Determination of local myocardial electrical activation for activation sequence mapping. A statistical approach.

Electrical activation sequence mapping requires accurate identification of local activation, but because extracellular recordings do not exclusively reflect local events, complex electrograms may be difficult to interpret. In such cases, the assignment of local activation is subject to error that could affect interpretation of the resulting activation maps. The purpose of this investigation was to develop an approach that would provide quantitative indexes of error in the determination of local activation. An electrode array with 64 closely spaced unipolar electrodes was used to record from the left ventricular surface during open heart surgery. Electrograms with multiple deflections were recorded from four patients with scarred myocardium; two other patients with normal myocardial function served as controls. Each of 784 deflections was scored on the basis of three features: evidence for propagation, the configuration of the bipolar signal, and the effect of changing from the chest to an average referenc...