Concept and Etiology:
Infective endocarditis is an infection of the heart valves and/or inner
layers of the heart (endocardium) and is caused by bacteria that get
into the blood stream and affect the heart if there is any damage to
those areas of the heart. “Streptococci and Staphylococcus aureus
cause 80 to 90% of cases. Enterococci, gram-negative bacilli, HACEK
organisms (Haemophilus sp, Actinobacillus actinomycetemcomitans,
Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae),
and fungi cause most of the rest.” (Armstrong, 2017)
How does the disease affect the cardiovascular and hematopoietic
body systems in particular?
A damaged heart valve or damaged endocardium attracts fibrin,
forming a fibrin platelet thrombus in the affected area. This is called
vegetation. At this point the vegetation is not infected with bacteria.
The introduction of bacteria (listed above) into the bloodstream then
colonize along the vegetation infecting it. “Interactions between
bacterial cells, platelets and white blood cells occur through the
activation of an inflammatory response”. (Deviri, 2007) The damage
that is done to the heart can lead to the release of emboli which can
cause embolisms. “These emboli can cause serious damage and often
life threatening complications such as myocardial infarction, stroke,
seizures, and pulmonary embolism.” (Story, 2018, pg 81)
How does it deviate from the definition of health discussed in
Module One?
Infective endocarditis puts the body out of homeostasis. This puts
the body in a state where the health of the body is greatly affected.
The body’s healing mechanism can actually help to cause more
damage in this instance because one of the things the body uses to
fight infections and lesions is to send platelets and fibrin to the area
affected. This can actually aid the lesions being formed on the
affected area.
Classification:
How is the disease classified?
There are several classifications of infective endocarditis. “Subacute
bacterial endocarditis (SBE), although aggressive, usually develops
insidiously and progresses slowly (i.e., over weeks to months). Often,
no source of infection or portal of entry is evident. SBE is caused
most commonly by streptococci (especially viridians, microaerophilic,
anaerobic, and no enterococcal group D streptococci and
enterococci) and less commonly by S. aureus, Staphylococcus
epidermidis, Gemella morbillorum, Abiotrophia defectiva (formerly,
Streptococcus defectivus), Granulicatella sp, and fastidious
Haemophilus sp. SBE often develops on abnormal valves after
asymptomatic bacteremia due to periodontal, GI, or GU infections.
Acute bacterial endocarditis (ABE) usually develops abruptly and
progresses rapidly (ie, over days). A source of infection or portal of
entry is often evident. When bacteria are virulent or bacterial
exposure is massive, ABE can affect normal valves. It is usually
caused by S. aureus, group A homolytic streptococci, pneumococci,
or gonococci. Prosthetic valvular endocarditis (PVE) develops in 2 to
3% of patients within 1 yr. after valve replacement and in 0.5%/yr
thereafter. It is more common after aortic than after mitral valve
replacement and affects mechanical and bioprosthetic valves equally.
Early-onset infections (< 2 mo. after surgery) are caused mainly by
contamination during surgery with antimicrobial-resistant bacteria
(e.g., S. epidermidis, diphtheroid, coliform bacilli, Candida sp,
Aspergillus sp). Late-onset infections are caused mainly by
contamination with low-virulence organisms during surgery or by
transient asymptomatic bacteraemia’s, most often with streptococci;
S. epidermidis; diphtheroid; and the fastidious gram-negative bacilli,
Haemophilus sp, Actinobacillus actinomycetemcomitans, and Cardio
bacterium hominis.” (Armstrong, 2017)
Clinical Manifestations (Symptoms and Signs):
What are the symptoms and signs of the disease or disorder?
Signs: (what others see/detect)
o Flu-like symptoms, such as fever and chills
o A new or changed heart murmur o Embolism
o Night sweats o Edema
o Shortness of breath
o Swelling in your feet, legs or abdomen
o Janeway lesions, which are red spots on the soles of your feet or
the palms of your hands
o Osler's nodes, which are red, tender spots under the skin of your
fingers or toes o Petechiae (puh-TEE-key-e), which are tiny purple or
red spots on the skin, whites of your eyes, or inside your mouth
Symptoms: (what patient feels)
o Fatigue o Aching joints and muscles
o Chest pain when you breathe
o Unexplained weight loss (Endocarditis, 2018)
Diagnostic Tests:
What are some additional diagnostic tests that can be done to
illuminate the diagnosis? For example, when you injure your ankle,
they take an x-ray to determine if it is broken or sprained.
o H&P o Physical exam o Blood cultures
o CBC
o Urinalysis o Serum rheumatoid factor
o Erythrocyte Sedimentation rate (sed rate)
o EKG
o Echocardiogram
It should be said that because infective endocarditis is hard to
initially detect, if a patient is showing signs of a fever but not
showing any readily detectable infection. This is definitely something
that should be considered if the patient has a new or changed heart
murmur.
References
Armstrong, G. P., MD. (2017, September). Infective Endocarditis -
Cardiovascular Disorders. Retrieved November 7, 2021,
from https://www.merckmanuals.com/professional/cardiovasculardi
sorders/endocarditis/infective-endocarditis
Deviri, E., & Glenville, B. E. (2007, June 8). Inflammatory Response in
Infective Endocarditis [PDF]. Jerusalem, Israel: European Journal of
Inflammation. Story, L. (2018). Pathophysiology: A practical
approach. Burlington, MA: Jones & Bartlett Learning
