Left Superior Vena Cava Persistence in Patients Undergoing Pacemaker or Cardioverter-Defibrillator Implantation

The persistence of a left superior vena cava(LSVC) has been observed in 0.3% of the general population asestablished by autopsy. In the adult population, it is an importantanatomic finding if a left superior approach to the heart isconsidered. The aim of the study was to evaluate the prevalence of aLSVC in patients undergoing pacemaker (PM) andcardioverter-defibrillator (CD) implantation. We observed the prevalence of LSVC during a 10-year period; eachpatient undergoing PM or transvenous CD implantation received a leftcephalic/left subclavian venous approach to the heart. With thistechnique, LSVC persistence is easily diagnosed during leadplacement. A total of 1,139 patientsconsecutively underwent PM implantation during 10 years: 4 patients hadpersistent LSCV (0.34%). Among 115 patients undergoing CDimplantation, 2 patients with LSVC (1.7%) were observed. Overall LSVCpersistence was found in 6 of 1,254 patients (0.47%). Two patients, one of whom had no right superior vena cava (RSVC), received aleft-sided PM, whereas two other patients received right-sided devices. Both CD patients received a left-sided active-can device: the firstpatient with a right-sided lead tunneled to the left pectoral pocket, as a result of poor catheter handling through the LSVC and coronarysinus, and the second patient with a screw-in lead from LSVC. Long-termfollow-up of these patients (average ± SD, 41 ± 26 months)revealed absence of lead dislodgment and appropriate device functionregardless of lead implantation site. Persistence of LSVC in adults undergoing PM/CD implantation is similarto that of the general population (0.47% in our study). The left-sidedimplant can be achieved by stylet shaping and by use of active fixationleads in most patients, with a reliable outcome at short term inaddition to appropriate device performance at follow-up. Assessment ofthe RSVC is advisable when planning a right-sided implantation, since aminority of patients lacks this vessel.