Figure 1.

Lateral (A) and posterior-anterior (dorsoventral) (B) thoracic radiographs obtained when SVT was identified (age 6.5 years), showing the typical appearance of a transvenous pacemaker in a dog. The lateral image is shown in standard veterinary orientation, with anterior (ventral) at the bottom of the image and superior (cranial) to the left. The lead enters the circulation through the right external jugular vein, the generator is placed in a subcutaneous pocket over the posterior neck (where it cannot be scratched at by a hind limb), and abundant redundancy is evident in the segment of the lead within the right atrium to reduce the risk of lead dislodgment from wide head excursions in a longer-necked species of patient. Evidence of marked left atrial enlargement is apparent on both projections.