Endocarditis

Overview

Endocarditis is a serious and potentially life-threatening infection of the endocardium, which is the inner lining of the heart chambers and valves. This condition occurs when bacteria, fungi, or other microorganisms enter the bloodstream and attach to damaged or abnormal heart valves or other areas of the heart's inner lining. Once established, these organisms form infected masses called vegetations that can damage heart valves, disrupt normal heart function, and spread infection throughout the body.

The condition can be classified as either acute or subacute based on the speed of onset and severity. Acute endocarditis develops rapidly over days to weeks and is typically caused by aggressive bacteria like Staphylococcus aureus. It often affects previously normal heart valves and can quickly cause severe complications. Subacute endocarditis develops more slowly over weeks to months, usually involving less virulent organisms like viridans group streptococci, and typically affects abnormal or damaged valves.

Endocarditis can affect anyone, but certain groups are at higher risk, including people with pre-existing heart conditions, artificial heart valves, congenital heart defects, or those who inject drugs. The incidence has been increasing due to factors such as more frequent use of intravascular devices, increasing numbers of people with prosthetic valves, and the opioid epidemic leading to more intravenous drug use.

Without prompt treatment, endocarditis can lead to serious complications including heart failure, stroke, septic embolization to other organs, abscess formation, and death. However, with early diagnosis and appropriate antibiotic therapy, often combined with surgical intervention when necessary, the prognosis can be significantly improved. The key to successful treatment is early recognition of symptoms and immediate medical attention, as delays in treatment can result in irreversible damage to heart valves and other vital organs.

Symptoms

Endocarditis symptoms can vary widely depending on the type of organism involved, the patient's overall health, and whether the infection is acute or subacute.

Primary Symptoms

Cardiac Symptoms

Heart-Related Signs

• New or changing heart murmur: Most significant cardiac finding
• Palpitations: Feeling of irregular or rapid heartbeat
• Chest pain: May be sharp, aching, or pressure-like
• Shortness of breath: At rest or with minimal exertion
• Fatigue: Severe tiredness and weakness
• Exercise intolerance: Inability to perform usual activities

Signs of Heart Failure

• Swelling in legs, ankles, or abdomen
• Difficulty lying flat
• Waking up short of breath at night
• Rapid weight gain from fluid retention
• Decreased urine output

Systemic Symptoms

Constitutional Symptoms

• Fever: Often persistent, may be high-grade (>101°F/38.3°C)
• Chills and rigors: Severe shaking chills
• Night sweats: Profuse sweating during sleep
• Weight loss: Unintentional loss of appetite and weight
• Malaise: General feeling of being unwell
• Headache: Persistent or severe headaches

Inflammatory Symptoms

• Joint pain and swelling (arthralgia/arthritis)
• Muscle aches and pains
• General body aches
• Low-grade fever in subacute cases

Skin and External Signs

Classic Peripheral Signs

• Splinter hemorrhages: Red or black lines under fingernails
• Petechiae: Small red or purple spots on skin or mucous membranes
• Janeway lesions: Painless red spots on palms or soles
• Osler nodes: Painful red or purple nodes on fingers or toes
• Roth spots: Retinal hemorrhages with white centers

Other Skin Manifestations

• Pale skin or pallor
• Easy bruising
• Small blood vessel ruptures
• Clubbing of fingers (in chronic cases)

Neurological Symptoms

Central Nervous System Involvement

• Stroke symptoms: Weakness, numbness, speech problems
• Confusion: Altered mental status or delirium
• Seizures: New onset seizures
• Severe headache: May indicate brain abscess or meningitis
• Vision changes: Visual disturbances or loss
• Behavioral changes: Personality or mood changes

Embolic Complications

Systemic Embolization

• Stroke: From emboli to brain arteries
• Kidney problems: Blood in urine, decreased function
• Abdominal pain: From emboli to mesenteric arteries
• Limb pain: From peripheral arterial emboli
• Vision problems: From retinal artery emboli

Pulmonary Symptoms (Right-sided endocarditis)

• Cough, sometimes with blood
• Chest pain, especially with breathing
• Shortness of breath
• Pneumonia-like symptoms

Acute vs. Subacute Presentation

Acute Endocarditis

• Rapid onset: Days to weeks
• High fever: Often >103°F (39.4°C)
• Toxic appearance: Patient appears very ill
• Rapid progression: Quickly deteriorating condition
• Early complications: Heart failure, emboli
• Aggressive organisms: Usually Staphylococcus aureus

Subacute Endocarditis

• Insidious onset: Weeks to months
• Low-grade fever: May be absent or intermittent
• Fatigue and weakness: Prominent symptoms
• Weight loss: Gradual, unintentional
• Subtle symptoms: May be mistaken for flu
• Less virulent organisms: Often streptococci

Age-Specific Presentations

Children and Adolescents

• May have more prominent fever
• Growth failure or poor feeding (in infants)
• Irritability or behavioral changes
• School performance decline
• Joint complaints more common

Elderly Patients

• May have minimal or no fever
• Confusion or delirium more prominent
• Fatigue and weakness predominant
• Falls or functional decline
• Atypical presentations common

Prosthetic Valve Endocarditis

• Early (≤60 days): Often acute, severe presentation
• Late (>60 days): More indolent course
• Valve dysfunction: New murmur or heart failure
• Embolic events: Higher risk of complications
• Fever: May be present or absent

Drug User Endocarditis

• Right-sided involvement: Tricuspid valve commonly affected
• Pulmonary symptoms: Cough, chest pain, shortness of breath
• Recurrent pneumonia: From septic pulmonary emboli
• Injection site infections: May be present
• Multiple organism infection: Sometimes polymicrobial

Warning Signs Requiring Immediate Attention

• High fever with new heart murmur
• Sudden onset of neurological symptoms
• Severe shortness of breath or chest pain
• Signs of stroke or altered mental status
• Severe abdominal or back pain
• Blood in urine with fever
• Rapid clinical deterioration

Complications Symptoms

• Heart failure: Severe shortness of breath, swelling
• Valve rupture: Sudden severe symptoms
• Abscess formation: Persistent fever despite antibiotics
• Conduction abnormalities: Dizziness, fainting
• Pericarditis: Chest pain worse with breathing

Causes

Endocarditis is caused by microorganisms that enter the bloodstream and attach to the heart's inner lining or valves, forming infected masses called vegetations.

