Background: Physiologic pacing is increasingly used as an alternative when there is a failure in cardiac resynchronization therapy (CRT), with more challenging situations expected consequently.

Case Presentation: An 83-year-old Caucasian man underwent attempted CRT, but was found to have a persistent left superior vena cava (SVC) and absence of a right SVC. Additionally, no suitable coronary sinus (CS) veins were found. Instead, conduction system pacing with a modified approach was used.

Conclusions: The presence of left superior SVC is compatible with safe implantation of conduction system pacing, using conventional tools and with mild modification of typical technique.

Keywords: Conduction system pacing; Cardiac resynchronization therapy; Persistent left superior vena cava; Cardiology