Micro: Myocarditis and Epicarditis Flashcards by Andrew Gregson

Myocarditis

Inflammatory disease of cardiac muscle

Dx on endomyocardial biopsy by established histological, immunological and immunohistochemical criteria

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Dx of Myocarditis

Dx on endomyocardial biopsy by established histological, immunological and immunohistochemical criteria

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Fulminant myocarditis

Viral prodrome
Distinct onset of illness
Severe cardiovascular compromise with ventricular dysfunction
Multiple foci of active myocarditis
Resolution range from spontaneous clearing to death

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Acute Myocarditis

Less distinct onset of illness
Ventricular dysfunction
May progress to dilated cardiomyopathy

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Are you more likely to recover from acute of fulminant myocarditis ?

Fulminant

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In which patients should you rule in Myocarditis ?

Young person with Unexplained heart failure or arrhythmias with history of:
Systemic febrile illness
URTI

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Major causes of mycarditis include

Infection: Viral, bacterial, fungal, parasitic
Autoimmune
Drug Rxns

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Mechanism of Damage to myocytes

Direct damage to cells

Damage to myocytes from generalized cytokine or cell-mediated immune response

Cytotoxicity caused by viral antigen-specific immune reaction against infected cell

Cytotoxic caused by circulating toxin

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Major viruses associated with myocarditis

Enteroviruses (Coxsackie, Polio etc)
Adenovirus
Parvovirus B19
Human Herpes Virus 6

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gold standard of diagnosis for myocarditis

biopsy

pcr becoming more useful however

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By what route are Enteroviruses transmitted ?

fecal oral

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Which serotype of Coxsackie B is dangerous to neonates leading to febrile illness and sudden unexplained heart failure ?

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What mediates entry of Cox. B into myocytes ?

CAR – Coxsackie-adenovirus receptor

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What is the mechanism by which coxsackie B causes myocarditis ?

Viral Protease A2 cleaves dystrophin leading to decreased myocyte contractility

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Describe the disease caused by Parvovirus B19 ?

Erythema infectiosum (5th disease) aka Slapped cheek fever

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How does Parvovirus B19 cause myocarditis ?

Infection of the myocyte endothelial cells leads to decreased endothelial integrity

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List the primary bacteria that cause myocarditis

Borelia burgdorferi (causitive agent of lyme disease)
Corynebacterium diphtheriae

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List the bacterial agents which cause myocarditis by spreading from a previous endocardial infection

Streptococci (Enterococcus)
Staphylococci
Bartonella
Brucella
Leptospira
Salmonella

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Late changes in bacterial myocarditis resemble what other disease ?

dilated cardiomyopathy

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How does C.diptheriae cause myocarditis ?

bacterial toxin directly kills myocytes by inhibiting EF-2 via ADP ribosylation

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How will you treat a patient with C.diptheriae caused myocarditis ?

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Anti-toxin

Describe symptoms/findings of an individual who has diptheria that may be causing myocarditis

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Bull Neck (swollen)
Grey pseudomembrane on the back of the throat
Conjunctivitis

What family of bacteria does Borellia burgdorferi fall into ?

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Spirochetes

What percentage of patients with Borellia burgdorferi develop myocarditis ?

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10%

What is the most common cardiac manifestation of borrelia infection and what is the prognosis ?

AV nodal block | Spontaneous recovery ! (unlike neurologic findings)

What leads to cardiac damage in myocarditis associated with borellia ?

Damage result of macrophage attacking spirochete

How do you treat borellia associated myocarditis ?

Ceftriaxone or pennicilin temporary pacemaker for individuals with AV block

What is the causative agent of Chagas Disease , which involves myocarditis ?

Trypanosoma cruzi (protozoa, not a bacteria !)

How is T. cruzi transmitted to humans ?

Bite/feces of reduviid kissing bug or triamids

What is a 'Chagonoma' ?

Erythematous and indurated area at site of bug bite

Describe 'Romanas Sign' (associated with Chagas Disease)

Rash and edema around eyes and face Other symptoms of Chagas include: Fever, chills, malaise, myalgia, fatigue

How does T. Cruzi cause myocarditis ?

Parasites multiply in the Myocytes --> cell damage (marked cellular infiltrate) Mechanism for cell damage : Cell Lysis T-Cell mediated

Describe the prognosis for an individual with Chagas associated myocarditis

Usually resolve spontaneously. Some mortality associated with severe cases. In chronic phase of infection parasites enter organs of the body: Liver , Heart, esopahgus and colon leading to inflammation. (Granulomas in the brain)

Describe the chronic phase of Chagas Disease

Can be 20 years later Associated w/poor survival Left ventricular apical aneurysm is typical presentation Megacardia, electrocardiographic changes

The C's of Chagas Disease

Children Chagoma Cardiac Cruzi

How is Chagas Disease diagnosed in the lab ?

Thick and thin blood films – early acute phase Biopsy may show amastigote stage Complement-fixation Xenodiagnosis ( giving uninfected reduviid bugs blood from suspected patients and see if T. cruzi appears) PCR

Pharmacologic treatment of T.cruzi (Chagas Disease)

Nifurtimox Active against acute phase Little activity against amastigotes (dividing stage in tissues)

Pericarditis

Inflammation of the preicardium | Can be infectious or noninfectious

What are the main pathogens associated with Pericarditis ?

Viruses (similar to those that cause myocarditis)

What are the bacteria that typically cause myocarditis

M. tuberculosis Pyogenic Bacteria Pneumococci Staphylococci

How does pericarditis present on examination ?

Pleuritic chest pain High fever Pericardial friction rub ECG abnormalities

What is the most common cause of subacute or chronic purulent pericarditis ?

M.Tuberculosis

List areas in which tuberculosis may have spread to the pericardium from..

Lung/tracheobronchial tree Adjacent lymph nodes Spine, sternum or miliary spread

Is pericarditis due to tuberculosis often due to new infection or reactivation of older infection ?

Reactivation

Dx of tuberculosis

TB in smear or culture of pericardial fluid Histologic examination of caseating granuloma PCR may become useful

Tx of tuberculosis

Isoniazid Rifampin (Rifadin, Rimactane) Ethambutol (Myambutol) Pyrazinamide

Purulent pericarditis

Gross puss in pericardium or microscopic purulence | very rare in this age of antibiotics

Sources of purulent pericarditis causing bacteria ?

Direct spread from intrathoraci foci Hematogenous spread Extension from subdiaphragmatic suppurative focus

Organisms associated with direct intrathoracic spread leading to purulent pericarditis ?

Strep pneumoniae

Organisms associated with hematogenous spread leading to purulent pericarditis ?

Staphylococcus aureus | Streptococci

Organisms associated with extension of myocardial focus spread leading to purulent pericarditis ?

S. aureus Salmonella Those which also cause infective endocarditis

Micro: Myocarditis and Epicarditis Flashcards

(51 cards)