Implantable stimulation device and method for discrimination atrial and ventricular arrhythmias

Abstract

By redistributing the running totals for various preliminary classifications to other preliminary classifications based upon the values of the most recent cardiac events, the present invention biases the running totals (thereby biasing the duration criteria) to help overcome common discrimination problems which permits the stimulation device to make a correct and final therapy decision more quickly. To identify a patient's heart rhythm, various electrical events such as P-waves and R-waves, and their timing, relationship, and stability, are detected and a preliminary classification is made for each detected event. Running totals of the numbers of all events detected within each of the preliminary classifications are maintained, along with sliding totals covering only the most recently detected events. Then, the arrhythmia is identified based upon an analysis of both the running totals and the sliding totals. In a preferred embodiment, the arrhythmia is identified by first determining whether the sliding total of the number of detected events in any one of the preliminary classifications exceeds a corresponding sliding total threshold. If so, the running totals are then selectively redistributed based upon the sliding totals. The final decision is then made based upon whether the running total corresponding to any one of the preliminary classifications exceeds a corresponding running total threshold. Both method and apparatus embodiments are disclosed. Methods are further described for determining the preliminary classifications of the detected events.