Infective Endocarditis Overview
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Questions and Answers

Which of the following is NOT a common location for endocarditis vegetation?

  • Chordae tendinae
  • Surface of the valves
  • Edges of septal defects
  • Skin surface (correct)

    • What is the primary composition of vegetations found in infective endocarditis?

  • Primarily composed of red blood cells and plasma.
  • Mainly made up of collagen and elastic fibers.
  • A collection of mineral deposits and dead tissue.
  • Composed of platelets, fibrin, microorganisms, and inflammatory cells. (correct)

    • Which term specifically refers to a microbial infection of the heart involving bacteria.

  • Mural endocarditis
  • Bacterial endocarditis (BEL) (correct)
  • Vegetative endocarditis
  • Infective endocarditis (IE)

    • What is a synonym of infective endocarditis (IE)?

    <p>Microbial infection (B)</p> Signup and view all the answers

    Which type of organism is LEAST likely to cause an endocarditis infection?

    <p>Viral (D)</p> Signup and view all the answers

    What is the most common cardiac consequence of infective endocarditis (IE) related to valve leaflet injury?

    <p>Valve insufficiency due to bacterial enzyme destruction. (C)</p> Signup and view all the answers

    In dogs with Bartonella endocarditis, which valve is most commonly affected?

    <p>Aortic valve (C)</p> Signup and view all the answers

    What percentage of dogs with Bartonella endocarditis typically present with fever?

    <p>20% (C)</p> Signup and view all the answers

    Which bacterial species is most frequently cultured from cattle with infective endocarditis?

    <p>Trueperella pyogenes (B)</p> Signup and view all the answers

    What is a potential consequence of the extension of infective endocarditis into surrounding cardiac tissue?

    <p>Atrioventricular or bundle branch blocks (B)</p> Signup and view all the answers

    What percentage of cases with infective endocarditis show evidence of embolic disease at necropsy?

    <p>Approximately 84% (A)</p> Signup and view all the answers

    According to the information provided, which of these is a less common site for embolic events in cases of infective endocarditis?

    <p>Brain (A)</p> Signup and view all the answers

    What factor, according to the text, increases the risk of embolic disease in infective endocarditis?

    <p>Larger, mobile vegetations of the heart &gt;10-15mm (C)</p> Signup and view all the answers

    Which of these immune mediated diseases is mentioned as a possible sequelae of endocarditis?

    <p>Glomerulonephritis (C)</p> Signup and view all the answers

    What percentage of cats with infective endocarditis might experience renal failure?

    <p>Up to 33% (A)</p> Signup and view all the answers

    In small animals, which heart valves are most frequently affected by endocarditis?

    <p>Mitral and aortic valves (C)</p> Signup and view all the answers

    What is the primary way that bacteria contribute to the development of endocarditis?

    <p>By secreting enzymes that destroy valve tissue (B)</p> Signup and view all the answers

    Which factor initiates the process that leads to the formation of non-bacterial thrombotic endocarditis (NBTE)?

    <p>Endothelial damage (D)</p> Signup and view all the answers

    What is the most common location of endocarditis lesions in cows?

    <p>Tricuspid valve (B)</p> Signup and view all the answers

    What is a common feature of endocarditis lesions in terms of pressure?

    <p>They are most often associated with the lower-pressure side of the valve (D)</p> Signup and view all the answers

    Which of the following bacterial species is commonly associated with endocarditis in dogs?

    <p>Staphylococcus aureus (C)</p> Signup and view all the answers

    In which animal species is endocarditis more likely to present with left-sided valve involvement, including mural lesions?

    <p>Horses, pigs, and camelids (A)</p> Signup and view all the answers

    What is a potential complication that can occur when endocarditis lesions fragment?

    <p>Bacteremia (C)</p> Signup and view all the answers

    What is the typical appearance of gross lesions in endocarditis?

    <p>Friable, rough, irregular, yellowish raised proliferative lesions (B)</p> Signup and view all the answers

    Which animal species is most commonly affected by endocarditis?

    <p>Cows (A)</p> Signup and view all the answers

    According to the information, what percentage of dogs in a referral population are diagnosed with endocarditis?

    <p>0.05 - 0.08% (D)</p> Signup and view all the answers

    What is the initial step in the pathogenesis of endocarditis?

    <p>Endothelial damage/injury (B)</p> Signup and view all the answers

    What is the role of Non-Bacterial Thrombotic Endocarditis (NBTE) in infective endocarditis?

    <p>It creates a surface for bacterial colonization. (B)</p> Signup and view all the answers

    Which of the following is NOT a cause of endothelial damage leading to endocarditis?

