A dual-sensor rate-responsive pacemaker algorithm incorporating a fuzzy logic expert system

The use of multiple sensors can potentially improve the performance of rate-responsive pacemakers. The design of algorithms to combine sensor inputs is complicated by the lack of explicit performance criteria. The design requirements often take the form of imprecise verbal statements by physicians, engineers, and marketing experts. A set of expert rules was developed to describe an algorithm combining activity and minute ventilation sensor inputs. The rules were reduced into a formal hierarchical rule base. The rule base was translated into a hierarchical fuzzy logic expert system. The antecedents and consequents of the rules were assigned monotonic membership functions. The resulting algorithm met the required end points and interpolated smoothly between them. The results of several tests of the algorithm showed that the rules derived from the stated requirements were not violated