infectious bacterial endocarditis Flashcards
define IBE
an infection of the innermost layers of the heart. it may occur in people with congenital and valvular disease and those who have had rheumatic fever
what causes IBE
bacteria or yeast enter the blood stream and colonize on the valves or endocardial surface of the heart
IBE etiologies with native valves diseases
underlying valvular disease -RHD -bicuspid aortic valves -calcified valves -mitral valve prolapse increase in regurgitant, low pressure valves
IBE etiologies with native valves and hearth care
Health Care Associated Bacteremia
- Dental procedures
- Respiratory procedures
- Urologic procedures
- Lower GI procedures
- Surgical procedures
- INVASIVE LINES / DEVICES (PICC, art lines, IJ, dialysis catheters)
IBE etiologies with native valves and addication
IV drug use
s. aureus: 80-90%
enterococci
streptococci
IBE etiologies bioprosthetic valve
Bioprosthetic valve infections
Primarily involve the sewing ring / native annulus along suture line
IBE etiologies machanical valve
Mechanical valve infections
Inward bacterial growth on the sewing ring results in a mass that impedes normal blood flow through the valve
order in frequency of infection of valves
mitral > aortic> tricuspid> pulmonic
clinical syndromes acute symptoms
symptoms onset to dx ~ 1 week acute malaise shaking chills fever leukocytosis rheumatoid factor +
clinical syndromes subacute symptoms
symptoms onset to dx ~ 4 weeks weight loss, fatigue night sweats low grate temp normal WBC or leukopenia rheumatoid factor +
IBE clinical syndrome organism S aureus
common cause: IV drug abuse and patients with invasive lines
- acute onset with market symptoms
- rapid valve destruction
- CNS and or renal involvement
- moderate to high mortality rate
IBE clinical syndrome organism strep viridans
- usually slow growing with a 10+ day duration betwen symptoms onset and dx
- subacute presentation
- good prognosis with early dx and treatment
IBE clinical syndrome organism enterococcus
- from enterococcus faecalis
- elderly patients (usually men) undergoing procedure
- most have subacute presentation
- moderate mortality risk
physical exam findings
fever new or characteristically different murmur evidence of vasculitis or emboli -petechiae -splinter hemorrhages -roth spots -osler nodes -janeway lesions -CNS impairment -splenomegaly
dx of IBE duke major criteria
- positive blood cultures from at least two separate cultures drawn 12 hrs apart
- evidence of IE on echocardiogram
- new regurgitate murmur
dx of IBE duke criteria minor
- predisposing heart condition (MV prolapse, rheumatic or congenital heart disease)
- temperature
- presence of embolic disease of hemorrhage
- presence of immunologic phenomena
- positive blood culture but major criteria not met
- echocardiogram is positive but major criteria not met
IBE management
referrals:
infectious disease dr
cardiologist
cardiothoracic surgeon
IBE management indications for surgery
- mechanical valve
- bioprosthesis if:
- new paravalvular regurgitation or fistula
- sewing ring abscess or dehiscence
- organism ID
- blood cultures remain positive after 1 week
- embolism or major complication
absolute indications for surgery on a native valve
Intracardiac abscess or fistula
Left HF from severe regurg
Infection with Fungi or Resistant Gm-Neg bacteria
IBE pathophysiology
matastatic vegetation
Regurgitant jets from infected valve cause denuded endothelium in receiving chamber (wall or chordae) thrombus formation which also seeds with causative organism & proliferates into secondary vegetation.
Can occur on valve, supporting structures and/or mural endocardium
IBE pathophysiology abcess and fistula formation
Without treatment, organisms invade the valve annulus and/or adjacent myocardium.
Abscesses develop, fistulas may develop between sites
IBE pathophysiology
immune disease
Bacteremia typically persists over long periods of time
prolonged antigenic challenge to the immune system.
Some antibodies form immune complexes which activate complement that leads to microvascular damage: Impaired renal function; vasculitis/ skin lesions
IBE pathophysiology
systemic and pulmonary emboli
Small emboli are common with metastatic infection with embolizaton and possible abscess in BRAIN, kidney, liver, bone & frequently in the lungs.
Large emboli cause major vascular obstruction in BRAIN, spleen , liver, kidney & myocardium.
