B P6 C55 Myocarditis Flashcards
_____ refers to inflammation of the heart muscle occurring as a result of exposure to either discrete external antigens, such as viruses, bacteria, parasites, toxins, or drugs, or internal triggers, such as autoimmune activation against self-antigens.
Classic myocarditis
Although _____ remains the most commonly identified cause of myocarditis, drug hypersensitivity and toxic drug reactions, other infections, and peripartum cardiomyopathy also can lead to myocarditis.
Viral infection
The pathogenesis of myocarditis is a classic paradigm of cardiac injury followed by _____ response from the host resulting in cardiac inflammation.
Immunologic
Indeed, more than 20 viruses have been associated with myocarditis, and the most frequent are currently _____.
Parvovirus B19 (B19V)
HHV-6
If the host immune response is overwhelming or inappropriate, the inflammation may destroy the heart tissue acutely or may linger, producing cardiac remodeling that leads to _____.
DCM
HF
Death
Disability from myocarditis is largely due to _____.
Heart Failure
The death rate from myocarditis is higher in the _____ year of life than between ages 1 and 14 years for both males and females.
After age 15 years, DALYs, number of deaths, and death rate due to myocarditis are higher in males than females.
1st year of life
After age 15: M>F
Myocarditis is responsible for sudden cardiovascular death in approximately ___% of infants, ___% of children, and ___% of young athletes
2% - Infants
5% - Children
5-14% Young athletes
The standard Dallas criteria define idiopathic myocarditis as an _____.
Inflammatory infiltrate of the myocardium
+
Necrosis and/or degeneration of adjacent myocytes not typical of the ischemic damage associated with coronary artery disease
The presence of viral genomes in heart tissue may indicate an active infectious myocarditis.
In the posttransplantation setting, the presence of viral genomes in myocardial biopsy material predicts future _____ in children
Rejection episodes and graft loss
In most cases, myocarditis is triggered by an inciting event, such as _____ that activates the immune response
Infection
or
Exposure to a drug or toxin
_____ has been implicated as one of the most common infectious causes of myocarditis
Viral infection
Modern virologic and molecular techniques have demonstrated that _____ are among the most commonly identified infectious agents in myocarditis.
Adenoviruses
Parvovirus
Enteroviruses
Endomyocardial Biopsy Diagnosis of Myocarditis: The Dallas Criteria Definition
Idiopathic myocarditis: “an inflammatory infiltrate of the myocardium with necrosis and/or degeneration of adjacent myocytes not typical of the ischemic damage associated with coronary artery disease”
Endomyocardial Biopsy Diagnosis of Myocarditis: The Dallas Criteria Classification
*First biopsy
Myocarditis with or without fibrosis
Borderline myocarditis (repeat biopsy may be indicated)
No myocarditis
*Subsequent biopsy
Ongoing (persistent) myocarditis +/- fibrosis
Resolving (healing) myocarditis +/- fibrosis
Resolved (healed) myocarditis +/- fibrosis
Possible subclinical acute myocarditis criteria
In the clinical context of possible myocardial injury WITHOUT cardiovascular symptoms but with at least one of the following:
Biomarkers of cardiac injury raised
ECG findings suggestive of cardiac injury
Abnormal cardiac function on echocardiogram or CMR
Probable acute myocarditis criteria
In clinical context of possible myocardial injury WITH cardiovascular symptoms and at least one of the following:
Biomarkers of cardiac injury raised
ECG findings suggestive of cardiac injury
Abnormal cardiac function on echocardiogram or CMR
Definite myocarditis criteria
Histologic or immunohistologic evidence of myocarditis
_____ virus infection appears to be mainly associated with cardiomyopathy in Asian countries such as Japan
Hepatitis C
Frequent causes of myocarditis
Adenovirus
Coxsackievirus
Cytomegalovirus
Anthracyclines
Cocaine
Alcohol
As the world has turned its attention to the COVID-19 pandemic, it became clear during the early stages of the disease that patients who were admitted to the hospital for COVID-19 had a ____% incidence of myocardial injury manifested by an increase in troponin and type B natriuretic factor
20-35%
The pathogenesis of cardiac injury in COVID-19 is complex with mechanisms that include _____.
Viral mediated injury
Microvascular dysfunction/ thrombosis
Cytokines
Type II myocardial infarctions
It was assumed initially that this myocardial injury was secondary to a _____ form of myocarditis precipitated by infection of cardiac cells by SARS-CoV-2.
Classical form
The histological features seen at autopsy include _____.
Classic lymphocytic myocarditis is relatively uncommon in COVID-19 patients.
Increased macrophages and cytokine elevation
In retrospective series and autopsy studies in patients infected with HIV, the incidence of cardiac involvement ranged from _____%.
