P0410 - Supraventricular Tachyarrhythmia as a Harbinger of an Intracardiac Mass

Introduction:
Arrhythmias are a rare presenting symptom of atrial masses. Primary cardiac masses occur in less than 0.1% of the population.

Case Description:
A 13 year old male from Ethiopia was admitted with a hydropneumothorax. He had three self-resolving runs of supraventricular tachycardia (SVT). Telemetry did not show any other ectopy. A transthoracic echocardiogram (TTE) showed a large, mobile right atrial mass attached to the atrial septum by a narrow stalk (Figure 1). Given the risk of embolization and arrhythmias, the patient was transferred to the ICU and underwent urgent excision of the mass. An intraoperative transesophageal echocardiogram (TEE) delineated a single mass with additional attachments to the atrial wall. Pathology was consistent with a thrombus. The patient was subsequently found to have a pulmonary embolism and embolic renal infarcts. He was started on anticoagulation, although his hypercoagulable workup has been unrevealing.

Discussion:
Given that our patient had new-onset arrhythmias while hospitalized for a hydropneumothorax of unknown etiology, the level of suspicion was higher than a typical pediatric patient with SVT. A TTE was done to rule out an anatomic cause. New-onset SVT is given an “A” (Appropriate) rating by the 2014 Appropriate Use Criteria for Initial TTE in Outpatient Pediatric Cardiology. However, there is not a consensus for initiating the workup of a new atrial arrhythmia in the inpatient setting.

Conclusion:
Intracardiac masses are a rare cause of arrhythmias in pediatric patients. Including a TTE in the workup is an important diagnostic step and should be considered in the inpatient setting.