the murmur intensifies during inspiration as venous return to the right heart increases, augmenting the regurgitant volume.
Impact on the valvular apparatus: Mitral stenosis
Involvement of the left heart produces a different clinical picture. The main symptoms are detected by auscultation at the cardiac apex:
- The first heart sound (S1) becomes accentuated and "snapping" due to leaflet thickening.
- The second heart sound (S2) is accompanied by an additional sound — the opening snap of the mitral valve (opening snap).
- A diastolic murmur with characteristic presystolic accentuation is heard (if sinus rhythm is preserved).
Palpation may reveal a diastolic thrill known as a "cat's purr". The patient's appearance is also specific: facies mitralis develops (youthful appearance with cyanotic malar flush). Instrumental tests (ECG and X-ray) reveal signs of left atrial overload and enlargement (P-mitrale), right ventricular hypertrophy, and signs of pulmonary hypertension (accentuation of S2 over the pulmonary artery).
Diffuse myocardial involvement and heart failure
Prolonged exposure to exogenous, toxic, or infectious factors leads to the death of functioning cardiomyocytes, resulting in diffuse myocardial injury.
The process is accompanied by dilatation (pathological enlargement) of the cardiac chambers. Consequently, myocardial contractility drops sharply, and cardiac output decreases. Systolic and diastolic dysfunction of both ventricles develops. The clinical outcome of this relentlessly progressive process is severe congestive chronic heart failure. Such a diagnosis is often made by exclusion, once other causes of heart disease and pulmonary hypertension have been ruled out.
Briefly: answers to topical questions
What are the specific pathophysiological mechanisms underlying chronic heart failure in diffuse myocardial involvement?
The pathophysiological mechanisms of chronic heart failure in diffuse myocardial injury include the following sequence:
- Cardiomyocyte death — exposure to exogenous factors causes the death of fully functioning cardiomyocytes.
- Cardiac chamber enlargement — compensatory and pathological enlargement of the heart chambers develops, morphologically corresponding to ventricular dilatation.
- Reduced contractility — impaired myocardial contractility occurs, leading to a drop in cardiac output.
- Ventricular dysfunction — systolic and diastolic dysfunction of both ventricles develops.
- Outcome — chronic, congestive heart failure is established.
What specific echocardiographic (EchoCG) findings are characteristic of infective endocarditis?
The echocardiographic picture in infective endocarditis includes the direct visualization of vegetations, assessment of the valvular apparatus, and signs of hemodynamic overload.
- Vegetations — visualization of vegetations (evaluating their large size, mobility, and echogenicity).
- Valvular regurgitation — detection of severe mitral and aortic regurgitation, as well as valve perforation.
- Periannular complications — visualization of abscesses, fistulae, and perivalvular extension of infection.
- Hemodynamic disturbances — premature closure of the mitral valve, low left ventricular ejection fraction, and pulmonary hypertension.
- Prosthetic valves — prosthetic valve dysfunction.
Mnemonic for major criteria: Carditis, Polyarthritis, Chorea, Erythema marginatum, Subcutaneous nodules.
Class and exam questions
What is Rivero-Carvallo's sign?
This is an auscultatory phenomenon: intensification of the systolic murmur during inspiration in patients with tricuspid regurgitation.
What is the difference between primary and secondary tricuspid regurgitation?
Primary is caused by organic leaflet damage (e.g., in infective endocarditis). Secondary occurs functionally due to dilation of the right ventricle and the fibrous annulus in the setting of pulmonary hypertension.
What ECG changes are characteristic of mitral valve disease?
The ECG records signs of left atrial overload (P-mitrale), right ventricular hypertrophy, and rightward axis deviation.
What else to study on this topic
- Pathogenesis of dilated myocardial injury
- Differential diagnosis of mitral stenosis
- Instrumental assessment of the venous pulse (phlebogram)
- Pathophysiology of pulmonary hypertension in left-sided heart defects
- Specifics of fungal and parasitic heart diseases
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