While a child who died displayed many signs of myocarditis, inflammation of the heart, the condition is "very rare" and hard to diagnose, experts have told a coronial inquest.
Five-year-old Rozalia Spadafora is believed to have died from influenza-A induced myocarditis at Canberra Hospital on July 5, 2022.
Three experts answered questions on various aspects of her care on the eighth day of the coronial inquest.
Myocarditis is inflammation of muscle of the heart and can be caused by a virus or a post-infection immune response, paediatric infectious disease specialist Associate Professor Mike Starr told the court on Wednesday.
"Many clinicians will go through their careers without seeing [it]," Dr Starr said.
He said the symptoms are also common in other conditions, particularly viral illnesses.
Paediatric intensive care specialist Dr Marino Festa said an aggressive and life-threatening version of the condition is even more rare.
He said symptoms include abnormal heart rhythm, a rapid deterioration of the heart over hours. It is known that influenza is a cause of this severe version of myocarditis.
Emergency doctor Dr Robert Day said myocarditis can occur in otherwise healthy children, .
A child with myocarditis may look pale, sick, and have a rapid heart rate and low blood pressure, Dr Day said
Heart failure can be harder to pick in children than adults because adults are more compliant with clinical examination, Dr Festa said.
He said one sign is an enlarged liver, which can be caused by the right side of the heart failing. This was seen in Rozalia. However, it is not only a sign of heart failure.
While the "gold standard" of diagnosing myocarditis caused by influenza is a biopsy, Dr Starr said he believed this condition is what killed Rozalia.
Doctors should be careful in diagnosing myocarditis and make sure to eliminate other possible conditions, Dr Festa said.
A key issue in this coronial inquest is the amount of fluid Rozalia was given, which may have overloaded her heart.
Dr Festa said an adage in intensive care is "you never flog an empty ventricular".
Myocarditis makes it harder for the heart to pump fluid.
However, Dr Starr said children often needed fluid when first presenting to a hospital because "if they're sick they are often dehydrated".
Dr Festa agreed that myocarditis in children would more commonly be seen in tertiary care hospitals, which will have more serious cases, but referring hospitals such as Canberra Hospital still needed to be aware of the condition.
"Individual hospitals will get sporadic cases," he said.
He said knowledge gained in the big hospitals should flow down to "make sure these children are identified and properly managed".
The inquest continues on Wednesday afternoon.