Rheumatic Fever & Endocarditis PDF
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Hadhramout University College of Medicine and Health Science Medical Laboratory Science Department
Salim Bafakeer
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Summary
This presentation covers rheumatic fever and endocarditis, including pathogenesis, clinical manifestations, and morphology. The material is oriented toward a professional medical audience.
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RHEUMATIC FEVER AND RHEUMATIC HEART DISEASE Prof. Salim Bafakeer MD pathology RHEUMATIC FEVER A acute, immunologically mediated, post-streptococcal non- suppurative, multisystem inflammatory disease; principally affecting the heart, joint...
RHEUMATIC FEVER AND RHEUMATIC HEART DISEASE Prof. Salim Bafakeer MD pathology RHEUMATIC FEVER A acute, immunologically mediated, post-streptococcal non- suppurative, multisystem inflammatory disease; principally affecting the heart, joints, central nervous system, skin and subcutaneous tissues.. Occurs 1-5 weeks after an episode of pharyngitis caused by group A β-hemolytic streptococcal infection. Most common in children; 5-15 years old. Tissue lesions are sterile (i.e. contain no streptococci) Recurrent acute RF is always preceded by a streptococcus infection Pathogenesis It is a post-infectious immunologic disease results from immunologic reactivity to streptococcal antigens that evoke antibodies which cross reach with human tissue antigen Antigens involved: Cell wall polysaccharide of group A streptococcus: forms antibodies cross reactive with cardiac valves. Cell wall M protein showed cross reactivity with sarcolemma & myosin of cardiac muscle. Hyaluronate capsule of group A streptococcus is identical to human hyaluronate present in joint tissues In brain autoantibodies target the basal galnglia and dopaminergic neurons. Pathogenesis Clinical manifestations Cardiac: Pancarditis (inflammation of endocardium, myocardium and pericardium) Extracardiac: Fever Arthritis Arthralgia Skin lesions Chorea. JONES' CRITERIA FOR DIAGNOSIS (Need 2 major, or 1 major and 2 minor) Major Manifestations: Carditis. Arthritis (migratory polyarthritis) Chorea Subcutaneous nodules Erythema marginatum Minor Manifestations: Clinical: Fever , Arthralgia; History of rheumatic fever or rheumatic heart disease Laboratory: Acute phase reactants (ESR, C-reactive protein, leukocytosis) Prolonged P-R interval on ECG Supporting Evidence of Strep. infection (not major or minor). Increased titer of Streptococcal antibodies Positive throat culture for group A Strep. Recent scarlet fever Morphology Acute phase of rheumatic fever: Characteristic lesions are Aschoff's nodules: Foci of fibrinoid necrosis (representing the site of antibody- antigen reaction) Surrounded by lymphocytes, macrophages, and occasional plasma cells Plump "activated" histiocytes called Anitschkow's or Aschoff cells: caterpillar cells with abundant cytoplasm and central round nuclei; some are multinucleated. These foci may be found in the pericardium, myocardium, or in the valves. They ultimately "heal" by fibrosis. Microscopic appearance of an Aschoff body: spherical or fusiform microscopic structures, showed central necrosis surrounded by collection of lymphocytes (primarily T cells), scattered plasma cells, and activated macrophages The Anitschkow cells have abundant cytoplasm and nuclei with centrally condensed chromatin as wavy ribbon (so called “caterpillar cells”) Pancarditis Pericarditis: Aschoff nodules form in pericardium May cause pericardial effusion Exudate is usually serous with little fibrin or PMN component Myocarditis: Aschoff nodules develop in myocardium. Interstitial oedema and mild inflamamtion Usually mild, but can cause left ventricular failure Endocarditis: Aschoff nodules form --> slight irregularity of surface Aggregation of fibrin and platelets forming small (1-3 mm) vegetations called "verrucae" along the lines of closure of the valve leaflets. Aortic and mitral most prone to develop severe lesions Acute rheumatic mitral valvulitis: Small vegetations are visible along the line of closure of the mitral valve leaflet; fibrous thickening and fusion of the chordae tendineae. Aschoff nodules" seen in myocardium. These are