Pericardial Diseases Associated with diseases in heart and surroundingstructures, or secondary to systemic disorders. Isolated pericardial disease is unusual.Pericardial effusion and haemopericardium: Normally, there is 30 to 50 mL of thin, clear,straw-colored fluid in pericardial sac. Parietal pericardium undergoes distention by fluidof variable composition (pericardial effusion).
The consequences depend on: ability of parietalpericardium to stretch, speed of accumulation,and amount of fluid. Thus, with slowly accumulating effusions, the onlyclinical significance is globular enlargement ofheart shadow on chest x-ray. In contrast, rapidly developing fluid collectionsin haemopericardium caused by ruptured MI ,ortraumatic perforation may produce fatal cardiactamponade.
Acute Pericarditis:Serous Pericarditis: produced by:o Non infectious inflammations: RF, SLE, scleroderma,tumors, and uremia.o Viral infection elsewhere: upper respiratory tractinfection, pneumonia, parotitis.o Viral pericarditis that accompany viral myocarditis(myopericarditis).
Morphology: An inflammatory reaction with scant numbersof polymorphnuclear leukocytes, lymphocytes,and macrophages. The volume of fluid is not large (50 to 200 mL)and accumulates slowly. The fluid has low specific gravity, and low proteincontent.serous fluid, at the bottom of pericardial cavity (arrow).
Fibrinous and Serofibrinous Pericarditis: Composed of serous fluid mixed with fibrinousexudate. Common causes: acute MI , postinfarction (Dressler)syndrome , uremia, chest radiation, RF, SLE, andtrauma. A loud pericardial friction rub is characteristic offibrinous pericarditis. Pain , systemic febrile reactions, and signs ofcardiac failure may be present.
Morphology: The surface is dry with a fine granular roughening. An increased inflammatory process induces moreand thicker fluid which is yellow and cloudy owingto leukocytes and erythrocytes and often fibrin. Fibrin may be digested with resolution of exudate,or it may become organized.
Purulent or Suppurative Pericarditis: Invasion of pericardial space by infective organismswhich may reach pericardial cavity by :(1) direct extension from neighboring inflammation:-an empyema of pleural cavity, lobar pneumonia,or mediastinal infections.(2) seeding from blood.(3) lymphatic extension.(4) direct introduction during cardiotomy.
Morphology: The exudate ranges from a thin to a creamy pus . The serosal surfaces are reddened, granular, andcoated with exudate . Microscopically:o There is an acute inflammatory reaction.o Organization is the usual outcome.o Resolution is infrequent.
Hemorrhagic Pericarditis: An exudate composed of blood admixed withfibrinous or suppurative effusion. Commonly caused by malignant neoplasticinvolvement of pericardial space. May also be found in bacterial infections,in patients with an underlying bleeding diathesis,and in tuberculosis. Often follows cardiac surgery and sometimesis responsible for significant blood loss or evencardiac tamponade.
Caseous Pericarditis: Caseation within pericardial sac, until provedotherwise, is tuberculous in origin. Infrequently, fungal infections evoke a similarreaction. Pericardial involvement occurs by direct spread fromtuberculous foci within tracheobronchial nodes. It is rare but is the most frequent cause offibrocalcific chronic constrictive pericarditis.
Chronic or Healed Pericarditis: In some cases, organization produces plaque-likefibrous thickening of serosal membranes. This fibrosis yields adhesion between parietal andvisceral pericardium called adhesive pericarditis. In other cases, organization results in completeobliteration of pericardial sac.
Constrictive Pericarditis: The heart encased in a dense fibrous or fibrocalcificscar that limits diastolic expansion and seriouslyrestricts cardiac output. History of previous pericarditis may or may not bepresent. The pericardial space is obliterated. The major therapy is surgical removal of the shellof constricting fibrous tissue (pericardiectomy).
This photograph showed pericardial fibrosis and calcification (Hematoxylin andeosin stainx40).
