Leadless Pacemaker Implantation in a Patient With Hypoplasia of the Left Brachiocephalic Vein.

Venous anomalies are typically asymptomatic and may be discovered unexpectedly at the time of implantation of a cardiac implantable electronic device. We report a case of leadless pacemaker implantation in a patient with hypoplasia of the left brachiocephalic vein who had previously undergone multiple interventions for relapsing right-sided breast cancer. The prevalence and etiology of this anatomic variant remain unknown. However, awareness of its existence may prevent complications during left-sided interventions. such as placement of a central venous line or a cardiac implantable electronic device. Alternative diagnostics and implantation strategies are discussed.