    <p>Myxomatous degeneration (B)</p> Signup and view all the answers

    What proportion of veterinary cases with endocarditis have an underlying cardiac defect?

    <p>6 - 13% (D)</p> Signup and view all the answers

    What specific pre-existing condition is reported in the majority of veterinary cases of endocarditis that do have a predisposing cardiac abnormality?

    <p>Congenital subaortic stenosis (A)</p> Signup and view all the answers

    Which of the following is NOT typically considered a major criterion in the modified Duke criteria for diagnosing infectious endocarditis (IE)?

    <p>Presence of predisposing factor such as medium to large dog (B)</p> Signup and view all the answers

    A patient presents with a new diastolic murmur at the left base of the heart. Based on the information provided, what valvular issue is MOST likely to be associated with this finding?

    <p>Aortic valve regurgitation (D)</p> Signup and view all the answers

    Which of the following is the most accurate statement regarding serum biochemistry findings associated with infectious endocarditis (IE)?

    <p>Both azotemia and elevated globulins are commonly observed in patients with IE. (A)</p> Signup and view all the answers

    What is the clinical significance of finding a new systolic murmur at the left apex with a patient suspected of having IE?

    <p>It is most likely associated with mitral valve regurgitation. (A)</p> Signup and view all the answers

    A patient with suspected IE has tachycardia, hyperkinetic pulses and an arrhythmia. What category does these cardiac findings fall under?

    <p>Other possible cardiac findings (C)</p> Signup and view all the answers

    Which of these findings, if present in a patient, would be considered a minor criterion for infectious endocarditis according to the modified Duke criteria?

    <p>A Bartonella serology result greater than or equal to 1:1024 (C)</p> Signup and view all the answers

    Which of the following is most likely to be documented in a complete blood count (CBC) of a patient with IE?

    <p>Leukocytosis with neutrophilia or monocytosis (B)</p> Signup and view all the answers

    What is the likely cause of a stenotic semilunar valve with a concurrent ejection murmur in a patient with IE?

    <p>A large vegetation growing on the valve (B)</p> Signup and view all the answers

    Flashcards

    Infective endocarditis (IE)

    A microbial infection affecting the inner lining of the heart, caused by bacteria or fungi.

    Bacterial endocarditis (BEL)

    A specific type of infective endocarditis caused by bacterial infection.

    Vegetative endocarditis

    A condition characterized by vegetations of platelets, fibrin, microorganisms, and inflammatory cells on heart valves.

    Chordae tendinae

    Tendinous cords connecting the papillary muscles to the heart valves, helping to prevent valve prolapse.

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    Rickettsial organisms

    A group of bacteria that can cause diseases, including conditions affecting the heart.

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    Endocarditis

    Inflammatory/infectious condition of the heart valves.

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    Endocardiosis

    Degenerative/myxomatous change in heart valves with no infection involved.

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    Incidence in cows

    0.016 – 0.12 % of cattle populations affected by endocarditis.

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    Incidence in dogs

    0.05 – 0.08% of dogs affected, primarily middle-aged or older.

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    Pathogenesis of endocarditis

    Sequence including endothelial damage, thrombus formation, and bacterial colonization.

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    Healthy endothelium

    Resistant to bacterial colonization unless damaged.

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    Congenital heart defects in cases

    Underlying defects found in only 6-13% of endocarditis cases.

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    Bacterial colonization steps

    Includes forming thrombus, bacteremia, and lesion extension.

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    Embolic disease

    A condition caused by emboli traveling to distant sites, leading to organ damage.

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    Common sites for embolic disease

    Most affected organs are the kidneys (65%) and spleen (45%) from embolic disease.

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    Vegetations size risk

    Larger, mobile vegetations (>10-15 mm) pose a higher risk for systemic consequences.

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    Immune-mediated disease

    Results from immune responses leading to tissue damage, often affecting joints and kidneys.

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    Septic shock

    A severe condition from infection leading to dangerously low blood pressure and organ failure.

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    Bartonella Endocarditis

    A heart infection with a strong preference for the aortic valve, associated with poor outcomes like CHF.

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    Trueperella pyogenes

    An etiological agent commonly found in cattle, responsible for about 80% of cultures.

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    Insufficiency

    A condition where valve leaflet injury leads to regurgitation, volume overload, and heart failure.

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    Cardiac Hypertrophy

    Increased heart workload resulting in concentric thickening of the heart muscle due to obstruction.

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    Purulent Pericarditis

    An infection of the pericardial tissue characterized by pus formation, often due to bacterial infection.

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    Risk Factors for IE

    Prior/current infection and immunosuppressive conditions increase IE risk.

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    Clinical Finding: Fever

    Fever can indicate systemic infection, often present in IE.

