Carditis PDF

Dr/ Rasha Mokhtar Abdelkareem Lecturer of Pathology  After the lecture, students should be able to: I. Define rheumatic fever and discuss its etiology, pathogenesis, pathology and complications. II. Enumerate pathological types of pericarditis and its causes. Out...

Dr/ Rasha Mokhtar Abdelkareem Lecturer of Pathology  After the lecture, students should be able to: I. Define rheumatic fever and discuss its etiology, pathogenesis, pathology and complications. II. Enumerate pathological types of pericarditis and its causes. Outline the clinical features and complications of pericarditis. III. Outline the main types of endocarditis. Summarize the clinical features, pathogenesis and appearance of vegetation in each of these types. IV. Define myocarditis and cardiomyopathy and enumerate their types.   ANATOMY AND PHYSIOLOGY  The heart is a muscular pump that ejects blood into the vascular tree with sufficient pressure to maintain optimal circulation.  Heart is divided into four chambers: a right and a left atrium both lying superiorly, and a right and a left ventricle both lying inferiorly and are larger.  The blood in the heart chambers moves in a carefully prescribed pathway:  venous blood from systemic circulation → right atrium → right ventricle → pulmonary arteries → lungs → pulmonary veins → left atrium → left ventricle → aorta → systemic arterial supply  Definition: Rheumatic fever (RF) is an auto-immune collagen disease characterized by an inflammatory changes in the fibrous tissue of different body organs specially the heart, joints, subcutaneous tissue, blood vessels, and CNS.  Incidence:  Common in children and young adults, between 5-15 years, rare before the age of 3 years.  Girls are affected more than boys.  There is a strong individual predisposition.  Its incidence has declined in the developed countries as a result of improved living conditions and early use of antibiotics in streptococcal But it is still common in the developing countries of the world.  Predisposing factors:  Overcrowding,  damp weather,  poor housing and low socioeconomic conditions. These factors predispose to upper respiratory tract infections with subsequent development of RF.  Etiology:  RF is a febrile illness follows a streptococcal pharyngitis and/or tonsillitis caused by group A of ß- hemolytic streptococci.  RF develops after a latent period of 2-4 weeks (after recovery from infection).  Only a small number of patients with streptococcal infection develop an attack of RF.  The bacteria are neither found in the lesions nor in the blood stream.  RF tends to recur after subsequent attacks of streptococcal pharyngitis and each recurrence increase the risk of serious valvular diseases.  Treatment of streptococcal pharyngitis does not abolish the risk of subsequent RF.  Long term administration of penicillin prevents further attacks of streptococcal pharyngitis and of subsequent RF.  Pathogenesis  Rheumatic fever is a systemic disease affecting the connective tissue around arterioles.  Streptococci pyogenes and myocardium shares common antigens. 1. A susceptible host, on being encountered with group A Streptococcus infection, mounts an autoimmune reaction by formation of autoantibodies against bacteria. 2. These autoantibodies cause damage to human tissues due to cross-reactivity between epitopes in the components of bacteria and the host. 3. Streptococcal epitopes present on the bacterial cell wall, cell membrane and the streptococcal M protein, are immunologically identical to human molecules on myosin, keratin, actin, laminin, vimentin and N- acetylglucosamine. 4. Molecular mimicry and cross-reactivity between streptococcal M protein in particular and the human molecules forms the basis of autoimmune damage to human target tissues in RHD i.e. cardiac muscle, valves, joints, skin, neurons etc. Rheumatic fever  MORPHOLOGIC FEATURES A. Cardiac Lesions  RHEUMATIC PANCARDITIS Although all the three layers of the heart are affected in RF, the intensity of their involvement is variable.  