Endocarditis
### Endocarditis
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#### 1. Basic Disease Identification
- Name of the Disease: Endocarditis
- Synonyms: Infective Endocarditis (IE), Bacterial Endocarditis
- ICD-10/ICD-11 Code:
- ICD-10: I33 (Endocarditis)
- ICD-11: 4A00 (Infective endocarditis)
- Other Classifications:
- Acute vs Subacute Endocarditis: Classified based on the onset and progression of symptoms.
- Native Valve Endocarditis vs Prosthetic Valve Endocarditis: Based on whether the infection affects natural heart valves or prosthetic valves.
- Right-Sided vs Left-Sided Endocarditis: Depending on the location of infection within the heart.
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#### 2. Overview
- Brief Description:
Endocarditis is an infection of the endocardium, typically involving the heart valves, and is most commonly caused by bacteria. It is a serious condition that can lead to valve destruction, septic embolism, heart failure, and death if not treated promptly.
- Historical Background:
The recognition of infective endocarditis has evolved since the 19th century, with significant advances in diagnostic techniques such as echocardiography, blood cultures, and the use of antibiotics. Historically, the disease was often fatal before the advent of antibiotics.
- Epidemiology:
- Global Prevalence: Approximately 1.5-3 cases per 100,000 people annually.
- Age, Gender, Ethnicity Distribution: Most commonly affects individuals with underlying heart disease (valvular heart disease, congenital heart disease, prosthetic heart valves) and those who inject illicit drugs.
- Risk Factors: Poor dental hygiene, intravenous drug use, immunocompromised states, prosthetic valves, history of valvular heart disease, and indwelling medical devices.
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#### 3. Etiology (Causes)
- Primary Causes:
- Bacterial Infections: The most common cause of infective endocarditis is bacterial infection, with the most common pathogens being:
- Staphylococcus aureus (including methicillin-resistant Staphylococcus aureus [MRSA]) – particularly in intravenous drug users and prosthetic valve infections.
- Streptococcus viridans – the most common pathogen in subacute endocarditis, often affecting patients with pre-existing valvular heart disease.
- Enterococcus species – often seen in older adults and those with gastrointestinal or genitourinary procedures.
- Coagulase-negative staphylococci – common in prosthetic valve infections and catheter-associated endocarditis.
- Fungal infections: Such as Candida species, are seen in immunocompromised patients.
- Secondary Causes:
- Intravenous Drug Use: Increases the risk of infection, particularly right-sided endocarditis affecting the tricuspid valve.
- Dental Procedures: Dental work, particularly in patients with poor oral hygiene, can introduce bacteria into the bloodstream (bacteremia), leading to endocarditis in predisposed individuals.
- Rare Causes:
- Viruses: Rarely, viral infections such as Coxsackievirus and cytomegalovirus have been implicated in endocarditis, though these are less common.
- Mycotic Infections: Fungal endocarditis is more likely in immunocompromised individuals or those with indwelling devices.
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#### 4. Pathophysiology
- Mechanism of Disease:
- Bacteremia (the presence of bacteria in the blood) leads to bacterial seeding of the endocardium, where the microorganisms adhere to valve surfaces, particularly if the endocardium is already damaged or roughened (e.g., in the presence of valvular heart disease or prosthetic valves).
- The immune response generates inflammatory damage and leads to the formation of infective vegetations – clumps of bacteria, platelets, fibrin, and inflammatory cells – on the valve surfaces.
- Embolism: Pieces of these vegetations may break off and travel through the bloodstream, leading to septic emboli, which can lodge in distant organs (brain, kidneys, spleen, lungs).
- Involved Organs & Systems:
- Heart: The primary site of infection is the heart valves, but it can also involve the endocardium and the myocardium.
- Kidneys: Septic emboli can lodge in the renal vasculature, leading to renal infarctions or abscesses.
- Brain: Embolic strokes or brain abscesses may occur.
- Spleen and Lungs: Septic emboli can also affect the spleen (splenic infarction) and lungs (pulmonary emboli or abscesses).
- Biochemical Pathways:
- The immune response involves activation of the complement system and cytokine release, leading to inflammation and damage to surrounding tissues.
- Microbial Virulence Factors: Bacteria like Staphylococcus aureus produce toxins that can damage endothelial cells and promote bacterial adhesion.
- Pathogenesis Timeline:
The disease progression depends on the virulence of the infecting organism and the presence of predisposing heart conditions. Acute bacterial endocarditis can progress rapidly, while subacute endocarditis typically has a slower onset.
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#### 5. Clinical Features
- Signs and Symptoms:
- Fever: The most common presenting symptom.
- Heart murmur: New or changed murmurs due to valvular damage or vegetation.
- Signs of septic embolism:
- Splinter hemorrhages (small blood clots under the nails).
- Janeway lesions (non-tender erythematous macules on palms or soles).
- Osler's nodes (painful, raised lesions on fingers or toes).
- Roth spots (retinal hemorrhages).
- Fatigue, weight loss, and night sweats.
- Complications:
- Heart failure: Due to valve damage, particularly with acute endocarditis or chronic valvular destruction.
