[Endocardial dual-chamber stimulation in an anomalous persistent left superior vena cava].

A persistent left superior vena cava was noted in a 63-year-old woman during pacemaker implantation because of sinus bradycardia and AV dissociation. During atrial test stimulation a 2 degree AV block occurred at a rate of only 110/min and dual-chamber provision was thus necessary. Both catheters were introduced into the right heart via the coronary sinus, but placement of the right-ventricular lead was made more difficult than usual because of looping. One year later pacemaker function (DDI mode) was unchanged and the patient symptom-free.