Diverse group of pathologic entities in which microorganisms and/or an inflammatory process cause myocardial injury.
ETIOLOGY • Viral • Non-viral, Trypanosoma, Trichinosis, Toxoplasmosis, Diphtheria. • Non-Infectious due to Hypersensitivity reactions. • Drugs.Antibiotics, Diuretics and anti Hypertensive. Also associated with systemic diseases of immune origin. RF, SLE, polymyositis. Cardiac sarcoidosis and rejection of transplanted heart.
MORPHOLOGYAcute phase heart may be normal or dilated. Some hypertrophy may be present.In advance stages of disease ventricular myocardium is flabby and often mottled with minute hemorrhagic lesions.Mural thrombi in any chamber.During active disease myocarditis is mostly associated with interstitial inflammatory infiltrate associated with focal myocyte necrosis.
Continued Lymphocytic infiltrate is most common and Endomyocardial biopsy is diagnostic.Lymphocytic myocarditis is most common. If the patient survives the acute phase of myocarditis, the inflammatory lesions either resolve, leaving no residual changes, or heal by progressive fibrosis.Hypersensitivity myocarditis has interstitial infiltrate principally perivascular, composed of lymphocytes, macrophages and eosinophils.
Giant-cell myocarditis. characterized by widespread inflammatory cellular infiltrates containing multinucleate giant cells (formed by macrophage fusion) interspersed with lymphocytes, eosinophils, and plasma cells.Myocarditis of chagas disease show parasite trypanosomes accompanied by an inflammatory infiltrate of neutrophils, lymphocytes, macrophages, and occasional eosinophils
CLINICAL FEATURESAsymptomatic, recover completely.Symptomatic, heart failure, arrhythmias and sudden death.Symptoms of fatigue, dyspnea, palpitation, precordial discomfort and fever.c/f mimic acute MI.Occasionaly dilated cardiomyopathy is late complication.
Other causes of myocardial diseaseCytotoxic drugs.Catecholamines, Amyloidosis, Iron over load, Hyper and hypothyroidism.
PERICARDIAL DISEASEDiseases of the pericardium include inflammatory conditions and effusions.Isolated pericardial disease is unusual, and pericardial lesions are almost always associated with disease in other portions of the heart or surrounding structures, or are secondary to a systemic disorder.1)Fluidaccumulation 2)Inflammation 3)Fibrous constriction.Normally fluid 30-50ml thin, clear, strans colomned fluid.
Serous fluid :Pericardial effusionBlood :HemopericardiumPus :Purulent Pericarditis500ml, chronic globular enlargement.In acute state 200-300ml produce compression due to ruptured MI or aortic dissection
PERICARDITISInflammation of pericardium.Primary Rare, viral in origin.Secondary Due to cardiac diseases, thoracic, systemic, metastases, surgical procedures.
ACUTE PERICARDITISSerous Pericarditis: Produced by non- infectious inflammatory disease such as RF, SLE, Scleroderma, tumor, uraemia.Bacterial pleuritis may cause sufficient irritation of pericardium.Viral Infection antedates pericarditis.MORPHOLOGY: Inflammatory reaction with few neutrophils,lymphocytes and histiocytes.
Volume of fluid between 50-200 ml,accumulates slowly.Organization into fibrous rarelr occurs.
FIBRINOUS AND SEROFIBRINOUS PERICARDITISSerous Fluid mixed with fibrinous exudate.Common Causes: Acute MI, Dressler syndrome, Uraemia, Chest radiation, RF, SLE, Trauma.IN FIBRINOUS PERICARDITISThe surface is dry with fine granular roughening.
In sero-fibrinous carditisIntense inflammatory process, produces large amount of yellow to brown fluid with presence of leukocytes and red cells with fibrin.Clinically precardial friction rub heard.Pain, febrile reaction with signs of cardiac failure.
Purulent or suppurative PericarditisInvasion of pericardial space by microbes.a) Direct extension from empyemab) Seeding from bloodc) Lymphatic extensiond) Direct extension during cardiotomyImmunosupression pre-disposes to infection.
ContinuedExudate ranges from thin cloudy fluid to pus 400-500ml, in volume.Serosal surface red, granular and coated with exudate.Microscopically acute inflammatory reaction seen.Scarring produce constrictive pericarditis.Signs of systemic infection noticed.
Haemorrhagic PericarditisBlood mixed with fibrinous or suppurative effusion due to neoplasm. Cytological examination needed.Also seen in bacterial infection due to bleeding diathesis.Also due to cardiac surgery.
Caseous PericarditisRare,due to tuberculosis until proved other wise.It leads to chronic constrictive pericarditis