Present state and future trends in electrical heart stimulation

Examples of electrical heart stimulation techniques are presented to illustrate for the physician and biomedical engineer the technical feasibility of realizing many therapeutic concepts by means of microelectronics. Because of the life-supporting applications, extremely high system reliabilty must be guaranteed. The usual methods of enhancing safety by providing redundancy cannot be used, and the service life requirements can be met only by appropriate adaptation of the current consumption due to the limited battery capacity. Based on the practical experience gained in the manufacture of more than 100,000 implantable devices, it can be reported that by rigid application of, and adherence to, quality assurance measures reliability values can be achieved of lambda = 10(-7)h-1 at a confidence level of 90% for the hybrid components and of lambda = 10(-9)h-1 for integrated circuits and passive components. The requirement for technical reliability of the implantable device for patient safety requires a thorough understanding of all technical and medical details of the therapeutic device. The success of future developments (e.g. the automatically-controlled systems which are meant to substitute for the multiprogrammable pacemakers) will not only require utilization of currently available technologies but also will depend to a great extent on active participation of the physicians in the development process itself.