Estimation of cardiac conduction velocities using small data sets

Cardiac surface conduction velocities could provide valuable information about the speed and angle of a propagating electrical wave front. It would be advantageous to develop catheter-based velocity mapping devices to improve the visualization of cardiac arrhythmias. However, catheter tip size is limited to < or = 2.5 mm in diameter, restricting the number and size of electrodes that can be placed on a catheter tip. We address the feasibility of estimating conduction speed and angle from small data sets suitable for recording from a catheter device in a standard clinical environment. We estimated cardiac conduction velocities from data subsets of 4-7 closely spaced electrograms, and then compared these estimates to velocities estimated from a larger reference grid. We studied 137 ventricular beats and 17,756 velocity vectors from six swine hearts. Average differences in angle between the two estimates were 0.4 degrees +/- 16 degrees while average differences in speed were 5% +/- 33%. These angle and speed differences provide an initial quantitative assessment of velocity accuracy for the purposes of catheter-based vector mapping.