centered in interstitium around vessels Extracardiac: Joints: Effects large joints (e.g. knee) Joint pain stops with aspirin 90% of adults. Transitory from joint to joint No sequelae Syndenham's Chorea (chorea = involuntary dance like movements): Insidious onset Restless, fidgety, cannot keep still Involuntary movements, disappear during sleep Element of emotional instability Subcutaneous nodule: painless nodules beneath the skin on the extensor surface of elbow and wrist joints. Occur in children and last for 4 to 6 days unlike rheumatoid nodules which may persist for months or years and may be painfull and tender. Erythema marginatum: flat or slightly raised, painless erythematous rash with pale centers and rounded or serpiginous margins Death due to acute rheumatic fever is rare, but does occur because of: Myocarditis--> arrhythmias (e.g. atrial fibrillation--> thrombus --> embolus) Left ventricular dilatation --> heart failure Pericarditis (restrictive heart failure) Chronic rheumatic heart disease Permanent valve deformity due to post-inflammatory fibrosis May occur 10-30 yrs after repeated attacks of acute RF 70% have just mitral involvement; 25% have both mitral and aortic involvement Endocarditis heals by progressive fibrosis Fibrosis of valve leaflets --> stenosis Fibrosis of chordae tendonae --> regurgitation RHEUMATIC HEART DISEASE (RHD) Characteristically, valve cusps and leaflets become permanently thickened and retracted, often with fusion Secondary deposition of Ca++ Fibrous bridging across the valvular commissures and calcification create a Fish mouth (buttonhole) stenosis. Microscopic: shows neovascularization and diffuse fibrosis that obliterates the normal leaflet architecture. No Aschoff bodies Long-term Outcome of RHD Depends on severity of chronic valve changes May develop heart failure due to mitral stenosis, mitral incompetence or mixed mitral valve disease. Infective endocarditis Left atrial thrombus formation Endocarditis Types of endocarditis: Non-infective (Non-microbial): Rheumatic heart disease. Libman-Sacks Endocarditis (systemic lupus) Non-bacterial thrombotic -NBTE Infective (Microbial) Mainly bacterial or fungal (viral, rickettsial rare) Destroys valve tissue Nonbacterial Thrombotic Endocarditis (NBTE) Characterized by the deposition of small (1 to 5 mm), sterile thrombi on the leaflets of the cardiac valves Occur on mitral, and less often aortic and tricuspid valve Typically occurs in hypercoagulable state (e.g. deep venous thrombosis). Common in debilitated patients (cancer or sepsis) Frequently associated with advanced cancer especially mucinous adenocarcinomas Microscopically: Composed of sterile, bland vegetations Do not cause tissue destruction. Does not show any inflammatory infiltrate Nonbacterial thrombotic endocarditis (NBTE): (A) row of thrombotic vegetations along the line of closure of the mitral valve leaflets. (B) showing bland thrombus, with virtually no inflammation Endocarditis of Systemic Lupus Erythematosus (Libman-Sacks Endocarditis) It occurs in about 10% of patients with SLE, The lesions develop as a consequence of immune complex deposition Occur most frequently on the mitral and tricuspid valves The lesions are small (1–4 mm in diameter) single or multiple, sterile Pink vegetations that often have a warty (verrucous) appearance. Microscopically: composed of fibrin and platelet thrombi. The endocardium underlying the verrucae shows fibrinoid necrosis, proliferation of capillaries infiltration by histiocytes, plasma cells, lymphocytes, neutrophils Infective endocarditis (I.E) It is a microbial infection characterized by colonization or invasion of the heart valves or the mural endocardium This leads to the formation of vegetations composed of thrombotic debris and microorganisms, often associated with destruction of the underlying cardiac tissues. Infective endocarditis is classified into: Acute endocarditis (ABE) Subacute endocarditis (SABE) Pathogenesis Bacteria entering the bloodstream are implanted on the cardiac valves or mural endocardium because they have surface adhesion molecules which mediate their adherence to injured endocardium The circulating bacteria are lodged much more frequently on previously damaged valves, chiefly RHD and congenital heart