Micro: Myocarditis and Epicarditis Flashcards
Myocarditis
Inflammatory disease of cardiac muscle
Dx on endomyocardial biopsy by established histological, immunological and immunohistochemical criteria
Dx of Myocarditis
Dx on endomyocardial biopsy by established histological, immunological and immunohistochemical criteria
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
Acute Myocarditis
Less distinct onset of illness
Ventricular dysfunction
May progress to dilated cardiomyopathy
Are you more likely to recover from acute of fulminant myocarditis ?
Fulminant
In which patients should you rule in Myocarditis ?
Young person with Unexplained heart failure or arrhythmias with history of:
Systemic febrile illness
URTI
Major causes of mycarditis include
Infection: Viral, bacterial, fungal, parasitic
Autoimmune
Drug Rxns
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
Major viruses associated with myocarditis
Enteroviruses (Coxsackie, Polio etc)
Adenovirus
Parvovirus B19
Human Herpes Virus 6
gold standard of diagnosis for myocarditis
biopsy
pcr becoming more useful however
By what route are Enteroviruses transmitted ?
fecal oral
Which serotype of Coxsackie B is dangerous to neonates leading to febrile illness and sudden unexplained heart failure ?
B3
What mediates entry of Cox. B into myocytes ?
CAR – Coxsackie-adenovirus receptor
What is the mechanism by which coxsackie B causes myocarditis ?
Viral Protease A2 cleaves dystrophin leading to decreased myocyte contractility
Describe the disease caused by Parvovirus B19 ?
Erythema infectiosum (5th disease) aka Slapped cheek fever
How does Parvovirus B19 cause myocarditis ?
Infection of the myocyte endothelial cells leads to decreased endothelial integrity
List the primary bacteria that cause myocarditis
Borelia burgdorferi (causitive agent of lyme disease) Corynebacterium diphtheriae
List the bacterial agents which cause myocarditis by spreading from a previous endocardial infection
Streptococci (Enterococcus) Staphylococci Bartonella Brucella Leptospira Salmonella
Late changes in bacterial myocarditis resemble what other disease ?
dilated cardiomyopathy
How does C.diptheriae cause myocarditis ?
bacterial toxin directly kills myocytes by inhibiting EF-2 via ADP ribosylation
How will you treat a patient with C.diptheriae caused myocarditis ?
Anti-toxin
Describe symptoms/findings of an individual who has diptheria that may be causing myocarditis
Bull Neck (swollen) Grey pseudomembrane on the back of the throat Conjunctivitis
What family of bacteria does Borellia burgdorferi fall into ?
Spirochetes
What percentage of patients with Borellia burgdorferi develop myocarditis ?
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
