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Transcript
The Pathology of Myocardial Diseases (1) Cardiomyopathy – Defined as “heart muscle disease of unknown cause,” generally referred to as primary or idiopathic cardiomyopathy, (2) Specific heart muscle disease – defined as “heart muscle disease of known cause or associated with disorders of other systems. Myocardium Cardiomyopathies The clinical picture is largely determined by one of the following three clinical, functional, pathologic patterns, each of which can have either a known or an unknown cause: Dilated Cardiomyopathy (90%) Hypertrophic Cardiomyopathy Restrictive Cardiomyopathy Myocardium Dilated Cardiomyopathy (DCM) Etiology of the DCM : – 1. Primary (Idiopathic) (30%) DCM – 2. Secondary DCM Myocardium 1. Primary (Idiopathic) dilated cardiomyopathy Characterized by the gradual development of cardiac failure associated with four-chamber hypertrophy and dilatation of the heart of unknown cause. Familial occurrence (approximately 20% of cases) – autosomal dominant, autosomal recessive, and X-linked inheritance Genetic syndromes: – Friedreich's ataxia – Duchenne's-Becker's muscular dystrophy Myocardium Pathophysiology Apoptosis, or programmed cell death, has been reported in clinical and experimental dilated cardiomyopathy, which is characterized by – depressed systolic function or systolic pump failure – cardiomegaly – ventricular dilatation Reduced left ventricular contractile force leads to decreased cardiac output, resulting in increased residual volumes in end-systole and end-diastole. Myocardium Usually affects those 20 to 60 years old Slowly develops Fifty percent of patients die within 2 years – only 25% of patients survive longer than 5 years Death is usually attributable to – progressive cardiac failure and/or – arrhythmia Embolism from dislodgement of an intracardiac thrombus may occur Myocardium Secondary dilated cardiomyopathies – Alcoholism – Chemicals&Drugs Heavy metals Emetine Doxorubicin Cocaine Methamphetamine Cobalt – High output states Anemia Thyrotoxicosis Pregnancy – HIV and other infections Viral endocarditis/myocarditis Parasites Protozoa Chagas disease (most common cause in parts of South America) – Collagen vascular disease – Glycogen storage disease – Thiamine deficiency and zinc deficiency – Hypophosphatemia – Amyloidosis – Neuromuscular disorders Myocardium Pathology The heart is usually heavy – Weighing two to three times normal, – Flabby (usually with dilatation of all chambers) Nevertheless, because of the wall thinning that accompanies dilatation, the ventricular wall thickness may be less than, equal to, or more than normal. Mural thrombi are common – particularly near the apex of the left and right ventricles and in the atria thromboembolism Mitral regurgitation, when present, is primarily a result of left ventricular chamber dilatation (functional mitral regurgitation). Myocardium The left ventricle often has patchy myocardial (mostly subendocardial) fibrous scars The sizes of individual muscle cells vary; The nuclei are usually enlarged throughout, indicating hypertrophy. Myocardium Complications – Heart failure – Volume overload – Pulmonary edema – Hypoxia – Cardiogenic shock – Death Myocardium Arrhythmogenic Right Ventricular Cardiomyopathy (Right ventricular Dysplasia) Familial disorder Progressive nature of the lesion with apoptosis Sudden death in vigorous good health – right-sided and sometimes left-sided heart failure – rhythm disturbances (particularly ventricular tachycardia) Morphology – the right ventricular wall is severely thinned, extensive fatty infiltration loss of myocytes interstitial fibrosis Myocardium Hypertrophic Cardiomyopathy (HCM) Hypertrophic cardiomyopathy is also known by such terms as Synonyms: – – – – – idiopathic septal hypertrophy asymmetric septal hypertrophy Les Aspin's disease Reggie Lewis's disease muscle-bound heart A genetic basis in many cases Myocardium It is characterized by a heavy muscular hypercontracting heart, in striking contrast to the flabby, hypocontracting heart of dilated CM. In contrast to the hypertrophy induced by the increased workload of valvular, hypertensive, ischemic, and congenital heart diseases, that observed in Hypertrophic CM develops progressively in the absence of an identifiable extrinsic inciting stress. Myocardium End-stage heart failure can be accompanied by dilatation. The major problems in HCM are: – atrial fibrillation with mural thrombus formation, – embolization from the mural thrombi, – infective endocarditis on the mitral valve, – intractable cardiac failure, – sudden death (most common cause of death and particularly likely in young males with familial HCM or with a family history of sudden