Myocarditis Flashcards
Heart failure in children is most commonly from … ?
Viral myocarditis.
A viral prodrome often precedes the illness, seen with fever, rhinorrhea, congestion, and cervical lymphadenopathy. Patients then typically develop fatigue, tachycardia, and respiratory distress (eg, retractions, nasal flaring, tachypnea, crackles) with hypoxemia from acute left-sided heart failure and pulmonary edema. Because symptoms overlap with common viral illnesses, the diagnosis is challenging and may be delayed. However, progressive symptoms leading to dilated cardiomyopathy with secondary mitral regurgitation can cause an S3 gallop and holosystolic murmur, as seen here. Reduced cardiac output can lead to hypotension, decreased peripheral pulses, and oliguria; hepatomegaly can also occur due to passive congestion from right-sided heart failure. Initial workup includes cardiac enzymes, ECG, chest x-ray, and echocardiogram. Chest x-ray reveals cardiomegaly (cardiothoracic ratio >50% and bilateral hazy opacities (pulmonary edema). Echocardiogram often shows diffuse hypokinesis with decreased ejection fraction. Endomyocardial biopsy or cardiac MRI is needed to confirm the diagnosis, but treatment (eg, diuretics) is often initiated based on clinical suspicion.
What is the most common cause of myocarditis?
Viral infections, particularly Coxsackie B virus, adenovirus, and parvovirus B19.
What is the most common non-infectious cause of myocarditis?
- Idiopathic
- Drug-induced (clozapine, trastuzumab, anthracyclines like doxorubicin)
- Immune-mediated (Giant cell myocarditis, eosinophilic myocarditis)
What are the major infectious causes of myocarditis?
- Viruses (Coxsackie B, adenovirus, influenza, CMV, EBV, parvovirus B19)
- Bacterial (Lyme disease, diphtheria)
- Fungal
- Parasitic (Trypanosoma cruzi in Chagas disease).
What imaging modality is most commonly used for myocarditis?
CXR can be used initially. Cardiac MRI, which shows myocardial edema and late gadolinium enhancement would be used in the confirmatory stages when establishing a diagnosis.
What is the gold standard for diagnosing myocarditis?
Endomyocardial biopsy, though it is not always obtained due to its invasive nature.
What echocardiographic findings are seen in myocarditis?
Global or regional hypokinesis with reduced ejection fraction, often with no coronary artery disease on angiography.
What ECG changes can be seen in myocarditis?
Nonspecific ST-T wave changes, T wave inversions, PR depressions, and possible ventricular arrhythmias.
What inflammatory markers are elevated in myocarditis?
Elevated ESR, CRP, and cardiac biomarkers (troponin, CK-MB).
What is the treatment for viral or idiopathic myocarditis?
Supportive care with heart failure management (ACE inhibitors, beta-blockers, diuretics).
What antibiotic is required for Lyme carditis with myocarditis?
IV ceftriaxone.
What medication is given to reduce anthracycline-induced cardiotoxicity?
Dexrazoxane.
What is the characteristic histological finding in giant cell myocarditis?
Multinucleated giant cells with extensive myocardial necrosis.
What conditions are associated with giant cell myocarditis?
Autoimmune diseases such as thymoma, inflammatory bowel disease, and sarcoidosis.
What is the clinical course of giant cell myocarditis?
Rapidly progressive, often leading to cardiogenic shock and arrhythmias.