Bacterial Causes

Most Common Bacteria

• Staphylococcus aureus: Most common cause of acute endocarditis
• Viridans group streptococci: Common in subacute endocarditis
• Enterococci: Particularly in elderly and immunocompromised
• Staphylococcus epidermidis: Common with prosthetic valves
• Streptococcus bovis: Associated with colon cancer
• HACEK organisms: Rare but important causes

Drug-Resistant Organisms

• Methicillin-resistant Staphylococcus aureus (MRSA)
• Vancomycin-resistant enterococci (VRE)
• Extended-spectrum beta-lactamase (ESBL) producers
• Carbapenem-resistant organisms

Fungal Causes

• Candida species: Most common fungal cause
• Aspergillus: Particularly in immunocompromised
• Histoplasma: Endemic areas
• Other yeasts and molds: Various species

Routes of Infection

Bloodstream Entry Points

• Dental procedures: Tooth extractions, cleanings
• Medical procedures: Central lines, surgery, endoscopy
• Injection drug use: Contaminated needles and drugs
• Skin infections: Cellulitis, abscesses
• Respiratory infections: Pneumonia, bronchitis
• Urinary tract infections: Especially with instrumentation
• GI tract sources: Bowel procedures, infections

Healthcare-Associated Infections

• Central venous catheters
• Hemodialysis access
• Cardiac devices (pacemakers, ICDs)
• Surgical procedures
• Intravascular procedures
• Prosthetic heart valves

Pathophysiology

Steps in Infection Development

• Endothelial damage: Injury to heart valve surface
• Platelet-fibrin deposition: Formation of sterile vegetations
• Bacteremia: Organisms enter bloodstream
• Bacterial adherence: Organisms stick to vegetations
• Vegetation growth: Infected mass enlarges
• Tissue invasion: Extension into valve structures

Factors Promoting Infection

• Turbulent blood flow
• High-pressure gradients
• Abnormal valve surfaces
• Foreign material presence
• Immune system compromise

Predisposing Cardiac Conditions

High-Risk Cardiac Lesions

• Prosthetic heart valves: Mechanical or biological
• Previous endocarditis: History of infection
• Congenital heart disease: Cyanotic conditions
• Rheumatic heart disease: Damaged valves
• Mitral valve prolapse: With regurgitation
• Hypertrophic cardiomyopathy: With obstruction

Moderate-Risk Conditions

• Mitral valve prolapse without regurgitation
• Tricuspid valve disease
• Pulmonary valve disease
• Isolated atrial septal defect
• Arteriosclerotic plaques

Host Factors

Immunosuppression

• HIV/AIDS: Compromised immune system
• Diabetes mellitus: Impaired immune function
• Cancer: Disease or chemotherapy effects
• Organ transplantation: Immunosuppressive medications
• Chronic kidney disease: Uremia and dialysis
• Elderly age: Declining immune function

Other Risk Factors

• Poor dental hygiene
• Chronic alcoholism
• Malnutrition
• Chronic illness
• Recent surgery or trauma

Special Populations

Injection Drug Users

• Common organisms: S. aureus, Pseudomonas, Candida
• Right-sided involvement: Tricuspid valve commonly affected
• Contaminated needles: Direct bacterial introduction
• Adulterants in drugs: Talc, other particles
• Poor sterile technique: Increased infection risk

Healthcare Workers

• Needlestick injuries
• Exposure to resistant organisms
• Occupational risk factors
• Healthcare-associated pathogens

Geographic and Environmental Factors

• Endemic infections: Brucella, Q fever, fungal infections
• Travel history: Exposure to unusual pathogens
• Climate factors: Some organisms more common in certain areas
• Water exposure: Pseudomonas and other water-borne organisms

Prosthetic Material Infections

Early Prosthetic Valve Endocarditis (≤60 days)

• Perioperative contamination: During surgery
• Common organisms: Staphylococci, gram-negative bacilli
• Aggressive course: Rapid progression
• High mortality: Poor prognosis

Late Prosthetic Valve Endocarditis (>60 days)

• Community-acquired: Similar to native valve endocarditis
• Hematogenous seeding: From distant infection sites
• Slower progression: More indolent course
• Better prognosis: If treated appropriately

Nosocomial Endocarditis

• Intravascular devices: Central lines, arterial catheters
• Hospital procedures: Surgery, invasive diagnostics
• Resistant organisms: Hospital-acquired pathogens
• ICU patients: Multiple risk factors
• Immunocompromised hosts: Higher susceptibility

Culture-Negative Endocarditis

Causes of Negative Blood Cultures

• Prior antibiotics: Treatment before cultures obtained
• Fastidious organisms: Difficult to culture
• Non-bacterial causes: Fungi, unusual organisms
• Non-infective endocarditis: Marantic, Libman-Sacks
• Technical issues: Inadequate culture techniques

HACEK Organisms

• H: Haemophilus species
• A: Aggregatibacter actinomycetemcomitans
• C: Cardiobacterium hominis
• E: Eikenella corrodens
• K: Kingella kingae

Frequently Asked Questions