An InverseElectrocardiogra phic Solution with an ON-OFFModel

The electrical activity ofadog's heartismodeledas originating intenregions, called zones, eachofwhichiseither com- pletely active orcompletely inactive atanyonetime.Using this model, theelectrical activation sequence ofthedog's heartduring QRS iscomputed frompotentials measured onthedog's torso, and fromhisgeometry. Thesequence computed iscompared withmea- surements directly fromthedog's heart. Additionally, thesequence is recomputed withperturbations inthelocation oftheheart within the torsoandwithnoiseaddedtothetorsopotential datatoseehow greatly thesechanges affect thesolution. Theresults support the possibility ofusing anON-OFFmodeltodetermine theelectrical activity oftheheart.