PROBABILITY DENSITY-FUNCTION REVISITED - IMPROVED DISCRIMINATION OF VF USING A CYCLE LENGTH CORRECTED PDF

The probability density function (PDF) describes the fraction of time an electrogram signal spends at the baseline. In normal rhythm the sig nal is at baseline during the period between electrogram complexes, wh ile in fibrillation the signal exhibits continuous activity and spends little time at baseline. However, time spent at the baseline is depen dent on the rate of the rhythm, which limits the ability of the PDF al gorithm to discriminate ventricular fibrillation from fast nonfibrilla tory rhythms. A cycle length corrected version of the PDF algorithm ha s been formulated, which only examines the electrical activity between detected beats. The algorithm was developed utilizing a training set of 77 endocardial recordings and tested utilizing a test set of 90 end ocardial and 56 epicardial recordings. Ventricular fibrillation was de tected with 100% sensitivity and 98% specificity.