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Download Tutorial 4 - University of Prince Edward Island
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Pathology of the Pericardium Alfonso López Professor of Anatomic Pathology Dept. Pathology and Microbiology Atlantic Veterinary College University of Prince Edward Island Canada Janvier 23, 2013 Pericardium and Epicardium The pericardium is a double layered serosal membrane that covers the heart and the most proximal segment of the great vessels. Note the pericardium forming a complete sac around the heart and major vessels (blue arrows) The epicardium is the thin layer of pericardium firmly attached to the heart (star). Pericardium and Epicardium • The most external and thicker layer of the sac is the pericardium while the most internal and thinner layer is intimately attached to the myocardium and is called the visceral pericardium, also called epicardium. * • These two serosal membranes are composed of a thin layer of mesothelium and connective tissue which supports blood vessels, lymphatic vessels, nerves and adipose tissue. • The normal epicardial fat (asterisk) generally follows the coronary grooves. The pericardial sac (pericardium) was removed to expose the epicardium Normal histology Epicardium Coronary Artery Myocardium Pericardium and Epicardium Epicardium Pericardium The pericardial sac contains small traces of fluid which acts as a lubricant to prevent friction between the pericardium and epicardium. Dissention of the Pericardial Sac The pericardial sac can notably enlarge on physical demand to accommodate: • Excess fluid in hydropericardium • Non-fatal progressive pericardial hemorrhage in hemopricardium • Exudate in pericarditis • Enlarged heart in cardiac hypertrophy and cardiomyopathy. Post-mortem Examination of the Pericardium Before opening the pericardial sac, you must carefully evaluate: • Relative size of the cardiac silhouette. • Presence of pericardial effusion or exudate. If present, take a sample using a needle and syringe for bacteriology or cytology. • Amounts of fat in pericardium and epicardium as indicator of body condition. Normal pericardial fat in a cow Emaciated animals typically shows serous atrophy of fat in the pericardium, perireneal fat and bone marrow (next 2 slides). Epicardial fat appears gelatinous Serous Atrophy of Fat Serous atrophy of fat Normal Fat Also note prominent normal lymphatic vessels (arrows) Serous atrophy in bone‐marrow. Note gelatinous appearance Emaciated cow Serous atrophy of fat in pericardium and kidney Normal renal fat Pericardial Hemorrhages Pericardial hemorrhages are common post-mortem findings in animals that have suffered prolonged agony, hypoxia, sepsis and septicemia, toxemia, DIC, coagulopathies and electrocution. According to size, hemorrhages are classified as: Petechial Ecchymotic Paint brush Pericardial Effusions Transudate Hydropericardium Clear fluid, low cellularity, low protein Blood Hemopericardium Predominantly RBCs, high protein Exudate Pericarditis Turbid, high cellularity, PMNs, high protein Hydropericardium • Low protein transudate in the pericardial sac • Pericardial surfaces remain smooth and glistening • According the pathogenesis: • Hydrostatic: i.e., Right heart failure, pulmonary hypertension • Hypoproteinemia: emaciation, protein losing enteropathy / nephropathy, etc. • Altered vascular permeability: i.e., mulberry heart Hydropericardium / Dog Hydropericardium: Note the two hearts floating in distended pericardial sacs filled with abundant clear transudate (arrows). Chicken / Salt (NaCl) Toxicity Duck Courtesy: Dr. Carlos Lopez Mendez Hemopericardium • Accumulation of blood in the pericardial sac • Caused by atrial or aneurismal rupture, hemangiosarcoma, cardiac puncture. • Acute hemorrhage can cause cardiac tamponade sudden death • Caution: blood tinged fluid occurs as a post-mortem finding Hemopericardium Note the pericardial sac notably distended with blood (syringe) Hemopericardium Note the pericardial sac notably distended with blood. The rib imprints are visible in the distended pericardium (arrows) Hemopericardium Warfarin Toxicity /Cornell Note the pericardial sac filled with unclotted blood Sudden death Post‐mortem revealed an enlarged cardiac silhouette and a notably