Tumors of the Heart Primary tumors of heart are rare. In contrast, metastatic tumors to heart occur inabout 5% of patients dying of cancer. The most common primary tumors , in descendingorder of frequency are: myxomas, fibromas,lipomas, papillary fibroelastomas, rhabdomyomas,angiosarcomas, and other sarcomas. The first five tumors are all benign and accountfor 80% to 90% of primary tumors of the heart.
PRIMARY CARDIAC TUMORS :Myxoma: Most common primary tumor of heart in adults. 90% are located in atria, with left-to-right ratioof 4:1. The major clinical manifestations are due tovalvular "ball-valve" obstruction and emboli. Echocardiography to identify these massesnoninvasively. Surgical removal is usually curative. Rarely , the neoplasm recurs months or years later.
10% of patients have familial cardiac myxomasyndrome (known as Carney syndrome).Morphology: Almost always single. Fossa ovalis in atrial septum is favored site . Range from small ( 1 cm) to large (up to 10 cm). Sessile or pedunculated masses. Vary from globular hard masses mottled withhemorrhage, to soft papillary or villous lesionshaving a gelatinous appearance.
The left atrium has been opened to reveal the most commonprimary cardiac neoplasm - atrial myxoma.
Histologically : Composed of stellate or globular myxoma ("lepidic")cells , smooth muscle cells, and undifferentiated cells. Embedded within abundant acid mucopolysaccharideground substance. Covered on the surface by endothelium. Hemorrhage and mononuclear inflammation areusually present.
Lipoma: May occur in subendocardium , in subepicardium,or within myocardium. Localized poorly encapsulated masses. May be asymptomatic, can create ball-valveobstruction as myxomas, or may producearrhythmias. Most often located in left ventricle, right atrium,or atrial septum.
Papillary Fibroelastoma: Most often identified at autopsy. They may embolize and become clinically important.Morphology: Generally located on valves. They constitute a distinctive cluster of hair-likeprojections up to 1 cm in diameter ( sea anemoneappearance).
On light microscopy: fronds of connective tissue are eosinophilic (pink) and show minimalcellularity. The most conspicuous cells are endothelial cells on the surface of "papillary"fronds. (right) shows yellow collagen with concentric discontinous layers of elastic lamellaein the core. Thus the name fibroelastoma
Rhabdomyoma: Most frequent primary tumor of heart in infants andchildren. Frequently discovered in first year of life becauseof obstruction of valvular orifice or cardiac chamber. High frequency of tuberous sclerosis in patientswith cardiac rhabdomyomas. A recent study suggested that cardiac rhabdomyomasmay be due to a defect in apoptosis duringdevelopmental cardiac remodeling.
Morphology: Small gray-white myocardial masses up to severalcentimeters in diameter located on either left orright side of heart and protruding into ventricularchambers. Histologically:Composed of large rounded or polygonal cellscontaining numerous glycogen-laden vacuoles whichseparated by strands of cytoplasm running fromplasma membrane to more or less centrally locatednucleus, the so-called spider cells.
Gross appearance of cardiac rhabdomyoma.Multiple rhabdomyomas (arrows) in a childwith Tuberous Sclerosis (at autopsy).
Metastatic tumors to the heart: The most frequent primaries are:carcinomas of lung and breast, melanomas,leukemias, and lymphomas. Metastases can reach heart and pericardium by:o Lymphatic extension (most carcinomas).o Hematogenous seeding (many tumors).o Direct contiguous extension (primary carcinoma oflung, breast, or esophagus).
Clinical symptoms: either byo Pericardial spread with pericardial effusion thatcauses tamponade.o Tumor bulk that is sufficient to directly restrictcardiac filling. Bronchogenic carcinoma or malignant lymphomamay infiltrate mediastinum causing compression,or invasion of superior vena cava with resultantobstruction to blood coming from head andupper extremities (superior vena cava syndrome).
Renal cell carcinoma can grow in lumen of renal vein,and into inferior vena cava and blocking venousreturn to heart. Noncardiac tumors cause indirect cardiac effectsvia circulating tumor-derived substances ( NBTE ,and carcinoid heart disease). Complications of tumor radiotherapy:o Radiation can cause pericarditis, pericardial effusion,and myocardial fibrosis.