Pacemaker-twiddler's syndrome in a seven-year-old male domestic shorthaired cat

A seven-year-old male neutered domestic shorthaired cat underwent surgical placement of a permanent epicardial pacemaker following diagnosis of intermittent second and third degree atrioventricular block, which was responsible for 'seizure-like' episodes. Although the pacemaker implant was successful, the cat started experiencing near-syncopal episodes approximately one year after surgery. Ambulatory Holter recording showed periods of loss of capture. Therefore, the pacemaker was interrogated using incremental energy output, which did not evoke any capture, even at the highest possible pulse voltage and duration. Thoracic radiographs showed that the pulse generator had rotated compared to the original radiographic assessment and the lead appeared entangled and shortened, resembling the findings described as 'twiddler syndrome' in humans and dogs, which is characterised by twisting of the lead caused by rotation of the pulse generator around its long axis and subsequent lead migration. To the best of the authors' knowledge, this is the first report of twiddler syndrome in a cat.