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    Joint Effusion in IE

    Palpable joint effusion may occur due to inflammation or infection.

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    Ejection Murmur

    A type of heart murmur caused by increased blood flow or stenosis.

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    Signs of Vasculitis

    Includes cutaneous hemorrhage and thrombosis, related to systemic infection.

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    CBC Findings in IE

    Leukocytosis and anemia may appear in Complete Blood Cell Count in IE.

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    Major Criteria: Echocardiogram

    A positive echocardiogram shows vegetative lesions or abscesses, indicating IE.

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    Minor Criteria: Fever and Predisposing Factors

    Fever and certain conditions (like dog size) can be minor supporters of IE diagnosis.

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    Turbulence Trauma

    Pathological changes caused by turbulent blood flow leading to vessel damage.

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    Endothelial damage

    Injury to the inner lining of blood vessels, triggering complications.

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    Platelet-fibrin deposition

    Accumulation of platelets and fibrin at injury sites, forming clots.

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    Non-bacterial thrombotic endocarditis

    Heart valve infection without bacteria, often linked to other conditions.

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    Mature vegetation

    A mass formed from platelets and bacteria on heart valves.

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    Common etiologic agents

    Specific infectious organisms associated with endocarditis in small animals.

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    Mitral and aortic valves in small animals

    Valves mostly affected by endocarditis in dogs and cats, located on the left side.

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    Right-sided valves in large animals

    Infections often found in the tricuspid valve among cows, horses, and pigs.

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    Study Notes

    Acquired Valvular Disease: Infective Endocarditis

    • Infective endocarditis (IE) is an inflammation of the endocardial surface of the heart, caused by an infectious agent.
    • IE is characterized by microbial infection (bacteria, fungi), bacterial endocarditis, or vegetations composed of platelets, fibrin, microorganisms, and inflammatory cells.
    • The condition often involves the valve surfaces, mural (wall), or edges of septal defects.
    • Chordae tendinae can also be involved.

    Learning Objectives

    • Understand the pathophysiology of endocarditis
    • Review common etiological agents
    • Describe clinical signs and diagnostic findings of endocarditis
    • Describe appropriate treatment approaches

    What is Infective Endocarditis?

    • IE is inflammation of the endocardial surface by infectious agents.
    • Vegetative lesions (composed of platelets, fibrin, microorganisms, and inflammatory cells) form with adherence to cardiac valves.
    • Bacterial (including Rickettsia and fungi) are common agents.

    Endocarditis vs. Endocardiosis

    • Endocardiosis is a degenerative/myxomatous thickening of valve margins (smooth, glistening, nodular).
    • Endocarditis is an inflammatory/infectious condition with friable, rough, irregular yellowish lesions (vegetative).

    Incidence/Prevalence

    • Cows: Relatively common (0.016-0.12% of cattle populations). Important in hardware disease.
    • Dogs: Uncommon in the general population, but more observed in referral populations (0.05% - 0.08%).
    • Horses, pigs, camelids: Sporadic, with potentially mural involvement (wall) in some.
    • Cats: Rare (0.006-0.018% in referral populations).
    • Avians: Few cases documented.

    Pathogenesis

    • 1. Endothelial damage/injury: Necessary for bacterial colonization. Can be caused by direct trauma, inflammation, or turbulent blood flow.
    • 2. Formation of non-bacterial thrombotic endocarditis (NBTE): Extracellular proteins (thromboplastin, tissue factor), trigger coagulation, which forms a coagulum (fibrinogen, fibrin, platelet proteins).
    • 3. Bacteremia: Transient or persistent bacteremia. Predisposing factors include chronic infections (UTI/diskospondylitis, prostatitis, pneumonia, pyoderma), GI/GU tract surgeries, and immunosuppression.
    • 4. Bacterial colonization of NBTE: Circulating bacteria adhere to thrombus, and bacteria that easily attach include Staphylococcus and Streptococcus species. These bacteria have surface proteins (MSCRAMMS) that bind to fibrin/fibrinectin.
    • 5. Lesion extension: Bacteria become embedded, inducing both tissue factor production and platelet aggregation, shielding itself from the host's defenses and antimicrobial drugs, leading to lesion expansion.

    Lesion Pathology

    • Small Animals: Almost exclusively mitral and aortic valves. Commonly associated with the low-pressure side of the valve lesion.
    • Large Animals (Cows): Right-sided valves (especially tricuspid valve).

    Etiologic Agents

    • Small Animals: Staphylococcus spp., Streptococcus spp., Escherichia coli, Bartonella spp., Pasteurella spp. (Agent ID only in 60% of cases)
    • Large Animals (Cows): Trueperella pyogenes, Streptococcus spp., Escherichia coli.
    • Large Animals (Horses): Actinobacillus, Streptococcus spp., Staphylococcus spp.
    • Large Animals (Pigs): Streptococcus, Erysipelothrix.

