Congestive heart failure caused by transvenous pacemaker lead prolapse and associated right ventricular outflow tract obstruction in a dog.

A 16-year-old dog was presented for cough as well as increased respiratory rate and effort three years after implantation of a single-lead transvenous artificial pacemaker system. Thoracic radiographs and echocardiography disclosed prolapse of the pacemaker lead into the main pulmonary artery, causing severe pulmonary insufficiency and right-sided volume overload. Repositioning of the pacemaker lead led to improvement of pulmonary insufficiency and resolution of the dog's clinical signs and cavitary effusions. This case describes a late complication of pacemaker implantation that may be avoided by appropriate use of the manufacturer-provided anchoring sleeve and avoidance of excessive lead redundancy.