death). Myocardium Morphological findings The essential anatomic feature of HCM is massive myocardial hypertrophy. The classic pattern is said to be disproportionate thickening of the ventricular septum as compared with the free wall of the left ventricle (with a ratio greater than 1.3), frequently termed asymmetric septal hypertrophy. Myocardium Restrictive Cardiomyopathy (RCM) Restrictive cardiomyopathy can be idiopathic or secondary to a heart muscle disease that manifests as restrictive physiology. The common hemodynamic disturbance is impairment of ventricular filling due to the thickening and increased rigidity of the endocardium and myocardium secondary to infiltration by amyloid or by fibrosis. Myocardium Systolic function remains normal or near normal until late stages. Most older people get some amyloid in their atria and aortas. If amyloid involves the myocardium extensively, the muscles cannot contract. This is the usual cause of "restrictive cardiomyopathy". Myocardium Etiology: – Idiopathic restrictive cardiomyopathy Loeffler eosinophilic endomyocardial disease – Secondary restrictive cardiomyopathy Hemochromatosis Amyloidosis Sarcoidosis Progressive systemic sclerosis (scleroderma) Carcinoid heart disease Glycogen storage disease of the heart Myocardium MORPHOLOGY: – the ventricles are of approximately normal size or slightly enlarged – the cavities are not dilated – the myocardium is firm – biatrial dilatation (common) Microscopically there is patchy or diffuse interstitial fibrosis/amyloid. Myocardium Specific Heart Muscle Disease Cardiac infections Viruses – – – – – coxsackievirus ECHO influenza HIV CMV Chlamydia (C.psitacci) Rickettsia Bacteria – Corynebacterium – Neisseria – Borrelia Fungi (Candida) Protozoa – Trypanosoma – Toxoplasma Helminth (Trichinosis) Myocardium Toxic substances Alcohol Cobalt Cathecolamines CO Lithium Hydrocarbons Arsenic Cancer chemotherapy Myocardium Metabolic causes Hyperthyroidism Hypothyroidism Hypokalemia Hyperkalemia Hypoproteniamia, Hypovitaminosis(thiamin e) Hemochromatosis Myocardium Neuromuscular disease Friedreichs ataxia Muscular dystrophia Congenital atrophies Stroge disorders Hunter-Hurler syndrome Glycogen storage disease Amyloidosis Myocardium Infiltrative diseases Leukemia Carcinomatosis Sarcoidosis Radiation-induced fibrosis Immun-mediated reactions Myocarditis Post-transplant rejection Myocardium Myocarditis Myocarditis is an uncommon disease that is characterized by inflammation of the heart; – leukocytic infiltrate – resultant nonischemic necrosis – degeneration of myocytes Subsequent myocardial destruction often leads to a dilated cardiomyopathy. Most cases of well-documented myocarditis are viral in origin. Myocardium Etiology of Myocarditis Infectious agents - Viruses (Coxsackievirus(B), Advenovirus, Echovirus, EBV, Hepatitis C, HHV, HIV, CMV, Influenza, Measles, Mumps, Rubella, Varicella) - Chlamydia (C.psitacci) - Rickettsia (R. rickettsii, R. tsutsugamushi) - Bacteria (Corynebacterium, Neisseria, Borrelia, Klebsiella, Leprospira, Cocci, Clostridia, Treponema, Brucella, Salmonella) - Fungi (Candida, Actinomycosis, Coccidioidomycosis, Histoplasmosis) - Protozoa (Trypanosoma cruzi, toxoplasma, amebiasis) - Other parasites (Toxocara canis, Schistosomiasis, Heterophyiasis, Cysticercosis, Echinococci, Visceral larva migrans. Myocardium Immun-mediated reactions - Post-transplant rejection - Medications Drugs – Hypersensitivity myocarditis is observed with a variety of medications (eosinophilic infiltrate of the myocardium) – A direct cytotoxic effect on the myocardium - penicillin, ampicillin, hydrochlorothiazide, methyldopa, sulfonamide - lithium, doxorubicin, cocaine, numerous catecholamines, acetaminophen, cyclophosphamide, tetracycline, isoniazid, phenytoin, ect. Myocardium Chemicals Systemic diseases Lead Arsenic Carbon monoxide Scorpion envenomations Autoimmune diseases ( SLE, Scleroderma, Rhematoid arthritis) Sarcoidosis Giant cell myocarditis SLE Giant cell arteritis Dermatomyositis Ulcerative colitis Radiation therapy (dilated cardiomyopathy) Myocardium It may occur at any age The vulnerable ones... – infants – immunosuppressed individuals – pregnant women Myocardium A Specific type of Myocarditis: Chagas’ disease Caused by a protozoa: Trypanosoma cruzi Although uncommon in the northern hemisphere, Chagas’ disease affects up to onehalf of the population in endemic areas of South America. Myocardial involvement is found in approximately 80% of infected individuals. Myocardium Trichinosis The most common helminthic disease with associated cardiac involvement. Corynebacterium diphtheriae Traditionally considered a myocarditis, injury to the myocardium by the potent exotoxin of the bacterium Corynebacterium