    Bartonella Endocarditis

    • Aortic valve predilection.
    • Commonly associated with poorer outcomes (CHF, earlier death).
    • Affected dogs are usually afebrile.
    • Difficult to isolate from blood, since it can be culture negative with routine methods.

    Cardiac Consequences of IE (Local)

    • Valve leaflet injury: Leads to insufficiency (most common)
    • Necrosis/perforation: Leads to valvular regurgitation
    • Volume overload: Could result in left heart enlargement, CHF, obstruction/stenosis, increasing cardiac workload.
    • Extension of infection: Can lead to blocks of the atrioventricular/bundle branch, abscess formation, purulent pericarditis, or myocarditis, along with intracardiac perforations.

    Systemic Consequences of IE (Metastatic)

    • Embolic disease: End-organ infarction (metastatic infection). Kidneys and spleen are most commonly affected. Larger mobile vegetations lead to an increased risk.
    • Immune-mediated disease: Cell-mediated/humoral responses, leading to circulating immune complex deposition, activating complement and damage to tissue. Causes include polyarthritis or glomerulonephritis. Infarction or metastatic infection are also possible.

    Possible History/Clinical Findings

    • Risk factors: Prior/current infection and immunosuppressive disease.
    • Clinical signs: Fever, lethargy, weight loss, a constitutional illness, cough, signs of vasculitis (cutaneous hemorrhage/thrombosis), palpable joint effusion, new heart murmurs (ejection murmurs, increased flow, stenotic murmur, regurgitant murmur), arrhythmias (systolic left base or right apex murmur), signs of CHF.

    Diagnosis - Lab Findings

    • Complete Blood Cell Count (CBC): Variable; Might show leukocytosis (neutrophils, monocytes), anemia.
    • Serum Biochemistry: Variable; Could show azotemia or elevated globulins.
    • Urinalysis: Variable, possibly pyuria.

    Diagnosis - Echocardiography

    • Vital tool for detecting IE antemortem. IE is characterized by hyperechoic, oscillating, and irregular masses attached to the endocardial cardiac surface.

    Diagnosis - Blood Cultures

    • Essential to confirm the diagnosis and guide therapy.
    • Ideally, 3-4 aseptically obtained samples (10ml) over 24 hours, or 2-3 samples collected 1 hour apart (critically ill).
    • Blood cultures frequently display negative results (40-70% of cases), particularly for Bartonella, necessitating PCR or serology.

    Practice Case: Bubba

    • 6-year-old Newfoundland dog.
    • Presenting complaint: Lethargy, hyporexia; tachycardia (HR: 170 bpm), panting respirations, fever (T: 103.5F).
    • History: Diagnosed previously with SAS, prescribed antibiotics and NSAIDS 1 week ago without resolution.

    Modified Duke Criteria

    • Major criteria: Positive echocardiogram, oscillating/vegetative/erosive lesions, or an abscess, new valvular insufficiency with two-positive blood cultures.
    • Minor criteria: Fever, predisposing factors, evidence of systemic complications(thromboembolic disease, immune-mediated disease), positive or negative blood culture (not meeting major criteria), and Bartonella serology ≥1:1024.

    Treatment

    • Goals: Sterilize vegetation, address cardiac sequelae, and manage systemic complications.
    • Antibiotics: Long term (Beta-lactam + fluoroquinolone/aminoglycoside/azithromycin). Empirical choices pending culture results.
    • Aggressive, prolonged therapy!
    • Extended durations: Ideally IV antibiotics for a week, progressing to longer-term oral antibiotics (at least 12 weeks) is generally advised.
    • CHF management: Standard therapy, including cardiac evaluation (FOPS, echocardiography 2-6 weeks after initiation of antibiotic therapy).
    • Surgical options: Potential, but with low prevalence.
    • Supplementary considerations: Corticosteroids are contraindicated. Antiplatelets/thrombotics are often controversial. Renal disease should be treated; lameness, symptomatically.

    Prognosis

    • Dependent on: Microorganism involved, infection location in relation to valves (left or right sided).
    • Overall: Guarded to poor.
    • Common complications: CHF and embolic complications.
    • Estimates: Vary by species (unknown in cows, 54 days in dogs, varying in horses, pigs, camelids).

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    CRHII Infective Endocarditis Student 2025 PDF

    Description

    This quiz explores the essential aspects of Infective Endocarditis (IE), focusing on its pathophysiology, common infectious agents, and clinical manifestations. Learn about the diagnostic criteria and treatment options for this crucial cardiovascular condition.

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