2.) what is the pathophysiology of rheumatic fever/ rheumatic heart disease?

2.) What is the Pathophysiology of Rheumatic Fever/ Rheumatic Heart Disease?

Organism Factors

• Based on evidence, ARF is exclusively caused by URTI ( Group A Streptococci).

• It has been postulated that a series of preceding streptococcal infections is needed to “prime” the immune system to the final infection that directly causes the disease.

The Immune Response

• Susceptible host encounters a group A streptococcus

• Auto immune reaction occurs• Leads to human tissue damage as a result of

cross-reactivity between epitopes on the organism and host.

Molecular mimicry

• Group A Streptococci- has epitopes present in the M protein

• Similar molecules – human myosin, tropomyosin, keratin, actin, laminin, vimentin, and NAG.

• Basis for Autoimmune response• T cell sensitization• T cells recalled following subsequent exposure

Valvular Damage

• Laminin- found in cardiac endothelium and is recognized by anti-myosin, anti-M protein, T cells.

• Antibodies to cardiac valve cross react with NAG

4.) What is the differential Diagnosis for the cause of Fever?

Infective Endocarditis

• Prototypic lesion- vegetation• Infection most commonly involves the heart

valve• Organisms that cause this generally enter the

bloodstream from mucosal surfaces, the skin, or sites of focal infection.

Infective Endocarditis

• Etiologies:– Health Care Associated – bacteremia arising from

IV catheterizations, nosocomial wound, UTI’s, chronic invasive procedures

– Prosthetic Valve endocarditis- intraoperative contamination

– Injection drug users-

Infective Endocarditis

• Highly variable clinical manifestations• Causative microorganism primarily responsible

for acute course incluse B-hemolytic streptococci, S. aureus, and Pneumococci.

• Febrile patient with valvular abnormalities or behavior pattern that predispose ( injection drug use)

• Bacteremia with organisms that frequently causes endocarditis

Infective Endocarditis

• 39.4-40 degrees Celcius fever for the acute course

• Fever may be blunted or absent in patients who are elderly or severely debilitated.