title: A case of pacemaker implantation in the patient with duplication of the left innominate vein: a case report.
abstract: BACKGROUND
  Duplication of the left innominate vein is a rare systemic venous anomaly defined as the coexistence of a retroaortic innominate vein and a normally positioned left innominate vein. We describe a successful case of pacemaker implantation in a patient with duplication of the left innominate vein via a retroaortic innominate vein.
  
  
  METHODS
  A 70-year-old mentally challenged man was admitted to our hospital because of bradycardia and an altered state of consciousness. Electrocardiogram indicated sinus arrest and junctional escape rhythm with a heart rate of 40 beats/min; hence, a pacemaker was implanted. Left subclavian venography showed two vessels that were connected to the superior vena cava: a narrow, normal positioned left innominate vein and a tortuous vein. The normally positioned left innominate vein was too narrow to pass through with a guide wire. Therefore, we chose the tortuous vein for implantation. However, the procedure was difficult because of the vein's tortuosity. Finally, leads at the right atrium and ventricle were successfully implanted using a steerable stylet. After the procedure, computed tomography showed two innominate veins: a retroaortic innominate vein and narrow left innominate vein that was a duplication of the left innominate vein.
  
  
  RESULTS
  The exact embryogenesis of retroaortic innominate vein remains unknown and incidence of retroaortic innominate vein is very rare. But for cardiologists performing transvenous pacemaker insertion, the anomalous brachiocephalic vein may cause technical difficulty during a left arm approach.
  
  
  CONCLUSIONS
  In cases in which subclavian venography shows a tortuous vein, cardiologists should consider the presence of a retroaortic innominate vein.
authors.affiliation: Department of Cardiology, Tokyo Metropolitan Hiroo Hospital, 2-34-10, Ebisu, Shibuya-ku, Tokyo, 150-0013 Japan.
authors.forename: Iwanari
authors.initials: I
authors.lastname: Kawamura
authors.affiliation: Department of Cardiology, Tokyo Metropolitan Hiroo Hospital, 2-34-10, Ebisu, Shibuya-ku, Tokyo, 150-0013 Japan.
authors.forename: Rintaro
authors.initials: R
authors.lastname: Hojo
authors.affiliation: Department of Cardiology, Tokyo Metropolitan Hiroo Hospital, 2-34-10, Ebisu, Shibuya-ku, Tokyo, 150-0013 Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukamizu
keywords: Duplication of the left innominate vein; Pacemaker; Retroaortic innominate vein