disease, than on healthy valves. Conditions producing haemodynamic stress on the valves are liable to cause damage to the endothelium, favoring the formation of platelet thrombi which get infected from circulating bacteria Infective endocarditis Sub-acute bacterial endocarditis: Previously damaged valve causative agents: poorly virulent (e.g. Streptococcus viridans) pathogenesis: abnormal valve --> platelet-fibrin deposits, thrombotic vegetations on valves bacteraemia --> organisms invade thrombotic vegetations --> slowly proliferate --> gradual valve destruction - Acute infective endocarditis: patients with normal valves causative agents: highly virulent (e.g. Staphylococcus aureus) pathogenesis: bacteraemia --> organisms invade heart valve --> rapidly proliferate --> necrosis and valve destruction --> thrombotic vegetations. Acute infective endocarditis development depends on: virulence of organism bacterial numbers (i.e. is the bacterial invasion sufficiently large) resistance of host Risk factors Rheumatic heart disease Congenital malformations. Other cardiac malformations Mitral valve prolapse Degenerative calcific valvular disease Iatrogenic Prosthetic valves Indwelling catheters (may cause sub-acute or acute form) Immunocompromised patients may sometimes be predisposed to bacterial endocarditis (often the acute pattern): Neutropenia AIDS Immunosuppression IV drug users are at a high risk of acute infective endocarditis by nature of their habit Morphology Macroscopic: Friable (easily disintegrates), bulky, bacterial laden vegetations on heart valve Vegetations may be single or multiple Vegetation size varies from a few millimetres to centimetres Aortic valve showed a large, irregular, reddish tan vegetation Irregular reddish tan vegetations overlie valve cusps that are being destroyed. Microscopic: Acute endocarditis: Vegetations tend to be bulkier Vegetations occur on normal valves Invasion may cause perforation or erosion of underlying valve leaflet, and may spread to form abscesses in the myocardium Subacute endocarditis: Vegetations tend to be smaller Vegetations occur on structurally abnormal valves Invasion does not tend to cause perforation or erosion of underlying valve leaflet, but often extend onto the adjacent mural endocardium Infective endocarditis: friable vegetations of fibrin and platelets (pink) mixed with inflammatory cells and bacterial colonies (blue). Complications of I.E Cardiac: Valvular insufficiency (leading to volume overload) Myocardial abscess with possible perforation of IV septum (causing left-right shunting) or free wall (causing tamponade) Suppurative pericarditis Dehiscence (dislodgement) of artificial valve Embolic: Left sided lesions Infarcts of brain, spleen, kidneys, limbs, etc. Less commonly, mycotic aneurysms occur (bacterial thrombus lodges in vessel, and doesn't occlude, but instead weakens the wall which may lead to an aneurysm, which may rupture) Right sided lesion - lung Diagnosis Clinical suspicion based on knowing risk factors and for patients with unexplinaed fever, septicaemia, heart failure and embolic infarct Suspicion raised when investigations reveal: Raised ESR Raised white cell count Normochromic, normocytic anaemia Investigations specifically undertaken to diagnose include: Blood culture will show organism (provided no antibiotics are being taken and infection is not fungal) Echocardiogram may show vegetation Prophylaxis: use of antibiotics in patients with some form of cardiac abnormality who is about to have dental or surgical procedures Major forms of vegetative endocarditis INFECTIVE NBTE LIBMAN- RHEUMATIC SACKS Mitral; aortic; Mainly mitral; Frequently Mitral alone; Valves common combined less on aortic Mitral & mitral and aortic affected mitral &aortic and tricuspid tricuspid combined along the line of along the line on both along the line of Location on closure, extend of closure surfaces of closure valve onto adjacent valve structures Often large, grey- Small bland Small to Small, warty, Pathology to greenish, nondestructive Medium-sized, inflammatory irregular; often vegetations inflammatory vegetations, destructive vegetations; generally produce heal with permanent scarring. deformity very common very common Less common Less common Embolization Thank you