Calculating endocardial potentials from epicardial potentials measured during external stimulation

A boundary integral method for calculating the potential field generated by external stimulation at locations within the heart using realistic heart geometry and samples of the potential taken from the epicardial surface is presented. This method assumes the heart is homogeneous and isotropic. To test the method epicardial and endocardial measurements are made in dogs during transthoracic pacing stimuli. From the epicardial potential measurements the endocardial potential values are predicted and compared with the measured data. Despite the seemingly gross assumptions, the mean correlation coefficient between the measured and predicted potentials for three dogs and eleven stimulation electrode configurations was 0.985, and the mean rms error was 17%.<
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