Correspondence between the frequency domain characteristics of simultaneous surface and intra-atrial recordings of atrial fibrillation

Previous studies have shown a decrease in the median frequency of intra-atrial recordings of atrial fibrillation during the infusion of procainamide. This study determines if the changes in median frequency can be measured simultaneously in ECG leads. Remainder electrocardiograms were generated for lead II and VI before and after the administration of procainamide. The median frequency of the power spectrum of the remainder electrocardiograms as well as an intra-atrial lead were calculated. The average median frequency of the pre-procainamide segments ranged from 4.1-6.9 Hz for lead II; 4.1-6.9 Hz for lead VI; and 4.1-7.4 Hz for the intra-atrial lead. The average median frequency of the post-procainamide segments ranged from 4.2-5.8 Hz for lead II; 4.3-5.8 fit for lead VI; and 3.1-6.1 Hz for the intra-atrial lead. Considering each patient individually, correlation between the median frequency of the surface and intra-atrial leads ranged from 0.06 to 0.88