The 1st Pacemaker used clinically in a 10-year-old male Basenji dog was implanted in 1967 because the dog had recurrent congestive heart failure because of complete heart block. A fixed-rate (now called VOO) 70-beats per minute (bpm), bipolar pacemaker was placed in the left paralumbar fossa and 2 leads were passed subcutaneously and attached to the left ventricular epicardium through a separate thoracotomy.