- Septic embolism: Leading to organ infarction (brain, kidney, spleen).
- Abscess formation: In the heart or elsewhere.
- Chronic renal failure: Due to embolic kidney infarcts.
- Septic shock: In cases of advanced or untreated infection.
- Disease-Specific:
- Acute Endocarditis: Rapid progression, often due to Staphylococcus aureus, with high mortality without prompt treatment.
- Subacute Endocarditis: Longer duration, often due to Streptococcus viridans, and may present with a more insidious onset.
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#### 6. Diagnostic Criteria
- Diagnostic Guidelines:
The diagnosis is made based on the modified Duke criteria, which combines clinical findings, microbiological evidence, and echocardiographic findings.
- Major criteria: Positive blood cultures (from at least two separate blood cultures), evidence of endocardial involvement on echocardiogram (e.g., vegetation, abscess).
- Minor criteria: Predisposing heart conditions, fever, vascular phenomena (e.g., emboli, Janeway lesions), immunologic phenomena (e.g., Osler's nodes, glomerulonephritis).
- Differential Diagnosis:
- Rheumatic heart disease: Can present similarly with valve involvement, but is associated with a history of rheumatic fever.
- Non-infective causes of endocardial lesions: Such as Libman-Sacks endocarditis in systemic lupus erythematosus (SLE).
- Laboratory Investigations:
- Blood cultures: Multiple sets, especially if fever is present.
- Complete blood count (CBC): Often shows leukocytosis, anemia, and elevated ESR/CRP.
- Renal function tests: To check for kidney involvement (e.g., septic emboli).
- Imaging Studies:
- Echocardiography (Transthoracic and Transesophageal): The gold standard for visualizing vegetations, valve involvement, and complications like abscesses.
- Chest X-ray: To rule out pulmonary embolism or other causes of fever and respiratory distress.
- Electrocardiogram (ECG): May show arrhythmias, conduction disturbances, or signs of embolic events.
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#### 7. Management and Treatment
- Acute Management:
- Empiric Antibiotic Therapy: Broad-spectrum antibiotics initially, followed by targeted therapy based on blood culture results.
- Vancomycin (for MRSA) and ceftriaxone (for Streptococcus viridans) are commonly used for empiric therapy.
- For fungal endocarditis, amphotericin B or fluconazole may be used.
- Surgical Intervention:
- Valve repair or replacement may be necessary in cases of severe valve
damage or in the presence of large vegetations causing embolism.
- Surgery is also indicated in patients with heart failure due to valve destruction or those with persistent infection despite appropriate antibiotics.
- Prolonged Therapy:
- Antibiotics are continued for several weeks (typically 4-6 weeks) to ensure complete eradication of the infection.
- Adjunctive Treatment:
- Heart failure management: Including diuretics and ACE inhibitors in patients with heart failure.
- Anticoagulation: Generally avoided due to the risk of embolism from vegetations, except in specific cases.
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#### 8. Prevention and Screening
- Primary Prevention:
- Antibiotic prophylaxis is recommended before certain dental and surgical procedures in patients at high risk of endocarditis (e.g., those with prosthetic heart valves or a history of infective endocarditis).
- Good oral hygiene and regular dental check-ups to reduce the risk of bacteremia.
- Secondary Prevention:
- Regular follow-up for high-risk patients after episodes of endocarditis, including continued monitoring for potential complications and recurrence.
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#### 9. Patient Education and Self-Care
- Essential Information:
- Educating patients on the importance of adherence to antibiotics during dental or surgical procedures.
- Recognizing the signs of infection and the need for prompt medical attention (fever, chills, fatigue).
- Lifestyle Modifications:
- Maintaining good oral hygiene, quitting smoking, and managing predisposing conditions such as diabetes or hypertension.
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#### 10. Recent Research and Advancements
- Emerging Antimicrobials: New antibiotics targeting resistant organisms like MRSA and enterococci.
- Prosthetic Valve Endocarditis: Research into less invasive treatment options and the role of antimicrobial-coated prosthetic valves.
- Genetic Factors: Investigating the role of host genetics in susceptibility to infective endocarditis and outcomes after treatment.
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#### 11. Prognosis and Complications
- Expected Disease Course:
The prognosis depends on the severity of the infection, the organism involved, and the presence of complications like septic embolism or heart failure.
- Acute Endocarditis: High mortality if untreated, but prompt treatment can improve outcomes.
- Subacute Endocarditis: More indolent course with a better prognosis if treated early.
- Complications:
- Heart failure, arrhythmias, septic emboli, and organ infarction are common complications, particularly in the absence of timely treatment.
- Long-Term Outlook:
Prognosis can be favorable with appropriate and timely treatment, but it remains poor in cases with significant valve damage or complications like multi-organ failure. Mortality rates are higher in older adults and those with prosthetic valves or IV drug use.
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#### 12. References and Further Reading
- Evidence-Based Guidelines: ESC and AHA guidelines on the management of infective endocarditis.
- Clinical Trials: Ongoing trials exploring new antibiotic regimens and surgical techniques.
- Textbooks: "Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine" for in-depth cardiovascular disease management.