Infective Endocarditis Flashcards
What is infective endocarditis?
Infective endocarditis is a serious infection of the inner lining of the endocardium or the heart valves typically caused by bacteria.
Which valves are most affected in Infective Endocarditis?
◾ Infective endocarditis commonly affects the left-sided heart valves i.e. the mitral and aortic valves.
◾ In cases involving intravenous drug use, the tricuspid valve on the right side of the heart is often affected.
Outline predisposing factors of Infective Endocarditis.
◾ Rheumatic Heart Disease
◾ Congenital malformations e.g. ASD [Atrial Septal Defect], VSD [Ventricular Septal Defect]
◾ Calcific aortic stenosis [calcification of the aortic valve can create rough surfaces that are prone to bacterial colonization and infection]
◾ Aging valves [heart valves may become thickened and calcified with age]
◾ Host factors: neutropenia [low white blood cell count], immunosuppression, alcoholism, diabetes mellitus, drug abuse
Further notes:
“The epidemiology of infective endocarditis in children has shifted in recent years with less rheumatic fever, more congenital heart disease survival, and increased use of central venous catheters in children with chronic illness.”
Name two highly virulent bacteria that cause acute infective endocarditis.
(1) Staphylococcus aureus [50%]
(2) Streptococcus pyogenes [35%]
List some common sources of infection in acute Infective Endocarditis.
(1) Dental procedures
(2) Skin infections
(3) Intravenous drug use
(4) UTIs
(5) Respiratory infections
(6) Surgical procedures
(7) Indwelling medical devices [e.g. catheters, pacemakers, or prosthetic heart valves can become infected and serve as a source of bacteria]
Why are there no organisms isolated in 5-10% of acute Infective Endocarditis cases?
This is due to difficulty in culturing and previous antibiotic therapy.
Outline clinical features of acute Infective Endocarditis.
◾ Rapidly progressive high fever and chills
◾ Heart failure sets in with cardiac murmurs [caused by turbulent blood flow through the damaged valves]
◾ Embolic phenomena from the heart vegetations: Vegetations (clumps of bacteria and cellular debris) can form on the heart valves. Pieces of these vegetations can break off and travel through the bloodstream, causing embolic phenomena. Common manifestations include:
(i) Janeway lesions: painless, small, red or purple spots on the palms or soles
(ii) Splinter hemorrhages: tiny blood clots that run vertically under the nails
(iii) Pustular skin lesions: small pus-filled bumps on the skin
◾ Anemia
◾ Splenomegaly
◾ Glomerulonephritis causing hematuria
◾ Death within days to weeks due to infections
Further notes:
FROM JANE
Fever
Roth spots (retinal hemorrhages with pale centers)
Osler nodes (painful, red, raised lesions on the hands and feet)
Murmur (new or changed heart murmur)
Janeway lesions (painless, flat, red spots on the palms and soles)
Anemia
Nail-bed hemorrhages (splinter hemorrhages)
Emboli (septic emboli causing infarctions in various organs)
[3-minute video]: Janeway lesions vs Osler’s Nodes
Briefly discuss the morphology of acute Infective Endocarditis.
◾ Aortic and mitral valves are involved in 80-90% of cases. These valves are particularly susceptible to infection due to their high-pressure environment and the turbulent blood flow that can cause damage and make them more prone to bacterial colonization.
◾ Bulky friable masses of thrombi containing the causative organisms are found hanging on valve leaflets. These masses can be quite large, some reaching up to 7 cm in diameter.
What are the vegetations in infective endocarditis composed of?
The vegetations are composed of a complex mixture of platelets, fibrin, and bacteria, forming a protective environment for the bacteria.
How does the platelet and fibrin matrix protect bacteria in infective endocarditis?
The platelet and fibrin matrix provides a shield that prevents phagocytes from accessing and eliminating the bacteria, allowing them to thrive and multiply.
What role does platelet aggregation play in infective endocarditis?
Pathogenic bacteria often induce platelet aggregation, which contributes to the formation of vegetations and helps the bacteria adhere to the heart valves and evade the immune system.
Under histological examination, kidney deposits are observed in upto 1/3 of patients. These deposits cause ________.
focal glomerulonephritis.
What are the systemic complications related to embolic phenomena in infective endocarditis?
(1) Cerebral emboli and abscesses: Emboli can travel to the brain, causing strokes or abscesses.
(2) Splenic infarcts and abscesses: Emboli can travel to the spleen, causing infarcts (tissue death due to lack of blood supply) or abscesses.
(3) Lung Abscess: Emboli can travel to the lungs, causing abscesses.
What are common causes of death associated with acute Infective Endocarditis?
(1) Cardiac failure
◾ Valvular damage: The infection can cause significant damage to the heart valves, leading to their dysfunction. This can result in heart failure, where the heart is unable to pump blood effectively.
◾ Rupture of chordae tendinae: these anchor the heart valves. If they rupture, it can lead to severe valve dysfunction and contribute to heart failure.
(2) Embolic phenomena
◾ To the heart: Emboli can travel to the coronary arteries, causing myocardial infarction.
◾ To the brain: Emboli can travel to the brain, causing strokes or brain infarcts, which can be fatal.
(3) Uncontrolled sepsis
◾ The infection can spread throughout the body, leading to sepsis, a life-threatening condition characterized by widespread inflammation and organ failure.
(4) Arrhythmias
◾ The infection and resulting damage to the heart can cause arrhythmias.
(5) Rupture of mycotic aneurysms
◾ Mycotic aneurysms are infected aneurysms that can form in the blood vessels. If these aneurysms rupture, it can lead to severe internal bleeding and death.
Further notes:
An aneurysm is an abnormal bulge or ballooning in the wall of a blood vessel.
