Infective Endocarditis Flashcards
What is infective endocarditis?
Microbial infection of the endocardium.
What is a vegetation?
the classic lesion of this disease
3 types
acute, subacute, chronic
Native?
Endocarditis of the valves.
Prostetic
duh
Two mechanisms of bacterial adherence to the valvular endothelium?
Direct contact leading to a coagulum which pathogens bind to. Leads to a progressively larger vegetation.
Local inflammation promotes the expression of transmembrane proteins like FIBRONECTIN. Pathogens like S. aureus can bind fibronectin.
Describe the pathogenesis of Endocarditis
First there is an injury caused by either a high velocity of blood flow due to an abnormal valve or some sort of intravascular hardware. This injury leads to platelett adherence and thrombus formation. If bacteria enter the bloodstream, they adhere to the injured surface.
Complications of IE
Embolization, Metastatic infection, valve destruction, immune complex injury, local extension of infection
What sex is more likely to get IE
Men unless under 30…then women carry a higher risk.
Most common risk factor
Degenerative heart disease
Most common underlying cardiac lesions
MVP,Degenerative valvular lesions, Bicuspid aortic valve, prosthetic valve
In regards to prosthetic valve endocarditis, what organism is most responsible for IE that is aquired less than 1 year after surgery? More than 1 year?
Staph under 1 year
More closely resembles native valve endocarditis over 1 year out
Aortic root abcess is most common with what type of endocarditis?
Aortic Prosthetic valve endocarditis
Most common organism?
GRAM POSITIVE
Most common = Staph Aureus (acute IE)
Viridians strptococci seen where
Subacute IE (70%)
Common gram Negatives
HACEK Haphrophilus- most common Actinomycetocomitans C hominis Ecceredens Kingae
When do we see fungal endocarditis
IV drug use….Candida most common
Most common cause of culture negative Endocarditis
Prior antibiotic use- prevents the organism from growing in culture
Nosocomial IE (hospital acquired) usually due to?
Infected lines
Most common valve affected in IE from IVDU?
Tricuspid
Common IE presentation
Fever, chills, poor appetite, weight loss
30% may have emboli to brain, lung, or spleen.
True, seen more frequently in the developing world.
Subacute IE usually presents with what type of symptoms?
Nonspecific (fever, sweats, dyspnea, weakness, anorexia)
Physical findings
Splinter hemorrhages, Osler's nodes, Janeway lesions Petechiae Roth spots on fundoscopic exams Heart murmurs Enlarged or tender spleen
Read over Duke Criteria …pg 10
ok
In subacute pts, you may be able to withhold treatment for a short period of time in order to get blood cultures. In pts with high fever, sepsis, other acute signs…must give antibiotics. Take a blood sample first though
True
What diagnostic approach do you take with Culture negative Endocarditis?
More cultures, serological testing for the ella species, PCR of infected material.
TEE?
Transesophageal echocardiogram…more sensitive than transthoracic. TEE is of benefit when evaluating right sided heart valves.
Echocardiography guidelines
TTE initially, TEE in pts with prosthetic valves.
Detection of a vegetation with TTE is a positive test. Negative studies should be followd with TEE
In low risk pts, a negative TTE makes IE
Unlikely
Five risk factors that, when absent, make IE unlikely as long as the TTE in negative?
prosthetic valve, + blood culture, IV drug misuse, central venous line, signs of embolism
Limitations of echocardiography
Falsely negative early in disease, False positive with thickened valve leaflets, Inability to distinguish healed from active vegetations, Lower sensitivity in those with prostheses.
Management of IE
Iv Antibiotics 4-6 weeks, close management for continued infection or further valve injury
Who needs urgent surgery?
Hemodynamics compromised due to valve destruction
Persistent fever even with Antibiotics,
Development of abcesses or fistulae due to perivalvular infection
Involvement of highly resistant organisms
Large vegetations greater than 1 cm
