Misplacement of temporary pacing wire into the left ventricle via an anomalous vein.

We report on a case where a temporary pacing wire that was inserted through the left internal jugular vein was subsequently noted to follow an unusual course on the chest radiograph. A 12-lead electrocardiogram showed right bundle branch block pattern during pacing, suggesting that the lead was pacing the left ventricle. Computed tomography of the chest demonstrated that the likely path of the pacing wire was through an anomalous vein that originated from the left subclavian vein and drained into the left atrium. The importance of paying careful attention to the chest radiograph and electrocardiogram after transvenous pacing are discussed.