LMP299Y1 Lecture Notes - Rheumatic Fever, Rheumatism, Mitral Valve Stenosis

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3 Jun 2013
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CARDIAC IMMUNOPATHOLOGY
Type I hypersensitivity
Leads to cascae of degranulation of efector cells release of primary mediators causes smooth muscle
contraction activation of complement, kinins severe anaphalyctic reaction can cause significant acute
distress to someone, due to bronchial constriction and edeme when endothelial vessels become leaky
Heart primary
Not a big player with the heart but leaky blood vessels affected significantly in heart
Systemic anaphyalxix often medical emergency
Type 2 player in cardiac immunopathology
Directed against self-antigens cascade of changes including recruitment of inflammatory cells,
inflammation, tissue injury
Special form of type 2 hypersensitivity involved with rheumatic heart disease cross-reacting
antibodies develops antibodies against bacteria that cross react with self-antigens lead to tissue
damage in organs that express the self antigens
Antibody reaction against bacteria good but due to structure of antibody that develops antibody
reacts against self antigens in tissues
Type 2
Antibody-mediated transplant rejection = graft vascular disease
Lupus usually type 3
Pericardiotomy syndrome pericardioum is covering of the heart; otomy means cut in two; - antibody
reaction that develops when tissues of the heart are cut into
Post periocardiotomy syndrome congenital heart disease open heart surgey to correct the disease
metal wires that surgeons put in in order to do many of the more complicated congenital surgeries,
split the sternum, open the chest to expose the heart, repair, hen wire the sternum together using wire
Child had developed fever, pericarditis (inflammation of the heart covering felt as chest pain)
Inflammation of the pleura (lining of chest and lungs) occurs around two to four weeks after the
surgery
Immune system is reacting to antigens that are normally hidden from the immune system within the
tissues but with the disruption of the tissue by surgery or trauma or heart attack, those normally
hidden antigens are exposed and antibody readctions can develop against those
Post pericardiotomy syndrome
Pericardium was expanded due to fluid, not the enlarged heart leakage of fluid from vessels
surrounding heart fluid under pressure, accumulated in the sack to prevent heart from pumping
properly cause of death heart disease repair was fine, but accumulation of fluid that lead to
tamponade (pressure as result of accumulated fluid prevented heart from expanding and conracting
properly) if sack isn’t severe, there can be ongoing mild and moderate inflammation lead to scarring
(fibrosis) both the covering of the heart
Pathogenesis development of self-antigens
Type 4- cytotoxic or cellular mediated immune injury primary type of immunologic reaction that
occurs with cellular rejection of solid organs
Rheumatic fever occurs after infection with specific bacteria usual source of bacterial infection is
throat infection most common in throat, tonsillitis or pharyngitis
Rheumatic fever is mult-system but the heart takes the blunt of the pathology
In the US decline in the development of rheumatic fever in people in
Less virulent or disease-causing strains compared to before
But primarily, due to use of step A antibiotics
Mini-epidemics in various places
Can get strep bacteria, small percentage get the disease but very common bacteria, so still high
number of potential people develop the disease
Hypersensitivity reaction type 2 only certain serotypes of the group A streptococci are associated with
this rheumatic fever develops week and a half first child gets sore throat, takes a week and a half
for the rheumatic disease to develop group A strep components of bacteria that have the same
antigenic determinants that certain proteins that are present in the heart of mammals some similarity
with antigens in brain and joint tissues and skin but primarily the heart that has the most
Tropoyosin and myosin responsible for heart contracting
Rheuamatic fever bacteria itself responsible for
Latent period fits with the immune response explanation
Bacteria into the back of throat bacteria grow and cause local tissue damage and inflammatory
reaction get sore throat some bacteria get into lympathic drainage that drains into lymph nodes
gets into lymph node and incites immune reaction there, B cell reaction antibodies discharged from LN
get into blood stream aimed at attacking bacteria in throat they circulate through body attack
heart cell proteins because of matching antigen determinants shared between bacteria and heart
pericardium, myocardium, endocardium (pancarditis all inflammation of the heart all layers can be
affected)
Manifestations major ones
Carditis
Subcutaneous noduels painful bumps on skin
Marginatum rash
Syndenham chorea involvmenet of central nervous system in the brain uncontrolled movement of
arms and legs
Minor manifestations arthraligia is joint pain without swelling
Jones criteria some of these manifestations can occur without the patient having rheumatic fever
identification of minimal criteria that must be met for treatment strep A infection strict criteria
because the patient needs to be protected from strep A fever for the entire lifetime
In rheumatic fever, nearly all deaths due to involvmenet of heart
First phase called acute phase additional attacks
Chronic repeated recurrent attacks
Pathology non supportive = no pus is formed, so neutrophils not component of this injury initially, so
no pus-filled inflammatory areas which would be expected if bacteria is causing the issue
Inflammatory foci especially evident in the myocarditis
Pathogenesis initial antibody reaction to group A strep M protein
Antibodies produced corss react with antigens present in other cells type 2 reaction where antibody
mediated injury to the cell
Pericarditisi image
Pericardium usuall shiny
But inflammation, etc coats the heart so rough-looking
Aschoff body focus of inflammation has wavy pink stuff in background (fibrin), includes lymphocytes,
plasma cels, Aschoff yocytes and macropahges
Rheumatic endocarditis acute inflammation affecting the valves development of endocarditis
inflammation affecting valve tissue (third layer)
Endocarditis is the reason why primary cause for chronic rheumatic heart disease
Blood flow is turbulent called murmur
Myocardium pumping portion severly affected by inflammation it can fail, so heart failure
Can be significant disturbances in rythum of heart can be fatal
Possibility of developing tamponade leaky blood vessels of the three percent of people that get
rheumatic fever develop severe heart disease so jeopardize the lungs less severe damage, but focus
on cardiac valves
Recurrent episodes of acute and recurrent damage to structure (esp valves) response of body distorts
valve so they no longer work properly so chronic disease develops
Stenosis = narrowing
Tricuspid valve mostly on the left side
Normal heart blood from atrium blood ventricle which is main pumping
Valve tissue is transparent thin delicate looking
Mitral valve with disease left atrium at top; thick looking firm tissue chorade endonae instead of
being fine structs, they are thickened, they have fused, leaflet tissue is thickened valves do not work
properly do not open or close properly severe cases like this, fatal
Mitral stenosis
Stenosis blood backs up in heart and lungs do not flap
On the right side, opening between the leaflets of the valve normally the opening should the whole
circumference, but here, significantly narrower, leaflets do not bend
Example of artificial valve problems
1 disc breaks or the struts break
Aortic valve valve distorted and thickened
RHEUNMATIC FEVER IMPORTANT DISEASE
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