Prediction of impending pacemaker failure in a pacemaker clinic

Abstract

A pacemaker clinic has been established for the detection of impending pacemaker failure. Over a two year period, there were 121 operations on 87 patients, comprising a third of our living patients. Of the 93 pacemaker replacements evaluated, 77 (83 percent) were for failure of the pulse-forming circuit and 16 (17 percent) for wire dislogment, heart perforation on lead fracture. Sixty-four percent of the pacemakers were replaced electively as a result of changes detected in the electrical impulses or the electrocardiogram. Only 10 percent of replacements were elective in patients not attending the clinic. On the basis of observed defects in the pacemakers, a maximal yield of 83 percent elective pacemaker replacements could have been anticipated from the test procedures of the clinic. The most significant changes observed were decreases in the artifact amplitude and in rate, especially if found together or in conjunction with alteration in pulse width or impulse configuration. Absolute indications were uncommon but included rounding of the square wave of Electrodyne units and loss of synchronization of any unit with a sensing circuit (standby and synchronous pacemakers). A computer simplified the clinic procedure by providing real-time rapid analysis of the data and a neat, concise report for the records. However, the computer was not necessary for preparing and evaluating the tests although it will be used for analog to digital conversion in further development of the clinic. The clinic provides close follow-up of all patients and gives them and their physicians the assurance that trouble will usually be spotted before it occurs. We believe that premature and emergency replacement of pacemakers can be avoided with this semiquantitative method.