1. Pericarditis:  Grossly,  there is loss of normal shiny pericardial surface due to deposition of fibrin  If the parietal pericardium is pulled off from the visceral pericardium, the two separated surfaces are shaggy due to thick fibrin covering them. This appearance is often likened to ‘bread and butter appearance’.  healing by fibrosis lead to: Adhesion of both parietal and visceral pericardium and adhesion of pericardium to mediastinal tissue  White fibrotic areas milk spots  Microscopically, fibrin is identified on the surfaces. The subserosal connective tissue is infiltrated by lymphocytes, plasma cells, histiocytes and a few neutrophils..  2. Myocarditis:  Grossly,  in the early (acute) stage, the myocardium, especially of the left ventricle, is soft and flabby.  In the intermediate stage, the interstitial tissue of the myocardium shows small foci of necrosis.  Later, tiny pale foci of the Aschoff bodies may be visible throughout the myocardium.  Microscopically, the most characteristic feature is the presence of distinctive Aschoff bodies.  Aschoff bodies are composed of swollen eosinophilic collagen surrounded by lymphocytes and macrophages and Aschoff cells.  The larger macrophages may become Anitschkow cells or Aschoff giant cells with two or three nuclei or a single convoluted nucleus.  With time the Aschoff bodies subside and healing by fibrosis occurs, leaving minute scars in the CT of the myocardium.  3. Endocarditis:  Involve the valvular and mural endocardium, causing rheumatic valvulitis and mural endocarditis, respectively.  Rheumaticvalvulitis is chiefly responsible for the major cardiac manifestations in chronic RHD.  Inacute RF, the most prominent endocardial lesion consists of thrombotic vegetations forming a line of multiple, fine, adherent, grey pink, firm, nodular deposits 1-3mm on the surface of the valve cusps.  Theyform mainly on the line of contact between the cusps when the valves close.  Similar vegetations form on the chordae tendinae.  Aschoff bodies develop and are particularly numerous in the posterior wall of the left atrium & also seen on the valves.  Healingmay result in thickening and irregularity of the endocardium in this area McCallum’s patch.  Microscopically:  Involvement of the endocardium typically results in fibrinoid necrosis and wart formation along the lines of closure of the left-sided valves of the heart.  Thereis also an inflammatory edema, infiltration by polymorph, lymphocytes, macrophages and focal fibrinoid necrosis.  Focal ulceration occurs and acute thrombotic vegetation are formed in these areas.  There is an ingrowth of capillaries from the base of the valves, followed by organization of vegetations.  Organization of vegetations results in fibrous union between adjacent cusp margins → valve stenosis.  Organization of vegetations on the chordae tendinae leading to their becoming matted together → shortening of the chordae and distortion of the cusps → valve incompetence → regurgitation.  Withrecurrent acute attacks, injury of the valves becomes more severe and further fibrous thickening and deformity results.  Inchronic RF both the mitral and aortic valves are affected in 50% of cases, and the mitral valve alone in about 25% of cases.  The mitral, aortic and tricuspid valves are involved in about 15% of cases, while involvement of all 4 valves or of the aortic valve alone is rare.  Thevalves of the right side of the heart are never affected alone. location of vegetations in rheumatic endocarditis  Joints:  Fleeting arthritis; one joint is affected after the other, occurs specially in large joints.  Joint cavity shows serous exudate; joint effusion.  Synovial, capsular and pericapsular tissues (tendons and their sheaths) show congestion, edema, cellular infiltrate of histiocytes, lymphocytes, plasma cells and scanty Aschoff bodies.  Articular cartilage is not affected, so with resolution of inflammation complete restoration of the joint functions occur.  Subcutaneous nodules: 1. It develops over bony prominences or tendons of the arms and legs, elbow, wrist, spine, occipital protuberance in severe cases. 2. The nodules are between 1 and 2 cm in diameter, painless and resemble enlarged Aschoff bodies.  