Cv System Exam 2_1: Myocarditis And Chagas Dz

Front 1

define myocarditis

Back 1

inflammation of the myocardium; infectious microorgs, toxins or autoimmune inflammatory processes cause myocardial injury

Front 2

adult incidence of myocarditis

Back 2

10/100,000 - 5/100

Front 3

neonatal incidence

Back 3

60-70% acquired from mother; 30-40% acquired from hospital staff (nosocomial); Mortality rate is 50-75% with death within 1 week

Front 4

myocarditis etiological agents

Back 4

-adenovirus
-coxsackie virus (enterovirus)
-trypanosoma cruzi

Front 5

most common cause of myocarditis in kids

Back 5

adenovirus

Front 6

most common cause of myocarditis in adults

Back 6

coxsackie virus

Front 7

cinical presentation of myocarditis

Back 7

protean Sx: fatigue, dyspnea; Diffuse mononuclear inflammatory infiltrate is most common; acute, subacute or chronic; Survival: inflammatory lesions resolve or heal by progressive fibrosis

Front 8

Viral myocarditis - Pathophys Phase 1: Viral

Back 8

Adenovirus and coxsackievirus enter via the GI or respiratory system by binding the coxsackie-adenoviral receptor (CAR), a junctional protein that is highly expressed in the heart, brain and gut

Front 9

Viral myocarditis - Pathophys Phase 2: Immune Response

Back 9

Virus or the immune response (innate immune response and CTLs) cause acute injury leading to cardiac damage

Front 10

Viral myocarditis - Pathophys Phase 3: Cardiac Remodeling

Back 10

virus-mediated cardiac injury and the immune response may destroy heart tissue acutely or linger and produce cardiac remodeling leading to cardiomyopathies, heart failure or death

Front 11

myocarditis most likely outcome for otherwise healthy patients

Back 11

typically resolves without complication

Front 12

myocarditis diagnostics

Back 12

PCR and in situ hybridization (molecular tools to detect viral nucleic acid); newer imaging techniques such as PET-CT (detects inflammation of the myocardium). Cardiac magnetic resonance imaging (CMR) allows visualization of the entire myocardium (pre/post contrast)

Front 13

myocarditis therapeutics

Back 13

Type I interferons exert anti-viral activity; immunoglobulins (IVIG to block the autoimmune component) and antiviral agents. Immunosuppressants - unclear if useful; the immune response is as much protective as it is harmful

Front 14

Why are the unrelated coxsackie and adenoviruses both major causes of myocarditis?

Back 14

both enter via the GI or respiratory system by binding the *coxsackie-adenoviral receptor (CAR)*, a junctional protein that is highly expressed in the heart, brain and gut

Front 15

What type of patients have poor prognosis with myocarditis?

Back 15

Less common viral causes occur mostly in immunocompromised patients: CMV, HIV (HIV-associated myocarditis = poor prognosis)

Front 16

picornaviruses

Back 16

literally means small RNA virus;
Non-enveloped RNA viruses with an icosahedral capsid- enteroviruses, Hep A and Rhinoviruses.

Front 17

Myocarditis - Non-viral causes

Back 17

Virtually any bacterial agent can cause myocardial damage due to release of inflammatory mediators (activation of Toll-like receptors and production of inflammatory cytokines such as TNF-a)

Front 18

Toxic myocarditis

Back 18

may occur in diptheria

Front 19

Myocarditis occurs in 5% of ______ disease patients (Borrelia burgdorferi)

Back 19

Lyme Dz

Front 20

diptheria

Back 20

is an acute infectious disease caused by the bacteria Corynebacterium diphtheriae

Front 21

myocarditis morphological features

Back 21

-Lymphocytic myocarditis
-Hypersensitivity myocarditis
-Giant-cell myocarditis
-The myocarditis of Chagas disease

Front 22

In situ hydridization

Back 22

detects presence of viral
DNA (blue stain)

Front 23

viral myocarditis antigenic mimicry

Back 23

T cells and antibodies can react with viral proteins that mimic those of the host (ex. cardiac myosin) - this is termed molecular or antigenic mimicry and it can trigger autoimmunity [don't forget APC involvement; look at slides 26-28]

Front 24

A 6-day old baby is brought to the emergency department with a 2-day history of tachypnea, tachycardia and diaphoresis. The baby has a fever, is anorexic and is in acute respiratory distress. The baby’s mother has a runny nose, headache and sore throat. The most likely etiology of the baby’s symptoms is:

Back 24

adenovirus infection

Front 25

Myocarditis - Diagnosis

Back 25

auscultation: rarely audilbe
ECG: rule out
Blood: increase in creatine kinase or appearance of troponin may indicate myocyte necrosis (myocytolysis); autoantibodies may appear only later in the disease process
Heart biopsy: detect presence of inflammatory cells simultaneous with evidence of myocyte degeneration or necrosis on same section of the biopsy specimen. Serology is of limited value

Front 26

Myocarditis - Treatment

Back 26

supportive care, bed rest, cardiac monitoring, anti-arrhythmic agents, fluid management, drugs to treat heart failure

Front 27

A 20-year old man with no previous cardiac history presents with severe acute chest pain, fatigue, dyspnea and palpitations. He appears healthy, denies narcotic use and has not traveled outside of the US in the past year. The most likely etiology is:

Back 27

Most of these can cause myocarditis but the most common cause, especially as the patient has not traveled outside the US, is Coxsackievirus.

Front 28

In the previous case a cardiac biopsy is performed and analyzed by the polymerase chain reaction (PCR) to detect:

Back 28

Viral nucleic acid-PCR detects nucleic acid by amplifying specific genomes of a given virus. Viral antibodies may be present but this does not definitively indicate a viral cause of myocarditis. In addition, antibodies may arise a few weeks following the onset of symptoms and thus may not be detected when serology is performed.

Front 29

In the previous case, if the patient’s blood showed elevated anti-viral antibodies, the mechanism involved in the patient’s disease would most likely be due to virus activation of:

Back 29

Toll-like receptors- Viruses, like all microbes, bear pathogen-associated molecular patterns, such as viral nucleic acid, that activate toll-like receptors resulting in the activation of innate immune responses.

Front 30

Chagas Dz

Back 30

[American trypanosomiasis]
Infectious agent : Trypanosoma cruzi (flagellated protozoan)

Front 31

Diseases of Trypanosomes

Back 31

Chagas disease – American trypanosomiasis (kissing bug vector)
African sleeping sickness – African trypanosomiasis (tsetse fly vector)

Front 32

Triatomid insect = reduviid = “Kissing bug”

Back 32

Bloodsucker, likes faces… bites and then poops out a parasite which you scratch and cause bodily entrance. Parasite likes heart and nerves. Morphology of parasite changes to round form and multiply within cells, change to flagelated form and spread to other areas.

Front 33

Chagas Acute Phase

Back 33

-1-2 weeks
-Usually mild; weeks to month -Fever, fatigue, rash
-Swelling at infection site; Chagoma
-Rarely, myocarditis

Front 34

Chagas chronic phase

Back 34

-10-30 years
-Palpitations, dyspnea, syncope due to enlarged heart, altered heart rate or rhythm (may be fatal)
-Dysphagia or constipation → due to mega-esophagus, mega-colon

Front 35

Key factors for Dx of Chagas

Back 35

Romanas sign (one swollen-shut eye) and recent trip to South America