Double superior vena cava and left brachiocephalic vein agenesis: a rare systemic vein anomaly and potential source of cardiac implantable electronic device and central venous catheter placement complications.

Abnormal systemic vein development produces anomalous veins, which - in the case of persistent left superior vena cava and/or left brachiocephalic vein - exhibit considerable topographic and morphometric differences in comparison with their usual anatomy. The nature and extent of those developmental anomalies - detected during intravenous procedures, such as cardiac implantable electronic device (CIED) lead insertion or central venous catheter placement - may hinder the procedure itself and/or adversely affect its outcome, both at the stage of cardiac lead advancement through an abnormally shaped vessel and lead positioning within the heart. This may lead to problems in achieving optimal sensing and pacing parameters and in ensuring that the patient cannot feel the pacing impulses. These events accompanied a de novo CIED implantation procedure in the patient with a double superior vena cava and left brachiocephalic vein agenesis, who ultimately required reoperation.