Erythematous skin rashes may occur; “erythema marginatum”. It is a long-lasting reddish rash that begins on the trunk or arms as macules, which spread outward and clear in the middle to form rings, which continue to spread and coalesce with other rings  Brain:  Edema, thrombosis, hemorrhage and perivascular round cell infiltration occur in the basal ganglia and cerebral cortex.  Itcauses sudden, involuntary, irregular, purposeless, rapid movements particularly of the extremities called “Sydenham's chorea” with muscular in-coordination and weakness. A. Major criteria: B. Minor criteria: 1. Carditis 1. Fever 2. Polyarthritis 2. Arthralgia 3. Chorea (Sydenham’s chorea) 3. Previous history of RF 4. Erythema marginatum 4. Laboratory findings of 5. Subcutaneous nodules elevated ESR, raised C-reactive protein, and leucocytosis 5. ECG finding of prolonged PR interval. Complication of rheumatic fever :  Repeated attacks cause damage to the heart in the form of: 1. valvular stenosis or incompetence, 2. myocardial fibrosis 3. pericardial adhesions ending in congestive heart failure. 4. Subacute infective endocarditis may complicate chronic rheumatic valvulitis.  The most serious effect is rheumatic myocarditis → various degrees of acute HF.  Causes of death: A. Heart failure: from active carditis or secondary to chronic rheumatic valvulitis. B. Embolic manifestation: from atrial or vascular thrombosis. It causes death in 20-35% of cases. C. Bacterial endocarditis: causes death in 10-15% of cases. D. Pneumonia: in congested lungs.  Def: inflammation of pericardium  Types: 1. Fibrinous (Serofibrinous) Pericarditis 2. Suppurative Pericarditis  Fibrinous (Serofibrinous) Pericarditis: Caused by the following diseases: (1)Rheumatic fever is the commonest cause. (2)Complicates lobar pneumonia and bronchopneumonia. (3)Tuberculous pericarditis. (4)Over myocardial infarction. (5)A terminal complication in uraemia and diabetes mellitus.  Suppurative Pericarditis: Is caused by: (1) Streptococcus, staphylococcus, and meningococcus septicaemia. (2) Blood and lymphatic spread from pneumococcal infection of the lung. (3) Direct spread from empyema, osteomyelitis of the ribs, sub-phrenic abscess or liver abscess. (4) Penetrating chest wounds. Pathology: Suppurative inflammation with pus accumulation in the pericardial sac.  Complication: If the patient survives, the lesion heals by organization causing pericardial adhesions, constrictive pericarditis or adherent mediastino- pericarditis. Adherent Mediastino-pericarditis: Fibrous adhesions between the parietal pericardium and adjacent mediastinal structures, pleura, diaphragm and thoracic cage. Constrictive Pericarditis: Dense adhesions between the two layers; of the pericardium with partial or complete obliteration of the pericardial sac.  Thelesion limits the diastolic expansion of the heart and constricts the orifice of the venae cava causing chronic general venous congestion.  TYPES OF ENDOCRADITIS 1. INFECTIVE 2. Non-Infective ENDOCARDITIS Endocarditis: a. Acute infective endocarditis (AIE or ABE). a. Rheumatic endocarditis. b. Atypical verrucous endocarditis (Libman-Sacks b. Subacute infective endocarditis). endocarditis (SIE or SBE). c. Non infective thrombotic endocarditis (Terminal endocarditis)  Aetiology: Causative organisms: Virulent bacteria e.g. streptococcus haemolyticus, staphylococcus aureus, pneumococci and gonococci.  Pathogenesis:  Acute infective endocarditis is a part of a septicaemia.  The source of bacteria is a septic focus in the body as puerperal sepsis, acute Osteomyelitis, carbuncle, pneumonia.  Bacteria reach the heart by the blood stream and attack the healthy valve.  Pathology: (1) The valves commonly affected are the mitral and aortic. (2) The affected valve shows suppurative inflammation with ulceration and perforation of the cusps. (3) Bulky septic vegetations develop on the surfaces of the inflamed cusps, cordae tendinae and mural endocardium. They are friable and yellow in color.  The vegetations consist of fibrin, platelets, bacterial colonies and acute inflammatory cells in the form of polymorphonuclear leucocytes and pus cells. (4) Fragmentation of the vegetations gives rise to septic emboli which cause pyaemic abscesses.  