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Improved frequency resolution for characterization of complex fractionated atrial electrograms

DOI: 10.1186/1475-925x-11-17

Keywords: Atrial fibrillation, Ensemble averaging, Fourier analysis, Spectral estimation, Spectral resolution

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Abstract:

In 10 paroxysmal and 10 persistent atrial fibrillation patients, 216 CFAE were acquired from the pulmonary vein ostia and left atrial free wall (977?Hz sampling rate, 8192 sample points, 8.4?s duration). With these parameter values, in the physiologic range of 3–10?Hz, two frequency components can theoretically be resolved at 0.24?Hz using Fourier analysis and at 0.10?Hz on average using the new technique. For testing, two closely-spaced periodic components were synthesized from two different CFAE recordings, and combined with two other CFAE recordings magnified 2×, that served as interference signals. The ability to resolve synthesized frequency components in the range 3–4?Hz, 4–5?Hz, …, 9–10?Hz was determined for 15 trials each (105 total).With the added interference, frequency resolution averaged 0.29?±?0.22?Hz for Fourier versus 0.16?±?0.10?Hz for the new method (p?<?0.001). The misalignment error of spectral peaks versus actual values was ±0.023?Hz for Fourier and ±0.009?Hz for the new method (p?<?0.001). One or both synthesized peaks were lost in the noise floor 13/105 times using Fourier versus 4/105 times using the new method.Within the physiologically relevant frequency range for characterization of CFAE, the new method has approximately twice the spectral resolution of Fourier analysis, there is less error in estimating frequencies, and peaks appear more readily above the noise floor. Theoretically, when interference is not present, to resolve frequency components separated by 0.10?Hz using Fourier analysis would require an 18.2?s sequence duration, versus 8.4?s with the new method.

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