Caval vein obstruction resulting in right to left shunt and desaturation post-endocardial pacing implantation in a 3-year old: a case report.

Background: Superior caval vein obstruction is a rare complication of endocardial pacing lead implantation that can result in a right to left shunt. Case summary: A 3-year-old child with type 2 Brugada syndrome presented with mild cyanosis post-endocardial pacing implantation due to evolutionary right superior caval vein obstruction. This obstruction resulted in a right to left shunt across a previously unrecognized patent levo-atrial cardinal vein associated with partial anomalous pulmonary venous drainage. The patient underwent endocardial pacing explantation, balloon dilation and stenting of the right superior caval vein, banding of the levo-atrial cardinal vein to left upper pulmonary vein venous channel, and implantation of an epicardial pacing system. Discussion: Levo-atrial cardinal vein and partial anomalous pulmonary venous drainage with dual drainage can go undetected on cardiac imaging and may not ever cause symptoms (high left-to-right shunt or cyanosis). The levo-atrial cardinal vein and associated partial anomalous venous drainage with dual drainage was missed on multiple occasions and with multiple imaging modalities in our patient. Blood flow may not be detected in a small calibre or collapsed levo-atrial cardinal vein with pulmonary venous connection when the pulmonary vein remains widely patent and connected to the left atrium. Detailed comprehensive echocardiography of any child referred for cardiac intervention should include pulsed wave Doppler and colour flow mapping interrogation of the innominate vein from the suprasternal approach.