25-75%
Myocarditis with _____ infiltration has been reported in 40% to 52% of patients who die of acquired immunodeficiency syndrome (AIDS)
Lymphocytic infilatration
The incidence of cardiomyopathy, myocarditis, and pericardial diseases correlates with the severity of the HIV infection as measured by a low _____ or high _____.
Low CD4+ count or high viral titers.
In the post–antiretroviral therapy era, _____ are the major cardiovascular diseases that occur in HIV-infected patients in the United States.
ACS and CAD
Nonviral pathogens such as bacteria and parasites can affect the heart and, in some cases, activate an immune reaction in the heart.
Virtually any bacterial agent can cause ______, but it does not necessarily mean that the bacterium has infected the myocardium.
Myocardial dysfunction
In the case of sepsis or other severe bacterial infections, the myocardial dysfunction generally is attributed to ______.
Activation of inflammatory mediators
Of note, however, bloodstream infection by virtually any bacterial infection can result in metastatic foci in the myocardium.
This finding is most commonly associated with _____.
Bacterial endocarditis
Some bacterial infections are well known to have specific effects on the heart that can be mediated by direct infection or activation of inflammatory mechanisms.
The most common of these include _____.
Diphtheria
RHD
Streptococcal infections
Myocardial involvement with _____ is a serious complication and is the most common cause of death in diphtheria.
Corynebacterium diphtheriae
C. diphtheriae produces an _____ that severely damages the myocardium and the cardiac conduction system.
Exotoxin
Cardiac damage is due to the liberation of this exotoxin, which inhibits protein synthesis by interfering with host translational mechanisms.
The toxin appears to have an affinity for the cardiac conduction system. Both antitoxin therapy and antibiotics are important in the treatment of diphtheria.
The most commonly detected cardiac com-plication after _____ infection is acute rheumatic fever, which is followed by rheumatic valve disease in approximately 60% of affected patients.
Beta-hemolytic streptococcal
Rarely, involvement of the heart by the streptococcus may produce a ______ distinct from acute rheumatic carditis.
Nonrheumatic myocarditis
This clinical entity is characterized by the presence of an interstitial infiltrate composed of mononuclear cells with occasional polymorphonuclear leukocytes, which may be focal or diffuse
In contrast with rheumatic heart disease, streptococcal myocarditis usually occurs _____.
Coincident with the acute infection or within a few days of the pharyngitis
Tuberculous involvement of the myocardium occurs by means of ______.
(1) Hematogenous
(2) Lymphatic spread
(3) Arise directly from contiguous structures and may cause nodular, miliary, or diffuse infiltrative disease
In Whipple Disease, electron microscopy has demonstrated rod-shaped structures in the myocardium similar to those found in the small intestine, representing the causative agent of the disease, Tropheryma whipplei, a gram-negative bacillus related to the actinomycetes. An inflammatory infiltrate and foci of fibrosis also may be present. The valvular fibrosis may be severe enough to result in _____. Although it usually is asymptomatic, nonspecific electrocardiographic changes are most common.
AR or MS
Lyme disease is caused by a tick-borne spirochete _____. It usually begins during the summer months with a characteristic rash _____, followed by acute neurologic, joint, or cardiac involvement, usually with few long-term sequelae.
Borrelia burgdorferi
Erythema chronicum migrans
Early studies indicated that up to 10% of untreated patients with Lyme disease demonstrated evidence of transient cardiac involvement, the most common manifestation being _____ of variable degree.
AV block of variable degree
An abnormal _____ scan is compatible with cardiac involvement, and the demonstration of spirochetes in myocardial biopsy specimens of patients with Lyme carditis suggests a direct cardiac effect.
Gallium scan
Patients with Lyme Carditis with second-degree or complete heart block should be hospitalized and undergo continuous electrocardiographic monitoring. _____ may be required for a week or longer in patients with a high-grade block
Temporary transvenous pacing
Intravenous antibiotics are suggested for Lyme carditis, although oral antibiotics can be used when only mild cardiac involvement is present.
_____ may reduce myocardial inflammation and edema, which in turn can shorten the duration of the heart block. It is thought that treatment of the early manifestations of the disease will prevent development of late complications.
Corticosteroids
Chagas disease is one of the major causes of _____ cardiomyopathy throughout the world, although the incidence is changing.
Nonischemic CMP
Symptoms from T. cruzi infection typically begin _____ weeks after a bite from an infected triatomine, or can occur up to a few months after transfusion of infected blood.
1-2 weeks
The parasite load with T. cruzi infection can affect the severity of clinical presentation.
The initial acute phase of the disease begins 1 to 2 weeks after infection and lasts for up to _____ weeks.
4-8 weeks
In the acute phase, the most sensitive diagnostic test is the identification of T. cruzi genetic material in the blood using _____. During the acute phase of parasite infection, most affected patients are either asymptomatic or have mild, subacute febrile illness. Other potential manifestations include adenopathy, hepatomegaly, myocarditis, and meningoencephalitis
PCR assay
