SAN DIEGO– Pediatricians are at risk of misdiagnosing myocarditis despite its severity. That’s because children tend to present with abdominal symptoms and a history of a recent viral illness that lacked signs of cardiac involvement, Dr. Kevin Shannon said.
“Typically, they have a bout of flu, they seem to be getting better, and then they start vomiting or having stomach pain again,” he said at the annual meeting of the American Academy of Pediatrics.
Viruses ranging from adenovirus to varicella have been implicated in myocarditis in children (J. Clin. Microbiol. 2010;48:642-5; Pediatr. Cardiol. 2011;32:1241-3). Pediatricians should watch for patients who were recently ill and are now presenting with an apparent relapse and tachycardia that is worse than how they appear overall, said Dr. Shannon, a pediatric cardiologist at the University of California, Los Angeles, Medical Center. “A lot of these children will seem more ill than their vomiting will suggest,” he added. “They’ll have a heart rate of 180 [beats per minute] that is out proportion to how they look.”
Fluid therapy does not improve tachycardia and may even worsen it, indicating that dehydration is not the underlying cause, said Dr. Shannon. Children with viral myocarditis also often have acute upper-right quadrant pain as a result of hepatic distension, he said.
Laboratory findings can be very helpful. Cardiac troponin T is almost always elevated in children with myocarditis (Pediatr. Emerg. Care 2012;28:1173-8), and erythrocyte sedimentation rate also may be high. Electrocardiography can show a variety of focal or diffuse abnormalities, none of which are pathognomonic for the condition, Dr. Shannon said. Focal abnormalities can mimic an ST segment elevation myocardial infarction (STEMI), he added.
On chest x-ray, the heart margins also are often normal because the heart has not yet enlarged to compensate for impaired function, said Dr. Shannon. “This is a poorly functioning, normal-sized heart,” he added. Chest films often will reveal interstitial edema that might be misinterpreted as interstitial pneumonia, in keeping with the child’s recent illness.
Treatment of acquired myocarditis is based on supportive care, said Dr. Shannon, adding that use of immunomodulators in children with myocarditis is controversial. “If they have low blood pressure, they need volume, even if their heart rate gets higher,” he added. “If they don’t tolerate fluid therapy, they need inotropes and sometimes intubation.”
Dr. Shannon reported no conflicts of interest.