IC-ECG-guided port placement in three breast cancer patients with PLSVC showed no complications.

Persistent left superior vena cava (PLSVC) is a rare congenital venous anomaly. Although implantable venous access port placement in PLSVC has been reported, the optimal technique, catheter positioning, and safety considerations remain uncertain. This study describes our experience in managing three breast cancer patients with PLSVC and proposes a safe and efficient approach for port placement. All three cases of PLSVC were identified among breast cancer patients undergoing implantable venous access port placement guided by intracavitary electrocardiogram (IC-ECG). A negative P wave appeared on IC-ECG, and persisted as it advanced toward the predicted insertion length. These findings were reproducible on repeated catheterizations. To avoid excessive tip depth, the catheter was withdrawn by approximately 3 cm from the predetermined length. Postoperative X-ray and CT confirmed the final tip position at the T6 level. No functional impairment or catheter-related complications occurred during the entire course of treatment. Therefore, when placing a port from the left side, the presence of a negative P wave upon reaching the predetermined length may indicate PLSVC. Persistence of the negative P wave during further advancement, or the emergence of bidirectional P waves, should heighten suspicion for this anomaly. Postoperative X-ray and CT can confirm both the presence of PLSVC and the final tip position. Based on observed left-right predetermined length discrepancies in the normal population, withdrawing the catheter by approximately 3 cm from the predicted insertion length provides a useful reference. However, final confirmation of tip location should always rely on imaging.