Pediatric with right atrium mass and supraventricular tachycardia

Description of Clinical Presentation: Three-year-old female presents with an episode of supraventricular tachycardia with narrow irregular QRS, without hemodynamic compromise, which spontaneously reverted to sinus rhythm. Due to this episode, a transthoracic Doppler echocardiogram was requested. The study revealed the presence of a large, homogeneous mass in the right atrium (RA) obstructing the drainage of the superior vena cava (SVC).



On physical examination, the patient was hemodynamically stable, with no signs of right heart failure.

Diagnostic Techniques and Their Most Important Findings: Doppler echocardiogram:

Homogeneous mass in the RA measuring 2.3 cm x 3 cm, obstructing SVC outflow with a maximum velocity of 1.8 m/s.



Cardiac MRI:

An oval-shaped mass, approximately 5 mm x 4 mm, was observed. It showed the following characteristics across sequences: isointense with myocardium on cine and T2 with fat saturation, mild perfusion during the first pass of gadolinium, and diffuse contrast enhancement.



Surgical excision of the mass was performed.

Histopathological diagnosis: Rhabdomyoma.



In the immediate postoperative period, the patient presented with His bundle rhythm (heart rate 40–60 bpm), requiring a temporary AAI pacemaker. Due to the persistent bradyarrhythmia, a single-chamber permanent pacemaker was implanted.

Learning Points from this Case: Cardiac tumors are extremely rare in children (0.027 to 0.17%). The vast majority of primary cardiac tumors in children are benign, while approximately 10% are malignant. Of these, rhabdomyomas are the most common cardiac tumors, representing 43–60% of cases, and are associated with tuberous sclerosis.



Rhabdomyomas can develop anywhere in the heart, although they are most commonly found in the ventricles and interventricular septal areas, and are often multiple.



The presence of these tumors represents a risk factor for heart failure, arrhythmias, and sudden cardiac death

An oval-shaped mass, approximately 5 mm x 4 mm, was observed. It showed the following characteristics across sequences: isointense with myocardium on cine and T2 with fat saturation, mild perfusion during the first pass of gadolinium, and diffuse contrast enhancement.
Histopathological diagnosis: Rhabdomyoma.