Permanent pacemaker implantation in a challenging anatomy: Persistent left superior vena cava.

The persistence of the left superior vena cava is one of the most common abnormalities that could affect the thoracic venous return, despite its rare occurrence. It can usually be found as the only or in combination with other congenital cardiac abnormalities. Even though it is usually asymptomatic and it rarely has important consequences on the hemodynamics, it could sometimes represent a serious threat. In this regard, PLSVC often represents an incidental finding during an invasive procedure or imaging. We present an interesting case of a 66-year-old patient, with permanent atrial fibrillation and chronic kidney disease who presented to our clinic for a syncope due to complete atrioventricular block. The implant procedure was marked by the incidental intraprocedural finding of unusual venous anatomy. This anomaly included the absence of the superior vena cava, with the communication of the right brachiocephalic trunk and right subclavian vein with a persistent left superior vena cava which drainage directly into the coronary sinus. The right-side approach, as well as the limitation of using contrast-based venography, due to the kidney disease, made the procedure more difficult, but the final position of an active fixation ventricular lead was successfully achieved with optimal and stable pacing parameters through the formation of a particular curve of the lead stylet. Persistence of the left superior vena cava is a venous anomaly, which is frequently suspicioned at transthoracic echocardiography examination when the examiner found a dilated coronary sinus but diagnosed on the implant table of a cardiac device. These anomalies can pose problems and exponentially increase the procedural time even in experienced hands.