valvular heart disease. learning objectives describe the etiology and clinical symptoms of acute...
TRANSCRIPT
Learning objectives
Describe the etiology and clinical symptoms of acute rheumatic fever.
Describe the pathology and natural history of acute rheumatic fever and rheumatic heart disease.
Describe an Aschoff body. Describe which parts of the heart are affected in
acute rheumatic fever. Describe the long-term consequences of rheumatic
fever. Describe the pathology and natural history of
chronic rheumatic heart disease, and know which valves are most often involved.
Describe the pathology of postrheumatic mitral stenosis.
Enlist the components of vegetation.
Rheumatic fever
Rheumatic fever is an acute immunologically mediated multisystem inflammatory disease that occurs a few weeks following an episode of group A streptococcal pharyngitis.
Acute rheumatic carditis, during active phase
May progress to Chronic rheumatic heart disease.
EtiopathogenesisAcute rheumatic fever is a hypersensitivity reaction induced by group A streptococci.
Antibodies against M proteins of certain strains of streptococci cross react with antigens in heart, joints and other tissues.
Genetic susceptibility is suggestedAutoimmune response to self antigens also suggested.
Chronic sequelae are a result of progressive fibrosis (healing process) and blood turbulance in valvular areas
Morphology
ACUTE RH. FEVER-- PancarditisPericarditis- serofibrinous/ Bread and butter type
Myocarditis Aschoff bodiesEndocarditis
Verrucous vegetations (1-2mm) at lines of closure of valves
Fibrinoid necrosis along cusps and teninous cords
MacCallum plaques in left atrium (Sub endocardial thickenings due to regurgitant jets)
Morphology of chronic RHD
Mitral valve is most often affected with rheumatic heart disease, followed by mitral and aortic together, then aortic alone, then mitral, aortic, and tricuspid together.
Mitral stenosis (99% cases)Fishmouth/ buttonhole stenosis
MicroscopyFibrosis/ scarringNeovascularization
Mitral valve as seen from above in the left atrium.
Typical "fish mouth" shape with chronic rheumatic scarring.
Mitral valve is most often affected with rheumatic heart disease, followed by mitral and aortic together, then aortic alone, then mitral, aortic, and tricuspid together.
Clinical features of ARF
The major clinical manifestations of ARF:
migratory polyarthritiscarditis, subcutaneous nodules, erythema marginatum, and Sydenham chorea.
Minor manifestations of ARF:Fever, arthralgias, Increased blood levels of acute phase reactants etc.
DIAGNOSIS
Jones criteria:Evidence of preceding group A strept. Infection
Presence of two major or one major and two minor manifestations
Clinical features of ARF
Age: 5-15 but may be in adultsTime: 10 days to 6wks after pharyngitis3% of pts effectedPrognosis of 1st attack good.
Clinical features of chronic rheumatic carditis
Valvular disease and its sequelae (yrs later)
MurmursCardiac hypertrophy, dilatation, heart failure
Arrythmias esp Atrial fibrillationThromboembolic complicationsInfective endocarditis
In the dilated atrium with a stenotic mitral valve, the blood stagnates. Hence, stasis is a factor in thrombogenesis..
Infection of heart valve or mural endocardium by a microbe leading to formation of bulky friable vegetations and destruction of underlying tissue.
Vegetations are composed of thrombotic debris and organisms
Classification
Acute Virulent organism Normal valve Necrotizing ulcerative, invasive infection Maybe fatal
Subacute Less virulent organism Damaged valve Treatable with antibiotics
Etiopathogenesis
ORGANISMSMost cases are bacterial although chlamydiae and ricketia also implicated
Damaged valves: Strept. Viridans (50-60%)
Normal/ damaged: Staph. Aureus (10-20%)I/V drug abusers: Staph. Aureus Prosthetic valves: Staph epidermidis
Others are enterococci, HACEK Culture negative: 10%
Etiopathogenesis
PREDISPOSED VALVESRHD (previously)Myxomatous mitral valve Degenerative calcific valvular stenosisProsthetic valves
HOST FACTORSImmunodeficiency, immunosupressionMalignancyDiabetesAlcoholI/V drug abuse
morphologyThe more virulent bacteria causing the acute bacterial form of infective endocarditis can lead to serious destruction, as shown here in the aortic valve. Irregular reddish tan vegetations overlie valve cusps that are being destroyed. Portions of the vegetation can break off and become septic emboli.