A Large Cardiac Mass in an Infant

A 12-month old, 11 kg, previously healthy, asymptomatic female was seen in the cardiology clinic for a persistent heart murmur. On physical exam, she had a Grade III/VI unusually low-pitched continuous murmur heard best along the lower left sternal board without radiation.

An echocardiogram demonstrated a large circular echo bright intracardiac mass measuring 14mm x 15mm that appeared to attach to the endocardium by a broad base along the right ventricular side of the interventricular septum, just below the tricuspid septal leaflet (Videos 1 and 2), with the potential for tricuspid inflow obstruction. The bi-ventricular size and systolic function were normal. There was trivial tricuspid regurgitation, with no right ventricular outflow obstruction. No other structural cardiac abnormalities were seen.

Cardiac MRI (cMRI) was performed which also demonstrated a large right ventricular mass on the septal side of the basal right ventricular chamber, in close proximity to the tricuspid valve apparatus (Video 3). Holter monitoring showed normal sinus rhythm throughout.

Video 1

Two-dimensional and color Doppler of the tricuspid valve in an apical four-chamber view. A large, circular echobright structure appears adherent to the septal leaflet of the tricuspid valve. There is mild tricuspid regurgitation, but now inflow obstruction.

Video 2

Two-dimensinoal view of the tricuspid valve in a parasternal long axis view. A large, circular echobright structure measuring 18 x 18 mm is seen. It appears adherent to the septal leaflet of the tricuspid valve and moves in concert with the valve apparatus.

Video 3

Cardiac MRI. After administration of contrast, a T1-weighted black blood image in the short axis reveals a peripherally enhancing mass at the basal portion of the right ventricle, measuring approximately 18 x 18 mm.

Which of the following is the most appropriate next step in the management of this patient?

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