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While bipolar electrograms have dominated electrophysiological studies of the atria in the past, unipolar electrograms come with advantages in undistorted morphology but pose undesirable interference with the ventricular far field (VFF). Blanking or template building are common approaches to alleviate this drawback but tremendously reduce data or prolong the procedure. None of the approaches is clinically satisfactory.
This study quantitatively evaluates the clinical performance of a VFF removal technique which builds a spatio-temporal model of the VFF in the atria to be applied to any location without prolonging the procedure.
The study comprised fourteen subjects with recordings both in sinus/paced rhythm and an atrial arrhythmia. The ventricular activation was modeled in space and time by electrical dipoles placed below the atria. Dipoles were parameterized to fit the VFF recorded in the atria with the Orion™ catheter during sinus/paced rhythm. The electrical potential emerging from the dipoles was propagated to the atria and subtracted from the unipolar electrograms. The residual VFF was quantified for datasets in sinus/paced rhythm and assessed for recordings during atrial flutter.
The median residual VFF amplitude amongst all patients was reduced from 1.64mV to 0.27mV. The median peak-to-peak amplitude of all unipolar atrial activations considered for mapping measured 2.71mV. More than 90% of the residual VFFs fell below the atrial activations of interest.
With the residual VFF dropping below the atrial signal of interest, the dipole method provides unipolar electrograms of high quality for clinical application.