A method for determining high-resolution activation time delays in unipolar cardiac mapping

A method is presented for determining activation time delays in unipolar cardiac mapping data to resolutions considerably smaller than the sample interval. The method involves taking two filtered, differentiated electrograms and computing the Hilbert transform of their cross correlation, which exhibits a negative-to-positive zero crossing at the delay time between the signals. We applied this method to estimate transmural activation time delays in the swine right atrium during sinus rhythm. We were able to calculate very precise time delay measurements, which exhibited much less variability than time delays calculated with more traditional methods. This method was also used to create an activation map of the swine right atrial epicardium during sinus rhythm, which was compared to an activation map calculated in the traditional manner