The Cardiac Pacemaker Clinic: Memories From a Bygone Era.

In 1963, soon after the first ventricular pacemakers were implanted at the Royal Melbourne Hospital, attempts were made to identify impending pacing failure, thus preventing sudden death in these very vulnerable patients. By 1970, patient numbers had increased, a formal regular pacemaker clinic was established, and guidelines and protocols developed. The clinic was staffed by a physician, a biomedical engineer and cardiac technicians. The unipolar, asynchronous, non-programmable pulse generators were powered by mercuric oxide/zinc batteries and implanted in the abdomen, using either transvenous or epimyocardial leads. Although, pulse generators were electively replaced at 3 years, most had already been replaced because of power source depletion, electronic failure or lead issues. Testing in all patients involved an electrocardiographic rhythm strip and electronic analysis of the stimulus artefact using a calibrated high-speed storage oscilloscope. Results were compared to previous studies and significant changes were interpreted as impending power source depletion. As a result of this testing, 97% of cases of impending power source depletion were detected prior to failure. These findings allowed testing each 4 months and for pulse generator life to be extended beyond three years. With ventricular triggered pulse generators, new testing procedures were designed. With time, visiting regional centres and clinical evaluation of new products became important functions of the clinic.