diphtheriae is characterized by patchy myocyte necrosis with only a sparse lymphocytic infiltrate. Myocardium HIV myocarditis Myocarditis occurs in many patients with acquired immunodeficiency syndrome (AIDS). Two types have been identified: – (1) inflammation and myocyte damage without a clear etiologic agent – (2) myocarditis caused directly by HIV or by an opportunistic pathogen Myocardium Morphology During the active phase of myocarditis, the heart may appear normal or enlarged with dilatation of either ventricle or all chambers. The lesions may be diffuse or patchy. The ventricular myocardium is typically flabby and often mottled by either pale foci or minute hemorrhagic lesions. The endocardium and valves are unaffected except that mural thrombi may be present in any chamber. Myocardium Microscopic classification: Nonmyocarditis Active myocarditis – Characterized by abundant inflammatory cells and myocardial necrosis Borderline myocarditis – Characterized by an inflammatory response that is too sparse for this type to be labeled as active myocarditis; degeneration of myocytes not demonstrated with light microscopy. Myocardium Histology During Active myocarditis Interstitial mononuclear, predominantly lymphocytic inflammatory infiltrate (focal or patchy) + Focal necrosis necrosis and disarrangement of the myocytes are typical and often are seen with coxsackievirus infection occasionally with a necrotic myocyte (often with contraction bands) Myocardium The histologic pattern of reaction to bacterial or fungal invasion depends on the specific causative organism, if present. Hypersensitivity reactions that involve the myocardium induce interstitial infiltrates that are principally perivascular, composed of lymphocytes, macrophages, and a high proportion of eosinophils. In the chronic and healing stages, myocytes are replaced by fibroblasts (scar tissue). Myocardium – In giant cell myocarditis, giant cells are present in the myocardium with or without granulomas. Tuberculosis, syphilis, rheumatoid arthritis, rheumatic heart disease, or with fungal or parasitic infections. The characteristic cell probably is histiocytic in origin and usually is found in nonviral myocarditis. Similar cells have been noted in patients with myocarditis associated with drugs such as phenylbutazone. Myocardium – Systemic lupus erythematosus (SLE) may demonstrate myocardial fibrinoid lesions found in the connective tissue with an accompanying cellular reaction. This reaction also may affect the valves, most notably, the mitral and aortic valves. Libman and Sacks describe this latter type of endocarditis. Although the predominant cardiac manifestation of SLE is pericarditis, myocardial involvement with CHF can occur Myocardium Viral Myocarditis Myocardium Aspergillus Myocarditis Myocardium Pyemic Myocarditis Myocardium Complications: – Congestive heart failure – Pulmonary edema – Cardiogenic shock – Cardiac failure – Recurrent myositis – Dysrhythmia/Arrhythmia – Thromboembolism. Myocardium Secondary cardiomyopathies Alcohol Chemotherapy (doxo- and daunorubicin; Adriamycin) Cathecolamines and Pheochromocytoma ("catecholamine heart", with single-fiber necrosis as in cocaine heart) Peripartum cardiomyopathy Amyloidosis Hemochromatosis Hyper-/hypo- thyroidism Pompe's glycogenosis Duchenne's & Friedreich's Disease Myocardium End-stage HIV infection Alcohol Alcohol or its metabolites (especially acetaldehyde) has a direct toxic effect on the myocardium Chronic alcoholism may be associated with thiamine deficiency, introducing an element of beriberi heart disease Adriamycin and Other Drugs Some of the chemotherapeutic agents doxorubicin (adriamycin) and daunorubicin are well recognized causes of toxic myocardial injury Many other agents, such as lithium, phenothiazines, and cocaine, have been implicated in myocardial injury Cocaine also causes catecholamine-induced cell damage Myocardium Peripartum cardiomyopathy Pregnancy invokes the possibilities of – hypertension – volume overload – nutritional deficiency – other metabolic derangement – immunologic reaction Myocardium Amyloidosis Cardiac amyloidosis may appear along with systemic amyloidosis or may affect only the heart, particularly in the aged (senile isolated cardiac amyloidosis) Clinically important amyloid deposits can occur in the hearts of patients with multiple myeloma Myocardium Hereditary hemochromatosis and hemosiderosis Most commonly with a dilated pattern Iron deposition is more prominent in ventricles than atria and in the working myocardium than in the conduction system Microscopy – marked accumulation of hemosiderin within cardiac myocytes (intracellular) – Varying degrees of cellular degeneration and fibrosis Myocardium THANK YOU Myocardium