L5 Myocarditis and Pericarditis PDF

(CVS module) Pathology of pericardial diseases and myocarditis By Dr. Marwa Abd El-Fattah 1  Learning Outcomes By the end of the lecture, the student will be able to: List types of pericardial effusion. Recognize causes of p...

(CVS module) Pathology of pericardial diseases and myocarditis By Dr. Marwa Abd El-Fattah 1  Learning Outcomes By the end of the lecture, the student will be able to: List types of pericardial effusion. Recognize causes of pericarditis and pericardial effusion. Outline consequences, fate and clinical effects of percarditis and pericardial effusion. Recognize causes, morphology and effects of myocarditis. Diseases of the pericardium POD-II L25 3  Diseases of the pericardium A.Pericardial effusion B. Acute pericarditis C. Chronic pericarditis  A.Pericardial effusion Types: 1- Hydropericardium: o Accumulation of serous transudate in the pericardial space. o Caused by: - Congestive heart failure - Hypoproteinemia - Chronic liver disease. - Nephrotic syndrome 2- Hemopericardium: o Accumulation of blood in the pericardial space. o Caused by: - Traumatic perforation of the heart or aorta - Pericardial rupture associated with acute myocardial infarction 3- Chylopericardium: o Accumulation of lymph fluid in the pericardial space. o Caused by: - Mediastinal lymphatic obstruction.  Consequences of pericardial effusion It depends on: 1- Volume of fluid. 2- Ability of parietal pericardium to stretch which depends on rate of effusion accumulation.  Thus, slowly accumulating fluid can be tolerated even as large as 1000 mL.  On contrast, rapidly accumulating effusion as little as 250 mL can restrict diastolic cardiac filling or produce cardiac tamponade.  B. Acute pericarditis 1- Serous pericarditis - In most instances, it is caused by viral infection. -The pericardium accumulates a clear, straw colored , protein rich exudate with small number of inflammatory cells. 2-Fibrinous pericarditis “Bread and butter”: -Characterized by fibrin rich exudate. -Typically found in cases of rheumatic fever, SLE. - Found also in cases of uremia, tuberculosis, acute myocardial infarction, collagen vascular disorders. -Clinically it is recognized as a pericardial friction rub. 3-Purulent pericarditis - Characterized by cloudy or frankly purulent inflammatory exudate. - Caused by bacterial pyogenic infection. - Streptococcus pneumoniae, S. aureus, and gram-negative bacilli may invade the pericardial cavity from adjacent infected thoracic organs (e.g., from pneumonia) or during sepsis. 4- Hemorrhagic pericarditis: - Bleeding into the pericardial cavity is usually of a noninfectious nature (e.g., following cardiac surgery or tumor invasion of the pericardium ). - But it may also evolve during severe bacterial infection - Previously, it was a common feature of tuberculous pericarditis. Fibrinous Hemorrhagic POD-II L25 10  Fate of acute pericarditis 1- Resolve without significant sequelae. 2- Rapidly accumulating large effusion can cause cardiac tamponade. 3- Progress to chronic fibrosing process (constrictive pericarditis).  Clinical effects of acute pericarditis 1- Atypical chest pain (not related to exertion and worse in recumbence). 2- Friction rub (Fibrinous pericarditis). 3- Cardiac tamponade and shock.  C-Chronic pericarditis Chronic effusive pericarditis: - Serous fluid persists inside the pericardial cavity. - The amount of fluid varies from 50 mL to 1 L or more. - It is most often idiopathic, but it also may be a residue of an acute infectious pericarditis. Adhesive pericarditis: - Healing of serous pericarditis usually results in no consequences, but it also may result in focal fibrous adhesions. - Such adhesions usually cause no clinical symptoms. Fibrotic or Fibro-calcific pericarditis “Constrictive”: - Extensive scarring that develops from granulation tissue in the pericardial cavity is the end result of severe exudative pericarditis. - Extensive scarring with calcification of the fibrous tissue is an important complication of tuberculous pericarditis.  Constrictive pericarditis - Tuberculous pericarditis is still the leading cause of CP in developing countries and immunocompromised patients - Idiopathic pericarditis remains the predominant cause of CP in the western world, followed by surgery and radiotherapy- induced CP. - There is extensive scarring of the pericardium with proliferation of fibrous tissue and occasional foci of small calcification. -Leading to loss of elasticity that interferes with cardiac dilatation and venous return causing heart failure. Clinical effects of constrictive pericarditis Constrictive pericarditis produces combination of right sided venous distension and low cardiac output.  Tuberculous pericarditis -Common with pulmonary TB. -Route of infection: lymphatic or direct from the pleura. -N/E: Exudate is turbid or blood stained. Areas of caseation. Tubercles may be seen grossly. M/E: Excess lymphocytes & no mesothelial cells  Four stages of TB pericarditis 1) Dry stage: in which patients present with an acute pericarditis syndrome progresses to……> 2) Effusive stage: (the most common at presentation) characterized by a sero-sanginous pericardial effusion. The effusion then organizes into……> 3) Absorptive stage: during which caseaus granulation and fibrin deposition occurs to form a thickened pericardium. This is the precursor to the final…..> 4) Constrictive stage: during which the visceral and parietal pericardium become fibrosed and calcified, leading to the clinical syndrome of constrictive pericarditis. Tuberculous pericarditis POD-II L25 18 POD-II L25 19  Myocarditis Definition: A group of clinical entities in which the infectious agent and/or the inflammatory process primary target the myocardium.  Morphology M/E: Edema Inflammatory infiltrate Myocyte injury. POD-II L25 21  Causes of myocarditis 1- Infective myocarditis: A- Viral: Viral infections are the most common cause of myocarditis. Parvovirus B19, Coxsackie B virus, human herpes virus 6 (HHV6), adenovirus. Cytomegalo virus, HIV and influenza viruses are less common agents. B- Bacterial: pyemia and septicemia. C- Protozoal: Trypanozuma cruzi : causing Chagas disease. Toxoplasma gondii: in immunocompromised patients. Trichinosis: the commonest helmenthic infection causing myocarditis. Lyme disease: caused by Borrelia burgdorferi. 2- Non infective myocarditis: A-Toxins: Anthracyclines, Cocaine, Catecholamines B- Immunological syndromes: IBDs, Sarcoidosis, SLE C- Hypersensitivity reaction to drugs: Penicillin, Cephalosporins, Tetracyclines, Diuretics, Tricyclic antidepressants, others.  Common causes of myocarditis Viral infection is the most common etiology, but several other etiologies of myocarditis have also been implicated. Pollack, A. et al. (2015) Viral myocarditis—diagnosis, treatment options, and current controversies Nat. Rev. Cardiol. doi:10.1038/nrcardio.2015.108  Clinical effects of myocarditis 1- May be asymptomatic. 2- May mimic clinical features of myocardial infarction. 3- Fatigue, dyspnea, palpitation, pain and fever. 4- Heart failure or arrhythmias.  RECOMMENDED REFERENCES 1. Robbins & Cotran Pathologic Basis of Disease, (Robbins Pathology), 2018 ISBN: 978-0-323-35317-5, Edition: 10th 2. Pathmax: http://www.pathmax.com/ 3. Webpath: http://library.med.utah.edu/webpath/webpath.html