The disease terminates by death in 1-2 month due to the resulting valve incompetence and the severe bacterial infection  Aetiology: Causative organisms: It is caused by bacteria relatively of low virulence. The most important is “viridans” group of α- hemolytic streptococci. Rarely haemophilus influenza, E. coli and other bacteria.  Pathogenesis: The organisms enter the blood stream from dental sepsis and throat infections during mastication, dental extraction and tonsillectomy (Bacteraemia). They invade valves predisposed to infection by: (a) Chronic rheumatic valvulitis. (b) Congenital malformations as bicuspid aortic valve, pulmonary stenosis, septal defects... etc.  Pathological Lesions: I. Cardiac Lesions: (1) Vegetations develop mainly on the mitral and aortic valves as they are the valves commonly affected by rheumatic valvulitis. The vegetations are bulky, polypoid, friable and easily detached. They are grey, reddish or brown in color. Vegetations develop on any surface of the cusps, cordae tendinae and may extend over the posterior wall of the left atrium over the MacCallum’s patch. Microscopically: the vegetations show: (a) A top layer of platelets and fibrin covering colonies of bacteria. (b) A base of granulation tissue infiltrated by macrophages, further down it changes into fibrous tissue which blends with the cusp substance. (2) The myocardium shows cloudy swelling and fatty degeneration due to toxaemia. Endocarditis of the mitral valve (subacute, caused by Streptococcus viridens). vegetations are denoted by arrows. II. Embolic Lesions: Vegetations fragment and form emboli causing: (1) Infarcts: In the spleen, kidney and brain. (2) Retinal necrosis and blindness: Due to embolism in the retinal artery. (3) Coronary artery embolism: Rare. (4) Mycotic aneurysms: Occur commonly in the cerebral and mesenteric arteries, rarely elsewhere. (5) Focal embolic glomerulonephritis: Few of the glomerular capillaries show thrombosis and necrosis with leakage of the red cells into the Bowman’s space causing haematuria. Grossly the surface of the kidney shows reddish spots “flea-bitten kidney”.  Skin lesions:  Splinter hemorrhage and Osler’s nodes. These appear as small raised painful nodules, mainly in the extremities.  Clubbing of the fingers III. Toxic Lesions: (1) Fever, anaemia, leucocytosis and clubbing of the fingers. (2) Degeneration in the liver and kidney and enlargement of the spleen. Course: (1) Termination in congestive heart failure within 6-18 months. (2) With antibiotics the vegetations undergo organization, fibrosis, calcification. Disturbance in the valvular function may cause failure. FEATURE Acute bacterial endocarditis. Subacute bacterial endocarditis. 1. Duration 6 weeks 2. Most common Staph. aureus, Streptococcus organisms b-streptococci viridans 3. Virulence of Highly virulent Less virulent organisms 4. Previous condition Usually previously Usually previously of valves normal damaged 5. Lesion on valves Invasive, destructive, Usually not invasive suppurative or suppurative 6. Clinical features Features of acute Splenomegaly, systemic infection clubbing of fingers, Petechiae  Atypicalverrucous endocarditis is a manifestation of collagen diseases. Vegetations are small, granular and multiple. Œ Non-bacterial thrombotic endocarditis is an involvement of the heart valves by sterile thrombotic vegetations, often preceded by hypercoagulable state.  Definition:  It is an inflammation of the myocardium, which occurs as a result of: a) Direct involvement by the causal agents. b) Toxin-mediated injury. c)A local hypersensitivity reaction.  The commonest causes are viral.  Types: 1. Viral interstitial myocarditis 2. Suppurative myocarditis 3. Toxic myocarditis 4. Hypersensitivity reactions 5. Granulomatous myocarditis  A heterogenous group of disorders, in which there is chronic myocardial dysfunction of uncertain cause.  Cardiomyopathy is classified as hypertrophic, dilated and restrictive.  They may be further divided into:  primary types of unknown etiology, and confined to the myocardium  secondary types which occur with some systemic disorders.