distended pericardial sac filled with blood. A good example of hemopericardium. Heart lesions responsible for intrapericardial bleeding and sudden death in this dog are shown in next slide. Hemangiosarcoma, dog. Tumoral mass in the right atrium (arrows). This tumor is dark because neoplastic cells form blood‐filled vascular channels. More information about hemangiosarcoma is available in the last tutorial module. Fixed specimen Pericarditis Note enlarged cardiac silhouette. Also, rib imprints can be seen in the pericardial sac (arrows). According to exudate: • Fibrinous (most common) • Suppurative (purulent) • Fibrinohemorrhagic • Granulomatous Fibrinous Pericarditis Note thick layer of yellow fibrin, purulent fluid at the bottom and thick fibrous pericardium (stars). Traumatic Reticulopericarditis Pericardial sac filled with exudate Relationship between reticulum and pericardium (arrow) Wire and nails Traumatic reticulopericarditis • Enlarged cardiac silhouette (yellow dots) • Pericardial sac filled with organized fibrin (star) showing bread and butter appearance ② ① Lung Constrictive Pericarditis 1. Brisket edema due to right heart failure (compressive) 2. Distended pericardial sac 3. Pericardial sac filled with fibrin and blood and organized fibrosis on the epicardium ③ Fibrinous pericarditis “bread and butter” Epicardiium Pericardial sac Note organized fibrin covering the epicardium and pericardium. This morphologic appearance is often referred to as bread and butter. If you put butter between two slices of bread and then quickly open the sandwich, the butter would take this appearance. Chronic Constrictive Pericarditis Fibrin Fibrosis Myocardium H&E stain Note thick fibrous pericardial sac (stars). So much fibrosis causes constrictive pericarditis which result in impaired diastole and abnormal ventricular filling. Masson‐Trichrome stain Do you know the difference between fibrinous and fibrous? Two terms often confusing for students Fibrinous pneumonia Fibrous adhesions between visceral and parietal pleura (arrows) Fibrin or fibrinous is a type of exudate that originates when fibrinogen, a normal blood protein involved in coagulation, leaks into tissues during inflammation. Once in the tissues, plasma fibrinogen coagulates forming fibrin, a fibrillar exudate with a characteristic yellow color. Fibrinous inflammation occurs in most organs hence the terms fibrinous pneumonia, fibrinous pericarditis, fibrinous arthritis, fibrinous peritonitis, etc. Fibrous or fibrosis is proliferation of connective tissue in chronic inflammation. It is composed by fibroblasts and collagen fibers and cells seen in chronic inflammation such as macrophages, lymphocytes and plasma cells. Proliferation of fibrous connective tissue often forms fibrous adhesions between organs such as lung and pleura or between epi- and pericardium. Chronic Pericarditis with fibrous adhesions in a pig Fibrous adhesions covering the epicardial surface. This pig first had fibrinous pericarditis which turned with chronicity into pericardial fibrosis. Note fibrous band on the epicardium (arrows). Restrictive pericarditis caused ventricular hypertrophy (star) ① ② Polyserositis (Glasser’s Disease) Haemophilus parasuis 1. Affected pig 2. Fibrins strands in pericardial sac 3. Firbinopurulent exudate in joint Streptococcus suis type 2 can also cause similar lesions in pigs ③ ① ② Black Leg / Clostridial Myositis Fibrinous pericarditis is commonly seen in Black Leg (Clostridium chauvoei) 1. Cow submitted for post-mortem 2. Black discoloration of the leg muscle 3. Fibrins strands in the pericardial sac ③ What about me? Compared to other domestic species, dog and cats rarely develop fibrinous pericarditis Thank to all AVC pathologists for contributing case materials. Some images were acquired from veterinary colleges of Canada, United States and Mexico and the names of some contributing pathologists are unknown. Their valuable contribution is sincerely acknowledged. I would like to thank Dr. Shannon Martinson, Atlantic Veterinary College, for critically reviewing these modules. Module 4: Pathology of the Pericardium THE END If you have any comments or criticisms about tutorials or quizzes please let me know. Also, if you find any errors or typos please let me know. [email protected]
