Sick sinus syndrome requiring permanent pacemaker implantation in a patient with mirror-image dextrocardia.

A patient with the sick sinus syndrome accompanying mirror-image dextrocardia which was associated with double superior venae cavae and an absent inferior vena cava is presented. A permanent transvenous demand pacemaker was inserted because of repeated episodes of dizziness and a documented 31/2-second period of asystole. Precise knowledge of the venous system and the location of the apex of the right ventricle was necessary prior to permanent pacemaker implantation.